Peter Sinclair has an amazing new video at Climate Denial Crock of the Week:
Click through to read the very informative post. (And more videos.)
Tag Archives: Global Warming
March 2015 Was A Very Warm Month
The last 12 months have been the warmest one year period in the NASA database since records began in 1880. According to the just released NASA GISS Global Temperature Data, March, 2015 is estimated to have been the fifth warmest month on record. Here are the top 20 months in rank order:
2007 JAN 93
2002 MAR 88
2010 MAR 87
1998 FEB 86
2015 MAR 84
2010 APR 82
2014 SEP 81
2015 FEB 78
2014 MAY 78
2014 OCT 77
2005 OCT 76
2015 JAN 75
2013 NOV 75
2010 NOV 75
1998 JUN 75
1995 FEB 75
2010 FEB 74
2006 DEC 74
2014 DEC 73
2014 AUG 73
Here is the monthly data covering the entire period of the instrumental record (1880 – present)
And, most importantly, here is the 12 month running mean (showing only since 1940 to make it easier to read):
And a couple more graphics showing the last few months up close:
And this is just looking at January through March for each year in the database:
With Global Warming, Will Cold Outbreaks Be Less Common?
Maybe, maybe not. There is a new paper that looks at what climate scientists call “synoptic midlatitude temperature variability” and the rest of us call “cold snaps” and “heat waves.” The term “synoptic” simply means over a reasonably large area like you might expect a cold snap or heat wave to be. Specifically, the paper (Physics of Changes in Synoptic Midlatitude Temperature Variability, by Tapio Schneider, Tobias Bischoff and Hanna Plotka, published in Journal of Climate) concludes that as human-caused greenhouse gas pollution increases, the frequency of cold snaps in the northern hemisphere will go down. Naturally, as temperatures warm up we would expect the highs to get higher, the averages to be higher, and the lows to be higher as well (and thus fewer cold spells). But the new research actually argues that the cold spells (the cold extremes at synoptic spacial scales) will become even less common. This is potentially controversial and conflicts with other recently published research.
The paper is rather technical so, I’ll give you the abstract so you can go take a class in climate science, then come back and read it:
This paper examines the physical processes controlling how synoptic midlatitude temperature variability near the surface changes with climate. Because synoptic temperature variability is primarily generated by advection, it can be related to mean potential temperature gradients and mixing lengths near the surface. Scaling arguments show that the reduction of meridional potential temperature gradients that accompanies polar amplification of global warming leads to a reduction of the synoptic temperature variance near the surface. This is confirmed in simulations of a wide range of climates with an idealized GCM. In comprehensive climate simulations (CMIP5), Arctic amplification of global warming similarly entails a large-scale reduction of the near-surface temperature variance in Northern Hemisphere midlatitudes, especially in winter. The probability density functions of synoptic near-surface temperature variations in midlatitudes are statistically indistinguishable from Gaussian, both in reanalysis data and in a range of climates simulated with idealized and comprehensive GCMs. This indicates that changes in mean values and variances suffice to account for changes even in extreme synoptic temperature variations. Taken together, the results indicate that Arctic amplification of global warming leads to even less frequent cold outbreaks in Northern Hemisphere winter than a shift toward a warmer mean climate implies by itself.
Why is this controversial? Because we have seen research in recent years indicating that with Arctic Amplification (the Arctic getting relatively warmer than the rest of the planet as global warming commences) the manner in which warm air is redistributed from sun-facing Equatorial regions towards the poles changes, which in turn changes the behavior of the Polar jet stream. Rather than being relatively straight as it rushes around the globe, separating temperate and sub-polar regions (and defining the boundaries of trade winds, and moving along storms) it is thought that the jet stream has become more often very curvy, forming what are called Rossby waves. These waves, recent research has suggested, can become stationary and the wind within the waves moves relatively slowly. A curvy jet stream forms meteorological features such as the “ridiculously resilient ridge” which has brought California nearly continuous dry conditions for at least two years now, resulting in an unprecedented drought. A curvy jet stream also forms meteorological features called “troughs” such as the excursion known last year (incorrectly) as the Polar Vortex, which also returned in less severe form this year; a bend in the jet stream that brings polar air farther south than usual, causing a synoptic cold spell of extensive duration. These changes in the jet stream also seem to have brought some unusual winter weather to the American Southeast last year, and have been implicated in steering Super Storm Sandy into the US Northeast a few years ago. And that flood in Boulder, and the flood in Calgary, and the June Of All Rain here in Minnesota last year, and so on. This is the main global warming caused change in weather systems responsible for what has been termed “Weather Whiplash” and may rank up there with increased sea surface temperatures as factors underlying the observable, day to day effects of human caused climate disruption.
I’ve talked about jet streams, Rossby waves, and such in a few places:
Even more recently was a paper by Dim Coumou, Jascha Lehmann, and Johanna Beckmann, “The weakening summer circulation in the Northern Hemisphere mid-latitudes” that argued:
Rapid warming in the Arctic could influence mid-latitude circulation by reducing the poleward temperature gradient. The largest changes are generally expected in autumn or winter but whether significant changes have occurred is debated. Here we report significant weakening of summer circulation detected in three key dynamical quantities: (i) the zonal-mean zonal wind, (ii) the eddy kinetic energy (EKE) and (iii) the amplitude of fast-moving Rossby waves. Weakening of the zonal wind is explained by a reduction in poleward temperature gradient. Changes in Rossby waves and EKE are consistent with regression analyses of climate model projections and changes over the seasonal cycle. Monthly heat extremes are associated with low EKE and thus the observed weakening might have contributed to more persistent heat waves in recent summers.
Coumou notes that “when the great air streams in the sky above us get disturbed by climate change, this can have severe effects on the ground. While you might expect reduced storm activity to be something good, it turns out that this reduction leads to a greater persistence of weather systems in the Northern hemisphere mid-latitudes. In summer, storms transport moist and cool air from the oceans to the continents bringing relief after periods of oppressive heat. Slack periods, in contrast, make warm weather conditions endure, resulting in the buildup of heat and drought.” Co-author Jascha Lehmann adds, “Unabated climate change will probably further weaken summer circulation patterns which could thus aggravate the risk of heat waves. Remarkably, climate simulations for the next decades, the CMIP5, show the same link that we found in observations. So the warm temperature extremes we’ve experienced in recent years might be just a beginning.”
These seem to be conflicting views.
So, how do the scientists who have published the recent paper that stands in stark contrast with these other recent findings explain the difference? I asked lead author Tapio Schneider to comment.
He told me that yes, there is a tension between the other work (the Comou et al paper) and his work, but there is also overlap and similarity. “Coumou et al. state that amplified warming of the Arctic should lead to reduced zonal jet speeds at fixed levels in the troposphere. This is an uncontroversial and well known consequence of thermal wind balance. Then they say that the reduced zonal jet speeds may lead to reductions in eddy kinetic energy (EKE), which is a measure of Rossby wave amplitude. That this can happen is likewise well documented. What affects eddy kinetic energies is a quantity known as the mean available potential energy (MAPE), which depends on temperature gradients (which also affect jet speeds) and other quantities, such as the vertical temperature stratification. Coumou et al. focus only on one factor influencing the EKE, the temperature gradient.”
The tension, he told me, is in what the other researchers (Coumou et al) draw from their results. “They show that warm summer months usually are associated with low EKE in the current climate, consistent with common knowledge: unusually warm conditions are associated with relatively stagnant air. They use this correlation in the current climate to suggest that reduced EKE in a future climate may also imply more (monthly) heat waves. While intuitive, this is not necessarily so. They say their suggestion is not in contradiction with our results because we considered temperature variability on shorter timescales (up to about two weeks), while their suggestion for more heat waves is made for monthly timescales. However, why the longer timescales should behave so differently is not made clear. “
As an onlooker, I take the following from this. First, there may be differences in time (and maybe space) scales of the analyses that might make them less comparable than ideal. Second, Schneider and Bischoff seem to be emphasizing synoptic cold outbreaks specifically. Schneider told me that they did look at temperature variability over longer time scales, but that did not make it into the paper. He said, “Even on monthly timescales, midlatitude temperature variance generally decreases as the climate warms, with a few regional exceptions (e.g., over Europe).”
Also, note that Schneider, Bischoff and Plotka, in this paper, do not address the specific problem of stationary Rossby waves, which probably has more to do with rainfall (lacking or heavy) than temperature, but is an important part of current changes in weather.
There has been some additional criticism of Schneider’s work on social media, etc. and perhaps the most significant one is this: Schneider, Bischoff and Plotka may have oversimplified the conditions in at least one of their models by leaving out continents. Also, Schneider et al has been picked up by a few of the usual suspects as saying that climate change will result in milder winters or less severe storms. This is not actually what the paper says. When people think “milder winter” they usually mean fewer severe storms, but various lines of evidence suggest that the notheastern US will experience more storms. For, example, see “Changes in U.S. East Coast Cyclone Dynamics with Climate Change” and “Global Warming Changing Weather in the US Northeast.”
UPDATE: I’ve received a comment from Dim Coumou pertaining to the differences between Schneider Et Al and Comou Et Al:
I see mostly overlap between the two studies, whereby ours really is an observational study analyzing data over the last 35 years (focusing on summers), and theirs is a theoretical and modeling study (focusing on winters). Interestingly both studies report similar dynamical changes but indeed come to somewhat different conclusions as to what this means for surface weather extremes.
We show that circulation (and notably EKE) has weakened in summer, that this has made weather more persistent and therefore favored the occurrence of prolonged heat waves in recent years. (We´re really focusing on present day climate and only show future projections for comparison with observations). As also discussed in our paper a drop in EKE leads to a reduction in weather variability on short timescales (less than a week) so this is consistent with the findings by Schneider et al. So indeed the issue of timescales is very important, and in my opinion prolonged extremes lasting several weeks are more important from an impact point of view.
Schneider, Bischoff and Plotka are well respected scientists and they are using methods that are generally accepted within climate science, yet have come to a conclusion different from what some of their colleagues have proposed. This is, in my opinion, a very good thing, and, certainly, interesting. I would worry if every climate scientist came up with the same result every time they tried something slightly different. The patterning (or changes in patterning) of air and sea currents under global warming has been the subject of a great deal of recent research, and there is strong evidence that changes are happening (such as in sea currents in the North Atlantic, and the jet stream effects discussed here) that have not been directly observed before. Because of the high level of internal (natural) variability, climate science works best when chunks of time 20 or 30 years long are considered. If we are seeing changes now that have really started to take off only five or ten years ago, and that are still dynamically reorganizing, how can the more ponderous, long term and large scale, thinking of climate science adjust and address those rapid changes? Well, we are seeing that process now in the climate change literature, and this paper is one example of it. I look forward to an honest, fair, and vigorous discussion in the peer reviewed literature.
Caption for the figure at the top of the post: FIG. 6. CMIP5 multimodel median values of 850-hPa potential temperature statistics for (left) DJF and (right) JJA. (a) Synoptic potential temperature variance u02 for the years 1980–99 of the historical simulations. (b) Per- centage change of the synoptic potential temperature variance u02 in the years 2080–99 of the RCP8.5 simulations relative to the years 1980–99 of the historical simulations shown in (a). (c) Percentage change of the squared meridional potential temperature gradient (›yu)2 in the years 2080–99 of the RCP8.5 simulations relative to the years 1980–99 of the historical simulations. (To calculate the gradients, mean potential temperatures were smoothed with a spherical harmonics filter that damped spherical wavenumbers greater than 6 and completely fil- tered out wavenumbers greater than 10.) (d) Percentage change of the squared mixing length L0 2 5 u0 2 /(›y u)2 implied by the variance and meridional potential temperature gradient, in the years 2080–99 of the RCP8.5 simulations relative to the years 1980–99 of the historical simulations. Synoptic potential temperature variations are bandpass filtered to 3–15 days. In the dark gray regions, topography extends above the mean 850-hPa isobar. The light gray bar blocks out the equatorial region, where potential temperature gradients are weak and their percentage changes become large.
How Sea Floor Ecosystems Are Damaged By, And Recover From, Abrupt Climate Change
A new study by Sarah Moffitt, Tessa Hill, Peter Roopnarine, and James Kennett (Response of seafloor ecosystems to abrubt global climate change) gets a handle on the effects of relatively rapid warming and associated Oxygen loss in the sea on invertebrate communities. The study looked at a recent warming event (the end of the last glacial) in order to understand the present warming event, which is the result of human-caused greenhouse gas pollution.
Here is what is unique about the study. A 30 foot deep core representing the time period from 3,400 to 16,100 year ago, was raised from a site in the pacific, and the researchers tried to identify and characterize all of the complex invertebrate remains in the core. That is not usually how it is done. Typically a limited number of species, and usually microscopic surface invertebrates (Foraminifera) only, are identified and counted. There are good reasons it is done that way. But the new study looks instead at non-single-celled invertebrates (i.e., clams and such) typically found at the bottom, not top, of the water column. This study identified over 5,400 fossils and trace fossils from Mollusca, Echinodermata, Arthropoda, and Annelida (clams, worms, etc.).
Complex invertebrates are important because of their high degree of connectivity in an ecosystem. In the sea, a clam, crab, or sea cucumber may be the canary in the proverbial coal mine. Study co-author Peter Roopnarine says, “The complexity and diversity of a community depends on how much energy is available. To truly understand the health of an ecosystem and the food webs within, we have to look at the simple and small as well as the complex. In this case, marine invertebrates give us a better understanding of the health of ecosystems as a whole.”
The most important finding of the study is this: the marine ecosystem sampled by this core underwent dramatic changes, including local extinctions, and took up to something like 1,000 years to recover from that. The amount of change in bottom ecosystems under these conditions was previously not well known, and the recovery rate was previously assumed to be much shorter, on the order of a century.
From the abstract of the paper:
Anthropogenic climate change is predicted to decrease oceanic oxygen (O2) concentrations, with potentially significant effects on marine ecosystems. Geologically recent episodes of abrupt climatic warming provide opportunities to assess the effects of changing oxygenation on marine communities. Thus far, this knowledge has been largely restricted to investigations using Foraminifera, with little being known about ecosystem-scale responses to abrupt, climate-forced deoxygenation. We here present high-resolution records based on the first comprehensive quantitative analysis, to our knowledge, of changes in marine metazoans … in response to the global warming associated with the last glacial to interglacial episode. The molluscan archive is dominated by extremophile taxa, including those containing endosymbiotic sulfur-oxidizing bacteria (Lucinoma aequizonatum) and those that graze on filamentous sulfur-oxidizing benthic bacterial mats (Alia permodesta). This record … demonstrates that seafloor invertebrate communities are subject to major turnover in response to relatively minor inferred changes in oxygenation (>1.5 to <0.5 mL·L?1 [O2]) associated with abrupt (<100 y) warming of the eastern Pacific. The biotic turnover and recovery events within the record expand known rates of marine biological recovery by an order of magnitude, from <100 to >1,000 y, and illustrate the crucial role of climate and oceanographic change in driving long-term successional changes in ocean ecosystems.
Lead author Sarah Moffitt, of the UC Davis Bodega Marine Laboratory and Coastal and Marine Sciences Institute notes, “In this study, we used the past to forecast the future. Tracing changes in marine biodiversity during historical episodes of warming and cooling tells us what might happen in years to come. We don’t want to hear that ecosystems need thousands of years to recover from disruption, but it’s critical that we understand the global need to combat modern climate impacts.”
There is a video:
Caption from the figure at the top of the post: Fig. 1. Core MV0811–15JC’s (SBB; 418 m water depth; 9.2 m core length; 34.37°N, 120.13°W) oxygen isotopic, foraminiferal, and metazoan deglacial record of the latest Quaternary. Timescale (ka) is in thousands of years before present, and major climatic events include the Last Glacial Maximum (LGM), the Bølling and Allerød (B/A), the Younger Dryas (YD), and the Holocene. (A) GISP2 ice core ?18O values (46). (B) Planktonic Foraminifera Globigerina bulloides ?18O values for core MV0811–15JC, which reflects both deglacial temperature changes in Eastern Pacific surface waters and changes in global ice volume. (C) Benthic foraminiferal density (individuals/cm3). (D) Relative frequency (%) of benthic Foraminifera with faunal oxygen-tolerance categories including oxic–mildly hypoxic (>1.5 mL·L?1 O2; N. labradorica, Quinqueloculina spp., Pyrgo spp.), intermediate hypoxia (1.5–0.5 mL·L?1 O2; Epistominella spp., Bolivina spp., Uvigerina spp.), and severe hypoxia (<0.5 mL·L?1 O2; N. stella, B. tumida) (19). (E) Log mollusc density (individuals/cm3). (F) Ophiuroids (brittle star) presence (presence = 1, absence = 0, 5-cm moving average). (G) Ostracod valve density (circles, valves/cm3) and 5-cm moving average.
Pine Beetle-Caused Forest Death, And Climate Change
There is some interesting new work carried out by researchers at Dartmouth College and the USDA Forest Service on the relationship between the Mountain Pine Beetle, major die-offs of forests in North America, and climate change.
The Mountain Pine Beetle (Dendroctonus ponderosae) is a kind of “bark beetle” (they don’t bark, they live in bark) native to western North America. They inhabit a very wide range of habitats and are found from British Columbia all the way south to Mexico. In British Columbia alone, the pine beetle, though a fairly complex process, has managed to destroy 16 of 55 million acres of forest. This epidemic of tree death is seen in mountain forest regions all across the western United States. The beetles affect a number of species of pine trees.
The beetle lays its eggs under the pine tree bark, and in so doing, introduces a fungus that penetrates adjoining wood. This fungus has the effect of suppressing the the tree’s response to the Pine Beetle’s larvae, which proceed to eat part of the tree. This suppressive effect blocks water and nutrient transport, together with the larvae eating part of the tree, quickly kills the host tree. The process can take just a few weeks. It takes longer for the tree to actually look dead (note the evergreen tree you cut and put in your living room for Christmas is dead the whole time it is looking nice and green and cheery). By the time the tree looks dead, i.e., the needles turn brown and fall off, it has been a dead-tree-standing for months and the Pine Beetles have moved on to find other victims.
It has long been thought that climate change has contributed to the western epidemic of Pine Beetles, as well as a similar epidemic in the Southeastern US (different species of beetles). The primary mechanism would be increasing winter extreme low temperatures. The very low temperatures would kill off the larvae, removing the threat of the beetle’s spread locally after that winter. Extreme winter temperatures have warmed by around 4 degrees C since 1960 across much of the beetle’s range. The lack of killing colds itself does not cause a beetle epidemic, but simply allows it, or produces a “demographic release.” If the beetles are already there, they have the opportunity to spread.
A recent study, just out, (see reference below) confirms this basic model but also adds a considerable degree of complexity. The study shows that there is not as strong of a correlation between raising winter temperatures above typical killing levels and the spread of the beetle. The study indicates that demographic release form an increase in extreme winter lows is part of the equation, but the situation is more complex and likely warming in general enhances beetle spread and reproduction during the summer part of its lifecycle, and may weaken the trees to make them more vulnerable to attack. In addition, other non-climate related factors probably play a role.
The study looked at several regions and assembled data on beetle frequency and spread over time, and various climate related data. From the abstract:
We used climate data to analyze the history of minimum air temperatures and reconstruct physio- logical effects of cold on D. ponderosae. We evaluated relations between winter temperatures and beetle abundance using aerial detection survey data… At the broadest scale, D. ponderosae population dynamics between 1997 and 2010 were unrelated to variation in minimum temperatures, but relations between cold and D. ponderosae dynamics varied among regions. In the 11 coldest ecoregions, lethal winter temperatures have become less frequent since the 1980s and beetle-caused tree mortality increased—consistent with the climatic release hypothesis. However, in the 12 warmer regions, recent epidemics cannot be attributed to warming winters because earlier winters were not cold enough to kill D. ponderosae…There has been pronounced warming of winter temperatures throughout the western US, and this has reduced previous constraints on D. ponderosae abundance in some regions. However, other considerations are necessary to understand the broad extent of recent D. ponderosae epidemics in the western US.
“This amount of warming could be the difference between pests surviving in areas that were historically unfavorable and could permit more severe and prolonged pest outbreaks in regions where historical outbreaks were halted by more frequent cold bouts,” says first author Aaron Weed, an ecologist at the National Park Service.
In the 11 coldest regions, winter temperatures cold enough to e lethal to D. ponderosae have become less frequent since the 1980s, and this is associated with an increase in tree mortality, confirming the link between warming conditions and increased parasite caused tree death. However, in the 12 regions with the warmest climate, recent epidemics are not clearly linked to warming winters simply because the earlier, colder, winters were already not cold enough to repress the tree-killing mountain pine beetle. This suggests that other factors may play a role in the epidemics in the western United States.
Evens so, the pattern of warming (including increase of minimum winter temperature) correlates to the demographic release of the mountain pine beetle. The authors note that “warming year-round temperatures that influence generation time and adult emergence synchrony … and drought effects that can weaken tree defenses …” are plausible explanations, but further note that a simple single explanation is not likely to be sufficient to explain the overall phenomenon. The link between warmer years, added number of generations per year, and the epidemic is explored here.
This is, in a sense, a numbers game. A cold winter does not kill off all of the beetles. However, no matter how cold the winter is, no beetles will be wiped out if they are not there to begin with. So, demographic release, which makes possible but does not cause an outbreak, could cause an abundance of beetles across a much larger area where, no matter what natural suppression may occur, they will then become more abundant over time.
As noted, the trees themselves matter. We can safely assume that generally changes in overall climate will mean that plant communities adapted to a given region might lose that adaptive edge and be subject to a number of problems which can then be exploited by a potentially spreading parasite. These changes in viability of plant communities are not all climate change related. Forest management, disturbance, and regional demographics (as forests age, they tend to change what they do) are also factors in this complex set of ecological relationships.
The bottom line. This study confirms the effects of warming, especially the increase of winter low temperatures, on the potential for D. ponderosae to spread rapidly locally and regionally. The study also calls into question the simplistic model that this is all that happens to explain the widespread epidemic of this beetle. Other factors, including other aspects of global warming, also contribute to the epidemics. In addition, and importantly, the study demonstrates a high degree of variability in the outcome of ecological and climate change.
This epidemic is probably the largest observed kill-off of forests caused by a parasite. So far it is much more severe in its effects than forest fires, but over the long to medium term, we will probably see increased frequency and severity of forest fires because of the abundance of fuel provided by the die-off.
Soucre:
Weed, A. S., Bentz, B. J., Ayres, M. P., & Holmes, T. P. (2015). Geographically variable response of Dendroctonus ponderosae to winter warming in the western United States. Landscape Ecology. doi:10.1007/s10980–015–0170-z
Text for the image at the top of the post, from the USDA:
The Mountain Pine Beetle is at epidemic levels throughout the western United States, including here in the Rocky Mountain Region … Forests affected here include several in Colorado, Wyoming, South Dakota and Nebraska. In northern Colorado and southeastern Wyoming, Mountain Pine Beetles have impacted more than 4 million acres since the first signs of outbreak in 1996. The majority of outbreaks have occurred in three forests: Arapaho-Roosevelt, White River and Medicine Bow/Routt.
Boston Snow Storms and Climate Change
From the Yale Climate Connections, a brief interview with Michael Mann.
Global warming can cause record winter storms. It may sound counterintuitive, but it’s no snow job. When the oceans warm, more water evaporates into the air.
MANN: “And what that means is there’s more precipitation. Water is cycling more vigorously through the atmosphere, and that gives us more extreme weather.”
That’s Michael Mann, a professor of meteorology at Penn State University. He says in summer, an unusually warm ocean can strengthen storms like Hurricane Irene.. but in winter, the evaporation from a warm ocean collides with cold arctic air and turns to snow.
As seawater evaporates, it also releases additional energy into the atmosphere. This extra energy then fuels storms, making them more intense.
This past winter, a large area of the North Atlantic was much warmer than usual — which Mann says contributed to the record Nor’easters that buried parts of New England in snow.MANN: “So climate change is actually providing more energy to intensify these nor’easters, and it’s providing more moisture so that they can convert that moisture into record snowfalls.”
2014 was the warmest year on record for the global ocean surface. So New England, get your shovels ready for more extreme snow in coming years.
Antarctic Ice Shelves Melting at Accelerating Rate
Antarctica is pretty much covered with glaciers. Glaciers are dynamic entities that, unless they are in full melt, tend to grow near their thickest parts (that’s why those are the thickest parts) and mush outwards towards the edges, where the liminal areas either melt (usually seasonally) in situ or drop off into the sea.
Antarctic’s glaciers are surrounded by a number of floating ice shelves. The ice shelves are really the distal reaches of the moving glaciers floating over the ocean. This is one of the places, probably the place at present, where melting accelerated by human caused greenhouse gas pollution occurs. The ice shelves are fixed in place along their margins (they typically cover linear fjord like valleys) and at a grounding point underneath the shelf some distance form the ice margin but under sea level.
The collapse or disintegration of an ice shelf is thought to lead to the more rapid movement of the corresponding glacial mass towards the sea, and increased melting. This is the big problem right now with estimating the rate of glacial melting in the Antarctic. This is not a steady and regular process, as rapid disintegration of an ice shelf is possible. Most likely, Antarctic glacial melting over the coming decades will involve occasional catastrophic of an ice shelf followed by more rapid glacial melting at that point.
Unfortunately, the ice shelves are generally becoming more vulnerable to this sort of process, a new study just out in Science shows. From the abstract:
The floating ice shelves surrounding the Antarctic Ice Sheet restrain the grounded ice-sheet flow. Thinning of an ice shelf reduces this effect, leading to an increase in ice discharge to the ocean. Using eighteen years of continuous satellite radar altimeter observations we have computed decadal-scale changes in ice-shelf thickness around the Antarctic continent. Overall, average ice-shelf volume change accelerated from negligible loss at 25 ± 64 km3 per year for 1994-2003 to rapid loss of 310 ± 74 km3 per year for 2003-2012. West Antarctic losses increased by 70% in the last decade, and earlier volume gain by East Antarctic ice shelves ceased. In the Amundsen and Bellingshausen regions, some ice shelves have lost up to 18% of their thickness in less than two decades.
This is one of many reasons that even the most extreme of the IPCC estimates of ice loss (generally) and its contribution to sea level rise have to be seen as a lower limit. This is a substantial change, and it is very recent. It isn’t just that the ice sheets have gotten thinner, but also, that the rate of melting at these margins is increasing.
Caption to figure: Fig. 1 Eighteen years of change in thickness and volume of Antarctic ice shelves.
Rates of thickness change (m/decade) are color-coded from -25 (thinning) to +10 (thickening). Circles represent percentage of thickness lost (red) or gained (blue) in 18 years. Only significant values at the 95% confidence level are plotted (see Table S1). Lower left corner shows time series and polynomial fit of average volume change (km3) from 1994 to 2012 for the West (in red) and East (in blue) Antarctic ice shelves. Black curve is polynomial fit for All Antarctic ice shelves. We divided Antarctica into eight regions (Fig. 3), which are labeled and delimited by line segments in black. Ice-shelf perimeters are shown as a thin black line. The central circle demarcates the area not surveyed by the satellites (south of 81.5°S). Original data were interpolated for mapping purposes (see Table S1 for percentage area surveyed of each ice shelf). Background is the Landsat Image Mosaic of Antarctica (LIMA).
Drought in California and Climate Change: They are linked
A paper just out now in PNAS by Noah Diffenbaugh, Daniel Swain, and Danielle Touma shows that “Anthropogenic warming has increased drought risk in California.” From the abstract:
… We find that although there has not been a substantial change in the probability of either negative or moderately negative precipitation anomalies in recent decades, the occurrence of drought years has been greater in the past two decades than in the preceding century. In addition, the probability that precipitation deficits co-occur with warm conditions and the probability that precipitation deficits produce drought have both increased. Climate model experiments with and without anthropogenic forcings reveal that human activities have increased the probability that dry precipitation years are also warm. Further, a large ensemble of climate model realizations reveals that additional global warming over the next few decades is very likely to create ?100% probability that any annual-scale dry period is also extremely warm. We therefore conclude that anthropogenic warming is increasing the probability of co-occurring warm–dry conditions like those that have created the acute human and ecosystem impacts associated with the “exceptional” 2012–2014 drought in California.
Michael Mann and Peter Gleick have written a commentary for PNAS to accompany that research. The graphic at the top of the post is from that study. They note:
California is experiencing extreme drought. Measured both by precipitation and by run- off in the Sacramento and San Joaquin river basins, 10 of the past 14 y have been below normal, and the past 3 y have been the driest and hottest in the full instrumental record. A plot of temperature and precipitation anom- alies over the full instrumental record from 1895 through November 2014 shows that the 3-y period ending in 2014 was by far the hottest and driest on record (Fig. 1). As of the publication of this commentary, the state appears headed into a fourth consec- utive year of water shortfall, leading to massive groundwater overdraft, cutbacks to farmers, reductions in hydroelectricity gen- eration, and a range of voluntary and man- datory urban water restrictions.
A number of studies have examined the California drought to try to determine if it was “caused by” (or otherwise affected by) human greenhouse gas pollution. These studies vary in their level of attribution, but increasingly it is becoming clear that anthropogenic global warming has a very big hand in this.
Mann and Gleick tackle the problem of defining drought. There are multiple ways to do so, and they relate to different causes. The plethora of definitions and relevant variables allows for a given study to miss any global warming effect by picking certain factors and ignoring others. Studies that look mainly at inputs to the hydrological system (i.e., rainfall) tend to miss the output part of the equation, including evaporation, which is exacerbated by a warming climate. Mann and Gleick point out that the Diffenbaugh study adds significant weight to the idea that anthropogenic climate change has increased the frequency, magnitude, and duration of California’s droughts. Perhaps more importantly, the Diffenbaugh study suggests “the emergence of a climatic regime in which all future dry years coincide with warmer conditions.”
Gleick told me, “The scientific evidence showing the growing influence of climate changes on extreme events around the world, including the ongoing California drought, continues to pile up. The clearest piece of this is the record high, and increasing, temperatures, which directly influence the availability and demand for water, but there is also growing evidence that climate change is influencing pressure dynamics and atmospheric circulation patterns that either bring, or divert, water from the west coast of the United States.”
So, the current drought in California is linked to human induced climate change, and in the future, this will be a more common phenomenon than it has in the base, according to the best available science. But what about other effects of climate change? I asked Michael Mann about the relationship between California Drought and his recent study showing that we should soon be entering a period (over the next couple of decades) during which heat that has been hiding in the oceans will be leaving it’s watery milieu and joining us up here on the surface. He told me, “Here is the linkage I think is most relevant: the “faux pause”, in our recent study, was closely tied to the predominance of La Nina-like conditions in the tropical Pacific for a large part of the past decade, and these same conditions are closely linked with California drought (La Nina years tend to be drought years in California, while El Nino years tend to be wet years—though this doesn’t necessarily hold true for every single event). So one might imagine that a return to a greater tendency for El Nino-like conditions in the tropical Pacific over the next decade or two (which would spell an end to the “Faux Pause”) could actually be a mitigating effect as far as California drought is concerned. A bit counter-intuitive, but that’s best assessment here.”
New Research Shows Exceptional Slowdown In Major Atlantic Ocean Currents (UPDATED)
Climate scientists have noticed a disturbing pattern in the North Atlantic. This is the relative cooling of surface waters in the area fed by the Gulf Stream. This pattern has emerged over recent decades, and may portend very rapid and potentially disruptive climate change in the upcoming decades. The cooling is not subtle at all, and looks like this:
So what does this mean? A paper out just today describes, explains, and discusses this odd anomaly and its potential consequences. First, a bit of context.
The Earth’s climate follows certain patterns. Most obviously it is warmer at the equator, colder at the poles. Less obvious if you’ve not looked into this is the presence of a very wet band around the middle of the earth, flanked to the north and south by irregular dry bands (that’s where most of the deserts are), with these flanked by the temperate zone, where you have more moisture and highly seasonal temperatures, and so on.
This pattern emerges as a complex response to two major inputs. First the Earth is spinning, and second, the Earth is heated more at the equator than the poles, so heat must move through air and water currents towards the north and south.
One of the major systems that moves heat away from the equator is known sometimes as the Atlantic Conveyor, which is really part of a lager system of sea currents that includes the Gulf Stream. Notice that the Indian Ocean is sequestered mostly in the Southern Hemisphere, bordered along the west by Africa and the north by Asia. Extra warm water in the Indian ocean tends to make its way around the southern tip of Africa, and up the Atlantic, which is a round about route. This water eventually makes its way to the North Atlantic, where it cools, and owing to evaporation, becomes extra salty. This drives the formerly warm surface water into the depth of the ocean, where it flows along the bottom of the Atlantic south, eventually returning (I oversimplify a bit) to the Indian Ocean and elsewhere.
This system is also known as the AMOC (Atlantic Meridional Overturning Circulation) and is part of the global “Thermohaline Circulation” system.
Meanwhile, a smaller but similar aspect of this system starts with the Gulf of Mexico. This water becomes quite warm from the Sun, but is blocked from moving directly north by the presence of North America, with Florida adding to the captive nature of those waters. But the water does make its way around Florida and flows north along the East coast of the US, and eventually also reaches the North Atlantic, and similarly, contributes to the saline deep currents.
Because salinity partly, even largely, drives this system, adding fresh water to the North Atlantic may interfere with this system of currents. How do you get enough fresh water to do this? In the past, huge volumes of fresh water probably entered the North Atlantic every now and then as large outflows of giant inland lakes, formed by melting glaciers, broke through barriers of ice or sediment. There is some evidence that in the past this sort of thing may have partly, or even completely, shut down the Atlantic Conveyor system, which would have had huge impacts on climate.
Today there seems to be two main sources of extra fresh water in the area. One is during years (or decades) when there is a larger than usual number of ice bergs floating into the North Atlantic from the Arctic. The other, potentially, is from melting of Greenland’s fast glaciers, a process that has recently speeded up because of human caused greenhouse gas pollution warming the Earth.
By now you may recognize this scenario as the basis for the Hollywood disaster movie “The Day After Tomorrow.” In that movie the thermohaline circulation system shut down and an ice age instantly gripped the planet. Giant frozen tornadoes came plummeting down from the Stratosphere. One of them hit the helicopter the British Royal Family was escaping in. Everybody in the US ended up in Mexico.
Every one who survived, that is.
The thing is, now, this can’t happen. Well, that particular scenario can’t ever really happen. But yes, the shutting down of this system can theoretically cause the onset of an ice age, or at least a mini-ice age, and has done so in the past. But no, it can’t now because our planet has warmed too much from human greenhouse gas pollution to allow that to happen. That may be the one good thing about global warming.
The new research does suggest, though, that this major pattern of circulation appears to be slowing down. This will have a number of effects. It will likely change the weather in Europe a bit. It will likely cause an increase in sea level along the US East Coast, because the current (and former) system piles up water towards the east and lowers it in the west, within the North Atlantic. That could be worth a few inches.
According to lead author Stefan Rahmstorf, “It is conspicuous that one specific area in the North Atlantic has been cooling in the past hundred years while the rest of the world heats up. Now we have detected strong evidence that the global conveyor has indeed been weakening in the past hundred years, particularly since 1970,” says Rahmstorf. If the slowdown of the Atlantic overturning continues, the impacts might be substantial. Disturbing the circulation will likely have a negative effect on the ocean ecosystem, and thereby fisheries and the associated livelihoods of many people in coastal areas. A slowdown also adds to the regional sea-level rise affecting cities like New York and Boston. Finally, temperature changes in that region can also influence weather systems on both sides of the Atlantic, in North America as well as Europe.”
The researchers used a combination of sea surface, atmospheric, and proxy (mainly coral) indicators of temperature to indirectly measure changes in ocean currents over time.
According to climate scientist Jason Box, “Now freshwater coming off the melting Greenland ice sheet is likely disturbing the circulation. So the human-caused mass loss of the Greenland ice sheet appears to be slowing down the Atlantic overturning – and this effect might increase if temperatures are allowed to rise further.” Michael Mann, another author of the paper, adds, “Common climate models are underestimating the change we’re facing, either because the Atlantic overturning is too stable in the models or because they don’t properly account for Greenland ice sheet melt, or both. That is another example where observations suggest that climate model predictions are in some respects still overly conservative when it comes to the pace at which certain aspects of climate change are proceeding.”
What happens if the system actually turns off completely? It was formerly thought that the chances of this happening were small, but this research, conforming to a growing body of expert opinion, suggest that the chances of that may be higher than previously thought. Were this to happen the main characteristic of any effects would be rapidity. Whatever happens would happen fast, and rapidly changing climate is generally regarded as bad no matter what the change itself really is.
UPDATE ADDED:
A criticism of this work has emerged, suggesting that another study indicates that there is no a long-term slowdown of the Atlantic Meridional Overturning Circulation (as suggested by the research covered here). That criticism is incorrect. Michael Mann, one of the AMOC study’s author has written a clarification on his facebook page. He begins:
Some critics have tried to make hay over a previous article from last year by URI Graduate School of Oceanography scientist Tom Rossby (see: http://www.gso.uri.edu/b…/rossby-gulf-stream-is-not-slowing/) they claim contradicts our recent Nature Climate Change study finding evidence for a long-term slowdown of the Atlantic Meridional Overturning Circulation (“AMOC”). …
Rossby employs direct measurement of Gulf Stream transport using a ship-board acoustic Doppler current profiler (ADCP) over the interval 1993-2012. I have no reason at all to doubt Rossby’s findings. And they do *not* conflict with our own findings (though some have misleadingly sought to assert they do) for two fundamental reasons:
Mann’s entire post is HERE and you should go read it.
Additional Resources:
The article:
Rahmstorf, S., Box, J., Feulner, G., Mann, M., Robinson, A., Rutherford, S., Schaffernicht, E. (2015): Evidence for an exceptional 20th-Century slowdown in Atlantic Ocean overturning. Nature Climate Change (online) [DOI: 10.1038/nclimate2554 ]
Stefan Rahmstorf, lead author, has this blog post at RealClimate: What’s going on in the North Atlantic?
Figure caption from the original article, goes with the graphic at the top of the post:
Figure 3. Surface temperature time series for different regions. Data from the proxy reconstructions of Mann et al.12,13, including estimated 2-? uncertainty bands, and from the HadCRUT4 instrumental data49. The latter are shown in darker colours and from 1922 onwards, as from this time on data from more than half of all subpolar-gyre grid cells exist in every month (except for a few months during World War II). The orange/red curves are averaged over the subpolar gyre, as indicated on Fig. 1. The grey/black curves are averaged over the Northern Hemisphere, offset by 3 K to avoid overlap. The blue curves in the bottom panel show our AMOC index, namely the difference between subpolar gyre and Northern Hemisphere temperature anomalies (that is, orange/red curves minus grey/black curves). Proxy and instrumental data are decadally smoothed.
A neat video of the thermohaline circulation system.
A movie produced by Peter Sinclair, that goes along with THIS blog post.
Coverage by Chris Mooney at the Washington Post: Global warming is now slowing down the circulation of the oceans — with potentially dire consequences
Other posts of interest:
– [Important new meta-study of sea level rise in the US.](http://scienceblogs.com/gregladen/2014/09/05/important-new-meta-study-of-sea-level-rise-in-the-us/)
– [Whatever you thought about sea level rise, it’s worse than you were thinking.](http://scienceblogs.com/gregladen/2013/12/05/whatever-you-thought-about-sea-level-rise-its-worse-than-you-were-thinking/)
– [How high can the sea level rise if all the glacial ice melted?](http://scienceblogs.com/gregladen/2013/06/18/how-high-can-the-sea-level-rise-if-all-the-glacial-ice-melted/)
– [Bangladesh and Sea Level Rise](http://scienceblogs.com/gregladen/2013/04/29/bangladesh-and-sea-level-rise/)
Also of interest: In Search of Sungudogo: A novel of adventure and mystery, set in the Congo.
Shut. Up. NOAA says February 2nd Warmest on Record
And by “Shut. Up.” I mean shut up about whether or not global warming is real.
The National Climatic Data Center of NOAA has just released the number representing the Earth’s surface temperature for February and it is a shocking 0.82 degrees C above the 20th century average. This is the second warmest Feb on record, and I’m pretty sure it is the third warmest month on record, in that data base.
Roughly speaking, the coldest we have experienced, the Last Glacial Maximum, was about 6 degrees colder than at present. It is generally thought that we need to keep the global surface temperature below about 2 degrees C above the preindustrial level. The 20th century average used by NOAA includes decades warmed considerably by human caused greenhouse gas pollution; the actual difference between the best estimate (BEST 1750-1850) of the pre-industrial temperature and the present is about 1.5 degrees C.
This high value is not surprising since the estimate of the Earth’s surface temperature from NASA GISS, which came out a few days ago, also places February very high in temerature.
March, by the way, has been pretty warm. We’ve had quite a trend of very warm months, and it appears to not be letting up.
For a comparative perspective, see also this.
President Obama Talks About Climate Change
The President speaks about making progress on climate change. And other things. Really good interview.
February Was Very Warm, Continues Upward Global Warming Trend
The NASA GISS data for surface temperatures of the planet Earth are in for February, and February was warm. The anomaly value was 79, which means 0.79 degrees C above a the baseline NASA uses (1951-1980). So, while it looks like the planet has warmed by a about 8 tenths of a degree, since warming started well before 1880, it is really more like a whole degree or more. Depending on what you know and don’t know about how climate works, that may seem like a lot or a little. Trust me, it is a lot.
Most interestingly, the last 12 months were the warmest 12 months in the NSAS GISS database (you’ll remember that 2014 was the warmest year in that database as well as other). This continues an upward trend of temperatures that we expect with global warming.
February 2015 was the seventh warmest month in the entire GISS record, which goes back to 1880. All of the warmest months have been recent. February 2015 was the second warmest February in that record.
We are not going to know about March officially for another month (obviously!), but indications are that March has been warm and will continue to be warm, so I don’t see this trend turning around.
If you want a higher resolution version of this graphic, click here, then click through to the original file.
Here is a version of the above graph without the trendline:
Again, go HERE to get a higher resolution version (Scienceblogs is very efficient at scaling down graphics!).
New Study On How Global Warming Changes The Weather
Human caused greenhouse gas pollution has warmed the planet. Global warming means more extreme weather. Many meteorologist who watch the weather every day see this. More and more research shows that greenhouse gas pollution changes the weather in a way that causes even more change in the weather. Changing weather systems means more lightning, increased high precipitation events in certain regions like the US Northeast, including more frequent large snow storms.
Global warming has had uneven effects. The Arctic has warmed relatively more than most of the rest of the planet. The major movements of air masses are driven by a combination of the rotation of the Earth and the movement of extra heat from the Equator towards the poles, a process that sets up the trade winds and the jet stream. But the additional warming in the Arctic has changed this pattern measurably, resulting in these and other changes in weather patterns.
A new study out in Science, by Dim Coumou, Jascha Lehmann, and Johanna Beckmann, “The weakening summer circulation in the Northern Hemisphere mid-latitudes,” demonstrates that storm activity in much of the Northern Hemisphere has changed in a way that matters to our weather, and is likely to change more in the future. From the abstract:
Rapid warming in the Arctic could influence mid-latitude circulation by reducing the poleward temperature gradient. The largest changes are generally expected in autumn or winter but whether significant changes have occurred is debated. Here we report significant weakening of summer circulation detected in three key dynamical quantities: (1) the zonal-mean zonal wind, (2) the eddy kinetic energy (EKE) and (3) the amplitude of fast-moving Rossby waves. Weakening of the zonal wind is explained by a reduction in poleward temperature gradient. Changes in Rossby waves and EKE are consistent with regression analyses of climate model projections and changes over the seasonal cycle. Monthly heat extremes are associated with low EKE and thus the observed weakening might have contributed to more persistent heat waves in recent summers.
The study has been written up by Chris Mooney, in the Washington Post, and Roz Pidcock at Carbon Brief. From the study’s press release,
“When the great air streams in the sky above us get disturbed by climate change, this can have severe effects on the ground,” says lead-author Dim Coumou. “While you might expect reduced storm activity to be something good, it turns out that this reduction leads to a greater persistence of weather systems in the Northern hemisphere mid-latitudes. In summer, storms transport moist and cool air from the oceans to the continents bringing relief after periods of oppressive heat. Slack periods, in contrast, make warm weather conditions endure, resulting in the buildup of heat and drought.”
“Unabated climate change will probably further weaken summer circulation patterns which could thus aggravate the risk of heat waves,” says co-author Jascha Lehmann “Climate simulations for the next decades, the CMIP5, remarkably show the same link that we found in observations. So the warm temperature extremes we’ve experienced in recent years might be only a beginning.”
Bjorn Lomborg Is Wrong About Bangladesh And Sea Level Rise
Human caused greenhouse gas pollution is heating the Earth and causing the planet’s polar ice caps and other glacial ice to melt. This, along with simply heating the ocean, has caused measurable sea level rise. Even more worrisome is this: the current elevated level of CO2 in the atmosphere was associated in the past with sea levels several meters higher than they are today. Even if we slow down Carbon pollution very quickly, we can expect sea levels to be at least 8 meters higher, eventually. How soon? Nobody knows, nobody can give you a time frame on this because the rate of melting of the major glaciers in Greenland and the Antarctic is hard to measure. All we know for sure is that the rate of melting is speeding up, and that in the past, the current level of atmospheric CO2 has typically caused a very large amount of melting.
Bangladesh is low country. A very large percentage of the country is on the Bangladesh Plain, which is almost entirely below 10 meters in elevation. This is where a large portion of the population in that country lives, and where a large portion of the food is grown. The greenhouse gas pollution we have caused so far is sufficient to virtually guarantee that Bangladesh will become a very small country over the next generation or two. Much sooner than that, though, sea level rise in the region will affect, and is already affecting, freshwater reserves. We expect the largest tropical storms to become larger and more intense as an effect of human caused global warming. Sea level rise makes the storm surges from those events worse. So of immediate concern and becoming more of a problem every year is the threat of deadly and damaging tropical storms exacerbated by warming of the seas and increased sea levels.
The deadliest tropical cyclone on record occurred in Bangladesh; that was the Great Bhola Cyclone of 1970, which killed up to one half of a million people. The second deadliest cyclone known hit Bangladesh and India in great antiquity. Eight of the ten deadliest known tropical cyclones hit the region. So, tropical cyclones are already a problem in Bangladesh, and sea level rise and increased cyclone strength are going to make that much much worse.
Bjørn Lomborg, in a recent interview, told Bangladesh, the country, not to worry too much about global warming, and instead, to focus on other problems. He equated concern over sea level rise in a country where sea level rise is a very significant problem with immorality. While Lomborg may be correct to point out the obvious – that Bangladesh has a lot of problems in public health and other areas to worry about – he is wrong to suggest that sea level rise in that low lying country can be addressed just as the Dutch have managed the sea in The Netherlands.
Lomborg seems to not know much about sea level rise. He once noted that sea level rise had stopped, or even decreased, by referring to a single year’s worth of data (see graphic above). That statement and his suggestion that sea level rise should be a low priority in a country that may be the most threatened by sea level rise in the world (aside from island nations) is reminiscent of a statement by J.R. Spradley, a delegate at an international conference on climate change in 1990, speaking about sea level rise in Bangladesh. He was quoted in the Washington Post as saying “The situation is not a disaster; it is merely a change. The area won’t have disappeared; it will just be underwater. Where you now have cows, you will have fish.” (Washington Post, December 30th, 1990.)
Part of Lomborg’s argument is typical for him. He generates a straw man by equating concern over climate change with concern over a meteor about to smash into the earth. In the interview he said,
Projecting scary scenarios are probably unhealthy to deal with real issues. Now, if there was a meteor hurtling towards earth, we should tell people. If there was really something destroying the earth we should definitely be telling people and doing something about it. My point is if you, for instance, look at climate change, it is often portrayed as the end of the world. But if you look at for instance the UN climate panel, they tell us by about 2070 the total cost of global warming is going to be somewhere between 0.2 and 2% of the GDP. And that emphasises what I am trying to say – global warming is real, it is a problem, it is something we should fix, but it’s not the end of the world.
The problem with this is that sea level rise is, essentially, the end of the world, if you are Bangladesh.
The most troubling part of Lomborg’s statements is that he equates the Netherlands with Bangladesh. The Netherlands is about 25% below sea level, but the sea is kept back by dikes. Other than their cheese, chocolate, love of splitting the restaurant tab, this is probably what the Dutch are most known for. Indeed Dutch engineers were drafted into managing water related problems around the world for centuries. So maybe the Dutch can help Bangladesh keep the Indian Ocean off it’s turf when that ocean is 8 meters above the present level. Lomborg looks to the Dutch to do just this:
… how much of a problem is [sea level rise in Bangladesh]? The Dutch has shown us 200 years ago, you can handle sea level rise fairly, easily and cheaply, you can do the same thing here and you will do the same thing here. Remember when people say, global warming is a big problem and we need to put a wind turbine here – any amount of wind turbine or solar panels that we are going to put in the next 50 years, are going to have absolutely no impact on the sea level rise that towards the end of the century. They may make a tiny difference towards the 22nd century, but if want to do anything about sea level rise, it’s all about adaptation. Globally there seems to be actually less ferocious hurricanes, one measure is accumulated cyclone energy, which is sort of a good global estimate and it’s actually been at some of the lowest levels since we started monitoring in the 1970s. There is a theoretical argument that you will see slightly fewer but slightly stronger hurricanes towards the end of the century. Again, this is not by any means the end of Bangladesh.”
The Netherlands is about 41,543 square kilometers in size with about 17% of that reclaimed from the sea, this and other land kept dry by dikes. Bangladesh is about 147,570 square kilometers. The Netherlands does not get tropical cyclones very often. Bangladesh gets the worst of them. There are geological differences between the regions that matter as well. Bangladesh is, essentially, a giant delta (I oversimplify slightly) which means that part of is is sinking all the time even while the sea level goes up. Flooding along rivers becomes a big problem with sea level rise. Both regions have rivers. Bangladesh, however, is a country made out of rivers, and among them is the Ganges, which is the world’s third largest river by discharge. Bangladesh probably has more problems with flooding than any other nation. In 1988, 75% of the entire country of Bangladesh was covered by a flood.
It is estimated that a 1 meter rise in sea level would take about 17.5%, or 25,000 square kilometers, of Bangladesh. I’m a little unsure of that estimate (and others I’ve seen) because different researchers count or don’t count large regions of the country that are already flooded by the sea. Another estimate gives 16% of the land to the sea with a 1.5 meter sea level rise. (You can explore various scenarios here if you like.) In any event, an 8 meter rise in sea level, which is expected long term, would take a very large part of the country, displace most of the population, and destroy most of the agricultural land. In case it is not obvious, let me note that as sea level rise threatens Bangladesh, it also threatens The Netherlands, which might keep the Dutch rather busy in their own homelands.
It is also important to note that sea level does not treat all coastlines equally. Some areas are being affected more than others. A report in CBS news recently noted, “Seas are rising more than twice as fast as the global average here in the Sundarbans, a low-lying delta region of about 200 islands in the Bay of Bengal where some 13 million impoverished Indians and Bangladeshis live. Tens of thousands … have already been left homeless, and scientists predict much of the Sundarbans could be underwater in 15 to 25 years.”
The Dutch reclaimed so much of the sea, and developed defenses against storm surges and flooding, over a period of centuries. During much of this time, The Netherlands was a major player in the European economic theater, acting as a center during the development of the world economic and colonial systems of the 17th and 18th centuries. To suggest that somehow Bangladesh can do what the Dutch did while the entire world is also busy adapting to sea level rise is absurd.
Peter Gleick of the Pacific Institute has done quite a bit of research on the potential effects of sea level rise, focusing on California (see, for example, Heberger M, Cooley H, Herrera P, Gleick P, Moore E (2009) The impacts of sea level rise on the California coast. California Climate Change Center, Sacramento, California. Paper CEC–500–2009–024-F). I asked him what he felt about the Lomborg interview. He said, “So a rich Dane tells poor Bangladeshis to stop whining and just ‘handle’ sea level rise, because that’s what the rich countries do? The reality, of course, is that even in rich countries, the poor will suffer most from sea-level rise. In our analysis of the risks to California from even modest SLR over the coming decades, nearly 500,000 people – disproportionately communities of color and low-income people – will be affected. And the cost of protecting them far exceeds the money available for coastal protection.”
There is also an absurdity to Lomborg’s assertion that we (our species) and Bangladesh (the country) should put off the global project of keeping the Carbon in the ground. We don’t know how long it takes for a warming planet to melt polar glaciers, but we do know that there is a pretty well established relationship between CO2 levels and global temperature, and between global temperature and sea levels. We know this from looking at numerous case studies from the past. It turns out that the relationship, ultimately, between CO2 levels and sea level rise is sigmoidal. Below about 400ppm, as CO2 levels rise, sea levels rise rapidly. Then, between about 400ppm and 650ppm, they rise more slowly, then above that level, the rate increases again.
Now, I want to pause for a second and clarify a very important point. We are now at 400ppm. This does not mean that sea levels will start to rise slowly. The expected sea level stand for 400ppm is probably close to 8 meters above the current level. In other words, the adjustment of sea level to CO2 that we expect should be very rapid, as fast as it generally goes (or nearly so) over coming decades. Once that level is reached, and CO2 continues to increase (and it will), then there may be a slowing down as we approach but have not yet reached about 650ppm.
So, what is absurd about Lomborg’s assertion? If we forestall efforts to keep the carbon in the ground for now, we will power through that range of decreased (but continuing) ultimate increase in sea level rise between the 400 and 650 levels of CO2, and nearly guarantee returning to the higher rate, and ultimately, seeing sea level rises in the tens of meters in coming centuries.
In his interview, as well as in a brief Twitter exchange we had, Lomborg made another error, one we often seen made by lesser informed people engaged in the climate or energy conversations. Lomborg seems to think that there is a fixed amount and class of resources and that one problem must be addressed at a time. But that is not how it works. First, there are resources primarily available for one thing such as public health, while other resources may be more generally applied. Also, we can in fact address more than one problem at once. I asked Professor Michael Mann, climate scientist, what he thought about Lomborg’s interview, and he told me, “Bjorn Lomborg is a master of the false choice, often claiming that dealing with climate change will somehow detract from our ability to deal with other societal problems. In reality, we can walk and chew gum at the same time. We can and must work on solving numerous societal problems. In reality, climate change exacerbates most of those problems. It is a threat multiplier. Lomborg conveniently ignores that!”
Speaking of the same problem, Peter Gleick told me, “Lomborg’s classic argument that other problems like disease are far more important than climate change and sea-level rise is a common Lomborgian false dilemma. Society can, regularly does, and must tackle multiple problems at once. This is like saying that because a patient has a broken arm the doctors shouldn’t treat her life-threatening pneumonia. Patently nonsense.”
I would add that increased flooding, decreased food supply, the mass exodus of people from inundated regions, etc. will create far more disease and starvation related public health problems than Bangladesh has at the moment. Forestalling or reducing the extent of this sort of disaster has to be a high priority.
Which brings us to the question of development. Bangladesh, like so many other countries, is likely to become more and more electric over time as it develops. Lomborg seems to want that to happen with the use of fossil fuels rather than clean energy sources. But, one of the obstacles to switching from fossil Carbon based energy to clean energy in the developed world is that our infrastructure is already set up to exploit mainly fossil Carbon based sources. In nations or regions where the use of energy is being developed every effort should be made to ensure this is done with clean energy. That is independent of any local or regional issues with sea level rise. This is what makes sense and this is what we have to do.
Lomborg is often wrong. I’ve noted this before (see: Are electric cars any good? Lomborg says no, but he’s wrong. and Bjørn Lomborg WSJ Op Ed Is Stunningly Wrong). Climate Hawks critiques Lomborg’s Bangladesh strategy here noting issues I did not cover above. Scientific American published a stunning takedown of Lomborg’s book here. Recently, Steven Newton of the National Center for Science Education expanded on that critique in a note about the support of Lomborg’s approach by the anti-science Discovery Intitute.
And in his statements on Bangladesh, he is wrong again.
ADDED: I’m adding a note to address, collectively and once, a number of comments that have been posted (some moderated) about scales of time.
This post is not about reconciling geological time with day to day time. I make as an assumption, in dealing with sea level rise, the idea that all recent estimates of polar glacial melt are at best minima, and fail to get at the real problem. I feel this is true because of my bias towards paleoclimate. I see in the ancient record changes in sea level stand that seem to occur over time periods that don’t look like a few mm a year of melting. I may be wrong, but the paleo record is pretty hard data while the melt estimates are a very preliminary stab at a very large problem that we are only starting to get a handle on.
This is not the point of the present post, but several commenters, who generally deny the importance of climate change and would prefer that we do nothing about it, seem to feel a) it does matters if large proportions of Bangladesh or other low lying countries are obliterated in 30 years or 300 years. The people who will be affected ten instead of 2 generations from now don’t matter; b) the ultimate multi meter rise in sea level, which will happen, is beyond their level of credulity, so they argue from that position that therefore a one meter rise in a region that is mostly about one meter above sea level does not matter; and c) feel that our ignorance of how to reconcile geological time scales of climate change in paleoclimate (mostly) is somehow evidence that there is not change; d) as usual, failure to accept the muddled yammering that arises from these starting points constitutes a lack of true scientific rational thinking, or a liberal bias, or some other such hogwash.
There is a handful of other annoyances that come with this group of deniers, but that’s mainly it. So, now, the questions you have had, are having now, or may have in the future, have been address in this area.
If you want a higher resolution copy of the graphic at the top of this post, click through to HERE then click on the graphic.
Other posts of interest:
Also of interest: In Search of Sungudogo: A novel of adventure and mystery, set in the Congo.
Climatology Versus Pseudoscience: Exposing the Failed Predictions of Global Warming Skeptics
Dana Nuccitelli is a key communicator in the climate change conversation. He is co-writer with John Abraham at the Climate Consensus – the 97% blog at the Guardian, and has contributed hundreds of entries to John Cook’s famous site SkepticalScience.com. He has measurably helped people to understand climate change science and the nuances of the false debate based over climate manufactured by science deniers.
And, he’s written a book!
It turns out it does! But you knew that. But what you might not have realized is the overall time frame of how this situation has developed. Dana skillfully documents the deeply disturbing fact that the issue of global warming (and related things) has been settled for a very long time. Were it not for mainly fossil fuel industry funded anti-science activists, we would not be having this discussion today, and Dana would not have had to write his book. Rather, science would be focused on figuring out the remaining and important details of how the Earth’s climate system responds to human pollution as well as natural changes, and policy makers would be busy working out how to keep the Carbon in the ground. We probably would have had a price on Carbon years ago, and we’d probably be running our civilizations off of a very high and ever increasing percentage of clean (non fossil carbon) energy. But no, those denialists had to ruin it for everyone with their fake skepticism.
I asked Dana Nuccitelli, “What surprised you most while researching and writing this book?” and he told me,
I was surprised at how accurate mainstream climate scientists’ predictions about global warming have been, even using the earliest global climate models as early as 43 years ago. The earliest model predictions were based mainly on the warming expected from the increasing greenhouse effect, so it goes to show what a dominant factor carbon pollution has played on global temperature changes over the past half century.
Climatology Versus Pseudoscience: Exposing the Failed Predictions of Global Warming Skeptics is engagingly written, clear, accurate, non-technical but not watered down. If you know the stuff in this book you can be more confident than ever having those conversations with with your friends Denialist Dan and Warmest Willie. In fact, I would recommend Climatology Versus Pseudoscience along side Michael Mann’s book The Hockey Stick and the Climate Wars: Dispatches from the Front Lines for a comprehensive treatment of the history of both denialism and the science itself.
I asked Dana who he had in mind as the most likely audience for this book. I’m sure it is for general readership, but I also felt it could be used in classes.
I wrote the book with the general public as my intended audience. I wanted to make explanations about some basic climate science concepts accessible to everyone. My publisher told me that they anticipate that universities and libraries will be the main purchasers of the book though, so they may have had class use in mind more than I did!
Dana covers the early days of climate science, discusses the “Astounding Accuracy of Early Climate Models (Chapter 3), discusses the development of the scientific consensus on climate change, and provides an excellent overview of the current situation with greenhouse gas pollution caused climate change.
Over the last year or so, it seems that the climate conversation is starting to shift. Major media outlets are changing their approach, not following the dictum of false balance. Climate change is starting to become a bigger factor in elections, in a good way. The President of the United States has openly called on Americans to reject science denialism. I asked Dana where he thought the climate change conversation might be going over the next couple of years, and if we might see addressing climate change as more routine rather than highly controversial in the future.
I think much of the media is starting to shift towards more accurate, responsible, and truly balanced coverage on climate change. The Washington Post has been doing a great job since they hired Chris Mooney. The Guardian’s climate coverage is excellent. TV media coverage has been improving, and some great shows like Years of Living Dangerously and Cosmos have tackled climate change.
I think journalists and producers are starting to understand the difference between false balance and actual balance in climate reporting, and that media shift will be critically important in accurately informing the public on this critical issue. Most people vastly underestimate the level of scientific consensus on human-caused global warming, and I think that can mostly be blamed on media false balance. If you regularly see one-on-one debates, it’s natural to assume the experts are divided and debating the issue at hand.
With human-caused global warming, that’s obviously no longer true, but that perceived debate explains why people still don’t view climate change as a top priority. That needs to change, but that won’t happen until we have truly balanced media coverage accurately informing the public. That was one of my key motivations in writing this book – to hold the climate contrarians accountable for their bad science and failed predictions, because so far the media has failed to do that.
Dana’s final chapter talks about the future, about what can and should happen. He notes that we have the technology in hand to solve the climate crisis, and that we are starting to apply it.
I strongly recommend this book for the general reader, but I would also suggest it for use in certain classes, either in high school or college. If you are a teacher and want to thoroughly cover the “Debate” over climate science, get this book.
Published by Praeger; 214 pages; copious notes; index; cool graphic.
And now, for a little video fun related to Dana’s book, climate science, and the scientific consensus on greenhouse gas pollution and its effects:
Dana on Typhoon Haiyan and Climate Change:
The Climate Consensus Project (John Cook, Dana “Nutelli” Nuccitelli, and others):
A typical climate science denier, John Spencer, talking about the Consensus Project. on “Andrew Neil vs Dana Nuccitelli”
What climate scientists and communicators do when they are not being challenged by climate contrarians:
Dana’s Ice environmentally thoughtful Ice Bucket Challenge: