This was technically difficult owing to internet conditions but interviewer Vijay Kishore Vaidyanathan did a great job with what he had. In particular he did a great job editing out the constant explosions in the background!
Tag Archives: Global Warming
Arctic Sea Ice Extent
Arctic Sea Ice extent continues to be a problem. This year, according to the National Snow and Ice Data Center, ARctic Sea ice reached its lowest extent this year on September 17th, which is about the sixth lowest extent on record, following a multi-year trend of decline. There is variation from year to year. This year’s minimum was almost exactly the same as last years. With the exception of 2001, minimum extent has been below the climatalogical average every year since 1998.
Dana Nuccitelli has a post on this with excellent discussion and some nice graphics, and he has also produced a new version of the animated “How ‘Skeptics’ View Arctic Sea Ice Decline” graphic, which I reproduce here:
When was the last 17 year long hiatus (pause) in global warming?
Some time in the 1970s.
I keep hearing about this 17 year long pause in global warming. So I went and looked. I did a regression analysis of the last 17 full years of surface temperatures from the GISS database. There is an upward trend in warming during this period and it is statistically significant.
Then I calculated a “running slope” over 17 year long periods from the beginning of the record (plus 8 years) to the end of the record (minus 8 years). For each slope I tested to see if the slope was less than +0.1 (the average slope across the record is 0.75). If a year centered on any 17 year period had a low or negative slope as defined, I counted it as a year in a Hiatus. I then made a chart showing when these hiatuses happened. They used to be more common, but it has been quite a while since the last one:
Since 2014 is not over yet, I did not include it. But, the last “year” (12 month interval) was the warmest 12 month interval for the entire record. 2014 is likely to be in the top two or three warmest years globally on record, quite possibly the warmest. That is not going to help the now discredited hiatus theory very much.
What can we do about climate change?
I could rephrase this question. What should we do about climate change. The reason I might rephrase this is because we may not be that sure of what we can do, but we should do something. Or, more accurately, some things. There are a lot of possible things we can do, and we have little time to do them. So, maybe we should do all of them for a while. We could spend years working out what the best three or four things we can do might be, and try to implement them. But there will be political opposition from the right, because the right is inexplicably opposed to any action that smells like environmentalism or something that Al Gore might suggest. There will be powerful and effective opposition by those who happen to own or control the vast fossil Carbon based reserves because they know that whatever it is we do about climate change, it will involve keeping their Carbon in the ground, which will render it nearly valueless. The very process of working out the handful of best solutions will falter because of those opposing action. So instead, maybe we should do a Gish Gallop of climate change action. Just do everything. Every thing. It will be harder to stop.
That is a pragmatic argument for doing everything, but there is also a more systematic rational argument. When new technologies, or new applications of technologies, emerge they often take an unexpected course. In retrospect, we realize that of a handful of options, the one we picked did not do what we thought it might do. It may have fell short of expectations, or it may have functioned in an unexpected and disruptive (in a good way) matter. Meanwhile, we sometimes see that the technologies we did not develop may have been better choices. In this way, technology and industry evolve. We don’t have time for this slow evolution, so may be we should do everything and later, after some of these solutions have run for a while, weed out those that are not working as well and focus on the newly adapted, evolved solutions.
Obviously when I say “everything” (or every thing) I don’t really mean every single thing; it is reasonable to pick and choose. But we need to take a much more comprehensive approach than often suggested. In the world of clean energy there are many (increasingly institutionalized) schemes with promotors who actually spend time and energy putting down the alternatives. Pro solar people will tell you bad things about wind, and pro wind people will tell you bad things about solar. Those who wish us to have a totally reformed and rebuilt transportation infrastructure will tell you that electric cars are not the way, even though their reimagined transport system is at best a century in the future, while shifting much of our vehicular fleet to inherently efficient electric cars could be done at at time scale of a few years. So, what I mean is, do every thing that is on the table, deployable, right now. Geothermal heating and cooling in domestic, commercial, and industrial settings. No roof should be without at least some photovoltaic panels. Build more windmills. Paint the roofs white in cities. Develop incentives for people to live closer to work or travel less by working from home. Electrify everything that moves from cars to city and school buses to commuter trains. Tax Carbon, provide tax or other incentives for the purchase of highly efficient appliances. All of it.
Lawrence Torcello and Michael Mann (philosopher and climate scientist) have an interesting piece at The Conversation integrating climate science, strategies, and philosophy. In part, they say,
…the warming level already reached will likely displace millions of people worldwide. Entire island cultures may be scattered and their traditional ways of life destroyed. Any resulting refugee crisis will be exacerbated by a greater range of agricultural pests, tropical diseases, increasingly frequent heat waves, wildfires, droughts, and subsequent crop failures. Migrating climate victims will be at risk of further injustice as social and political tensions intensify….
If we fail to avoid 2°C warming, a possibility we must be ready for, aggressive action taken now will still position the next generation to better build on our efforts—while learning from our mistakes. The difficulty of our situation is no excuse for moral dithering.
That is certainly a good way to sum up what our plan should be: Aggressive.
Mark Steyn and Judith Curry
Two items related only because these two seem to like each other and there are coeval happenings.
Mark Steyn and Dr. Michael Mann’s book
Michael mann wrote a great book called The Hockey Stick and the Climate Wars: Dispatches from the Front Lines. It really is a good book, I highly recommend it.
Mark Steyn is a right wing talking head and shock jocky guy whose behavior is that of a seventh grader. Since Mann’s book was published, numerous anti-science and anti-environment Internet trolls have posted bogus, harassing, one-star reviews on Amazon of Mann’s book. Often, these reviews come in groups and have had the appearance of a coordinated attack. In many cases, Amazon has recognized this and deleted those reviews.
Now we know that Mark Steyn is behind these attacks, or at least, he is behind an attack happening right now, not so subtly goading others to not only buy his own merchandise but to focus on Mann’s Amazon page. He has coordinated attacks on Mann before, such as his goading of his followers (and they really, truly are followers, which is probably not how they see themselves) to ruin a public Twitter discussion with Mann (hashtage #AskDrMann).
(I know how this works because it happened to me as well.)
If you’ve read “The Hockey Stick and the Climate Wars” and you’ve not left a review on the Amazon page, and you are concerned about climate change and the practice and politics of science denialism, then you need to know the lack of your voice is meaningful. Go speak up. Only if you’ve read the book, of course (and I’m sure you liked it)
Judith Curry In Denial
Not long ago Judith Curry wrote a rather appalling editorial for the Wall Street Journal. Just now, Michael Mann has published a resonse, “Curry Advocates Against Action on Climate Change.”
She ties her argument to a new study she has co-authored, as well as the global warming speed bump (or faux pause). Neither offers a compelling reason to avoid reducing emissions. Her study looks at recent temperatures and uses them to try and determine how much the atmosphere will warm from our CO2 emissions.
The result is a figure low enough for contrarians to trumpet, but still not really that far from the official figures provided by the UN’s IPCC, the gold standard of climate science. This is why the new study (and the others very similar to it) have elicited only a collective yawn from serious academia.
So the piece repeats the same tired claims about lowered sensitivity, using the “pause” meme and her own study as justification for delaying action.
We Just Had The Warmest September on Record
We have been having a run of very warm months, and according to the GISS database, updated yesterday, September was the warmest on record, and the records go back to the late 19th century. This is global average temperature of the surface.
I’ll have more about this later, as other databases are updated. Sometimes one data set shows slightly different results than others, so it is good to look at them all as a group. Also, NOAA has not updated its climate watcher thingie yet.
If October, November and December turn out to be very warm as well, 2014 will end up being one of the top three or four warmest years on record, despite a somewhat cold start.
Antarctic Sea Ice and Global Warming
Did you ever leave your freezer door slightly open on a humid day only to find chunks of new ice formed at the gap? When that happens, did you conclude “Oh, my freezer is colder than usual, I wonder how that happened?” No. You concluded that you had left the door slightly open, some cold got out, and vapor froze on your gasket.
Sea ice is hard to make. The sea is salt water, so it has a lower freezing point than fresh water. The sea has potentially large waves and lots of currents. This is just not a situation where ice can easily form. Yet, it does form on the oceans near the Earth’s poles because it is really cold there. But even within that context, more or less ice can form because of important details like how much fresh water is mixing in with the cold salt water, and exactly where currents of warmer or colder water are going. The formation of sea ice at the ends of the Earth is probably somewhat more complicated than the formation of frost and rind on your refrigerator.
(A quick note: Sea ice is ice that sits on, and therefore, essentially, in the sea. It is not glacial ice. Those are two very different things. I’m sure you knew that but just in case this is a good moment to point it out.)
In recent years, the amount of sea ice forming around Antarctica has bee going up. Global warming causes local warming but it also causes local cooling (like when the Arctic Vortex got knocked off center last winter and visited the middle of North America, an event that still causes a sense of fear and loathing among those of us who experienced it). So when we hear about expanding sea ice in the Antarctic, knowing that anthropogenic global warming is a real thing, we might assume that this is just one of those phenomena that runs counter to expectations but that is still part of the overall process of warming-driving climate change resulting from the addition of greenhouse gasses to the atmosphere.
And that is essentially correct, though the reasons may be a bit unclear and require further study.
So, thinking about our freezer, and the overall problem of making sea ice, there seem to be three things that can cause more of this ice. One might be the addition of fresh water to the system. That seems likely if the Antarctic glaciers are melting (which they are). Depending on where the fresh water goes, that could allow the formation of sea ice. Also, if precipitation increased in the area, that would add fresh water.
Second, the area where the sea ice is forming could be colder. That seems backwards in on a warming planet, but actually, that can happen too. Antarctica is, to a larger extent than the Arctic, a semi-closed system of air and sea currents, because it is a roundish continent surrounded by sea at one end of the planet. This means that cold air might be retained over the continent rather coherently. At the North Pole, “Winter (January) temperatures … can range from about ?43 °C (?45 °F) to ?26 °C (?15 °F), perhaps averaging around ?34 °C (?29 °F),” while at the South Pole, “In winter, the average temperature remains steady at around ?58 °C (?72 °F).” (source: Google). The north pole is sea, the south pole is land, and the south pole is at a higher elevation, but those differences are partly why the south pole is colder. Anyway, with all this cold air on the Southern Continent, perhaps one only needs to have air currents change a little to move that cold air over the sea a bit more to add to the chances of freezing water and making sea ice.
Third is the possibility that the disruptive effects of storms, waves, or surface currents could change, making for a calmer environment, allowing more ice formation.
Have any of these things happened?
Yes. Yes, they have.
Joe Romm has a writeup on some recent research that helps to explain the increase in Antarctic Sea ice (NOAA: Record Antarctic Sea Ice Growth Linked To Its Staggering Loss Of Land Ice).
The National Snow and Ice Data Center notes:
…sea ice surrounding the Antarctic continent reached its maximum extent on September 22 at 20.11 million square kilometers (7.76 million square miles). This is 1.54 million square kilometers (595,000 square miles) above the 1981 to 2010 average extent, which is nearly four standard deviations above average. Antarctic sea ice averaged 20.0 million square kilometers (7.72 million square miles) for the month of September. This new record extent follows consecutive record winter maximum extents in 2012 and 2013. The reasons for this recent rapid growth are not clear. Sea ice in Antarctica has remained at satellite-era record high daily levels for most of 2014.
“What we’re learning is, we have more to learn,” said Ted Scambos, lead scientist at NSIDC.
The unusual sea ice growth in Antarctica might be caused by changing wind patterns or recent ice sheet melt from warmer, deep ocean water reaching the coastline, according to scientists at NSIDC. The melt water freshens and cools the deep ocean layer, and it contributes to a cold surface layer surrounding Antarctica, creating conditions that favor ice growth.
From Skeptical Science:
The most common misconception regarding Antarctic sea ice is that sea ice is increasing because it’s cooling around Antarctica. The reality is the Southern Ocean surrounding Antarctica has shown strong warming over the same period that sea ice has been increasing. Globally from 1955 to 1995, oceans have been warming at 0.1°C per decade. In contrast, the Southern Ocean (specifically the region where Antarctic sea ice forms) has been warming at 0.17°C per decade. Not only is the Southern Ocean warming, it’s warming faster than the global trend. This warming trend is apparent in satellite measurements of temperature trends over Antarctica…
And, from NOAA:
Much of this year’s sea ice growth occurred late in the winter season, and weather records indicate that strong southerly winds blew over the Weddell Sea in mid-September 2014. Antarctica is a continent surrounded by open ocean. So unlike the Arctic, where surrounding landmasses constrain how much sea ice can expand, Antarctic sea ice can spread out over a bigger area. Winds blowing from the land toward the ocean encourage ice growth in the waters north of the continent.
Winds probably did not act alone to spur so much sea ice growth; melting land ice may have played a role. Most of Antarctica’s ice lies in the ice sheets that cover the continent, and in recent decades, that ice has been melting. Along the coastline, ice shelves float on the ocean surface, and much of the recent melt may be driven by warm water from the deep ocean rising and making contact with ice shelf undersides.
How does the melting of land ice matter to sea ice formation? The resulting meltwater is fresher than the seawater. As it mixes with the seawater, the meltwater makes the nearby seawater slightly less dense, and slightly closer to the freezing point than the ocean water below. This less dense seawater spreads out across the ocean surface surrounding the continent, forming a stable pool of surface water that is close to the freezing point, and close to the ice onto which it could freeze.
Added cold seems to be a factor. Added fresh water seems to be a factor. Changes in where cold air and relatively fresh water goes seems to be a factor. I don’t know about storminess and currents at the outer edge of ice formation.
The dramatic and steady increase in Antarctic Sea Ice is yet another example of the effects of climate change.
What is the role of the deep ocean in global warming? Climate science deniers get this wrong.
What is the role of the ocean’s abyss in global warming?1
I’ve already posted on a study published in Nature Climate change that shows that the amount of extra global warming related heat in the Southern Oceans is greater than previously thought. There is another paper in the same journal by Llovel et al, “Deep-ocean contribution to sea level and energy budget not detectable over the past decade.” This paper verifies previous research that the oceans absorb a lot of the excess heat, but looks specifically at the ocean below 2,000 meters, which the paper referrs to in places as “deep” but that we should probably call “abyssal.”1 The paper concludes that the abyss is not warming. This is bad news, because if it was warming the total effects of global warming on the surface would be potentially less, or at least, stretched out over a longer period of time. But, it is not unexpected news. We already suspected that the abyssal ocean does not absorb much of the surface heat, while the shallower ocean absorbs quite a bit.
Research done prior to 2012 (e.g. Hansen et al 2011) parceled out the energy imbalance the Earth experiences from anthropogenic global warming. The extra heat caused by AGW from 2004 to 2010 was divided among the upper ocean (71%), the deeep ocean (5%), with the rest going various other places (only 4% over land). The new paper suggests that the abyssal ocean takes up closer to zero heat.
There are three complexities you need to be aware of to interpret this finding. First is the complexity in the climate system, second is the complexity of the research itself, and third is the relatively straight forward statistical problem of assigning meaning to specific numbers. That third one is important for journalists and regular people to pay attention to, because the climate science denial community is already exploiting it to misrepresent this study.
This is a complex and difficult problem
We know that the vast majority of the extra heat resulting from global warming ends up in the ocean, and also, we know there is a lot of interaction between the ocean and the atmosphere, with heat that might otherwise add to the atmosphere seemingly entering the ocean on a regular basis, with some of it occasionally coming out in large quantitates during El Nino events. This relationship is expected to change over time as the ocean warms, as the transfer of heat between ocean and atmosphere depends in part on the relative difference between them. At some point it is likely that the degree to which the ocean takes up net heat will decrease if the ocean warms up beyond a certain point.
Over the medium and long term this matters a lot. Because of the ocean (and polar ice and a few other things) the effect of increasing greenhouse gasses is not instantaneous. If the Earth was a simple rock with no water, but a Nitrogen atmosphere with, say, 250ppm of CO2, the greenhouse effects of the CO2 would ensure that the atmosphere was at least a little warm. If we doubled the CO2 the atmosphere would warm further, and it would do so very quickly. A new equilibrium would be reached in a geological instant (a few years?). But with the ocean, that change is much slower slower (decades, perhaps many decades), because the ocean buffers the atmospheric change.
When heat goes into the ocean, it then moves around in the ocean because it disperses across the aqueous medium, and because water is always moving in currents or mixing. An El Nino is a change in the movement of water that has been warmed with contact with the surface, so that warm water that has been building up at depth over time changes its movement pattern and moves closer to the surface (and to a different horizontal location) where heat is released. That is one (especially large and important) example of the complex dynamic of atmosphere, ocean, and heat. Currents that move through the upper ocean then dive down to depth may move some of the surface heat to the deeper waters, especially where the currents have dived not just from cooling water (hot water would tend to go up, cold water would tend to go down) but because it is driven in “conveyor” systems which may run counter to expectations of where water should go when considering only local conditions, and especially, if the water is dropping because of an increase in salinity. Again, this is an example of the complexity of the system.
If we add a lot of CO2 to the atmosphere, the atmosphere will warm up, but because of the complexities cited above, it is hard to say how much or how long it will take. The ocean serves to slow the process down. In fact, it is quite possible that if the ocean would be so kind as to absorb a certain amount of this heat permanently, maybe global warming would be somewhat reduced. The ocean is potentially a way of stretching out the effects of global warming. But this effect is likely reduced if the abyssal ocean is not in the game.
Complexities in the research
Meanwhile the measurement of heat in the ocean has been very sparse. Over the last decade more measurements have been taken using new technology, but even that is not as good as we would like to understand what is going on at depth. So, when it comes to understanding heat in the ocean, we may sometimes feel like we are at sea. The two papers in this week’s Nature Climate Change are much more important as studies that calibrate or refine the process of measuring ocean heat dynamics under global warming than they are studies that change our view of global warming. Neither paper concludes anything unexpected, both provide important refinements to key numbers, exploiting the last decade of improved data collection.
One of the complexities is in the details of the Llovel et. al study as compared to the handful of previous related studies. One of the key numbers is the energy imbalance where the ocean absorbs extra AGW produced heat. Energy imbalance is measured in terms of Watts per m
So, we have changing quality of data, a data set that is growing incrementally over time, studies that look at slightly different time and space parameters. And, on top of this, we have the increasingly advanced methods of figuring this all out. Both of the Nature Climate Change studies used a combination of direct measurements of temperature at various depths, a measurement of the altitude of the top of the ocean (sea level) from highly accurate satellite instruments, and measures of the mass of the water in the ocean, from the GRAIL gravity research project. If the mass of the ocean stays the same (same number of water molecules) but the surface rises, that is from heat, and that allows an estimate of energy imbalance. If the ocean goes up more than it should from heat expansion, the extra may be from glacial melting. And that is the simple version.
Statistical reasoning
The statistical part of this is not really so complex. Well, it is, but the part I want to point out is not. Llovel et al concluded “Accounting for additional possible systematic uncertainties, the ocean below 2,000 m contributes ?0.13 ± 0.72 mm yr?1 to global sea-level rise and ?0.08 ± 0.43 W m?2 to Earth’s energy balance.” Sea level rise is close to 3 mm a year, so the abyss is decreasing sea level rise by close to 4%. And, the abyss is in negative energy balance, while the upper ocean is in positive energy balance.
But look at the numbers. –0.13 plus or minus 0.72. There is actually no way to say that the abyssal ocean is contributing negatively to sea level rise. Zero (or small positive numbers) are well within the range of statistical probability. For energy imbalance, –0.08 plus or minus 0.43. Again, zero and small positive numbers are well within the statistical range for this value.
But for some reason we see various individuals, including sadly at least one climate scientist (Judith Curry: “Evidence of deep ocean cooling?“), but mostly anti-science climate trolls, crowing that the “deep ocean” is cooling therefore we are not experiencing global warming. However, the truth is that the total amount of heat that is going into the ocean, instead of the atmosphere or other places, was thought to be large, is still known to be large, and in fact is larger than we were originally thinking (from these papers and several others that have come out recently). And, the contribution of the abyss ocean to both sea level rise and energy imbalance is statistically nil. It might be negative, it might be positive, but it is tiny either way. The deep ocean, on the other hand, is in strong positive energy balance.
1The terminology used in this discussion and some of the research papers (or reporting thereof) is a bit confused. Climate scientists have repeatedly said that heat is going into the “deep ocean” and this paper seems to say it is not. But it is. It is a matter of terminology. This is a source of confusion sometimes exploited by climate science denialists. A good way to define these terms is as follows:
Shallow ocean = 0-700 meters
Deep ocean = 700-2,000 meters
Abyss = > 2,000 meters
Hansen, J., Mki. Sato, P. Kharecha, and K. von Schuckmann, 2011: Earth’s energy imbalance and implications. Atmos. Chem. Phys., 11, 13421–13449, doi:10.5194/acp–11–13421–2011.
Llovel, W. J. K. Willis, F. W. Landerer, I. Fukumori. 2014. Deep-ocean contribution to sea level and energy budget not detectable over the past decade. Nature Climate Change, 5 October.
Improved Understanding of the Role of the Oceans in Global Warming
The sun warms the Earth’s surface. Additional greenhouse gases and associated positive feedbacks (like, additional additional greenhouse gasses) increase that effect. So, it gets warmer, and by “it” we mean the “surface” of the Earth. This is usually measured as the temperature near the surface across the land and the surface of the sea (Sea Surface Temperature or SST). But over 90% of the heat added by global warming goes into the ocean.
We know how much heat goes into the ocean (other than SST) two ways. One is direct measurements using equipment that samples water at depth, and the other is by super amazing precise measurements of how big the ocean is (reflected in the altitude of the surface), which increases as it heats up. Direct measurements are sparse and do not go back a long ways, and are very rare in the southern hemisphere compared to the northern hemisphere.
A paper just out in Nature Climate Change looks more closely at the Southern Hemisphere by combining direct measurements, estimates from ocean expansion, and some fancy modeling. The study suggests that the estimate of heat held in the upper 700 meters of the ocean in the Southern Hemisphere since 1970 was several percent too low owing to the lack of good data.
The study looks at the period from 1970 to 2004, prior to the deployment of some (but not yet sufficient) improved measurement technology. Study author Paul Durack notes, “Prior to 2004, research has been very limited by the poor measurement coverage. By using satellite data, along with a large suite of climate model simulations, our results suggest that global upper-ocean warming has been underestimated by 24 to 58 percent. The conclusion that warming has been underestimated agrees with previous studies, however, it’s the first … estimate [of] how much heat we’ve missed.”
This is a lot of heat. From the paper, “For perspective, these adjustments represent more than double the 1970?2004 heat storage change for all non?ocean (terrestrial, cryospheric and atmospheric) heat reservoirs combined…”
What does this mean?
It may mean that there is more heat added to the Earth’s surface than we thought there was, which means that any empirical estimates of the effects of global warming would need to be increased. But the real meaning may only be understood when we have a better handle on what happens to heat within the ocean, as shallow waters interact with deeper waters, and how the ocean as a system interacts with the atmosphere. And this heat, at this depth, does interact with the atmosphere. Despite the rather spectacular nature of this finding, its greatest significance is probably that it is a major step towards quantifying what may be the biggest single unknown related to climate change: what is happening in the ocean. It may, though this is subject to revision, increase the higher end of the estimate of “climate sensitivity” which is a measure of how much the surface of the earth will warm given a doubling of pre-industrial levels of atmospheric CO2. In that sense, this is potentially unpleasant news.
I have an FAQ on this research that I’m not sure I can provide a link for, but I’ll past the part that addresses the importance of the research, in the view of the authors:
What are the implications of long-term underestimates to ocean warming?
Quantifying how much heat is accumulating in the Earth system is critical to improving our understanding of climate change already underway and to better assess how much more we can expect in decades and centuries to come. Our key result is that the warming of the global ocean in recent decades has been substantially underestimated. These findings will likely lead to a revisit of previous sea-level and climate sensitivity estimates, and to a re-examination of how scientists deal with poorly sampled aspects of the climate system. A key lesson to be learned from our work is that observing the global ocean is critical, and that prior to the recent improvement in global coverage of ocean observations, a substantial and very important part of the global climate system was under-observed. In order to better understand past and future climate changes it is imperative that the global ocean is adequately observed, as it plays a critically important role in the Earth’s climate and its change.
I have a feeling there will be a lot of discussion of this over the next few days.
Explaining Extreme Events of 2013: Limitations of the BAMS Report
The American Meteorological Society, in it’s Bulletin of the American Meteorological Society (BAMS), has released a report called “Explaining Extreme Events of 2013 from a Climate Perspective.” Three studies looked at excessive heat in Australia, three at drought or dry conditions in California, and 14 looked at various other extreme events (though some of those events may overlap or be related) for a total of about 15 different phenomena.
There was a pattern in the results. The studies looking at heat all suggested a link to anthropogenic global warming (AGW). This is not surprising because AGW has involved a global increase in average temperature which is manifest across a variable climate, so even a modest increase in global temperature, bunched up in to places that are a bit cooler or warmer than average (at a given moment in time) is going to be blatantly obvious when picking out heat events. Some of the studies that looked at the California drought and drought in New Zealand attributed these conditions to climate change, others were more ambiguous or suggested that there was no link. All of the studies that looked at extreme precipitation events concluded that there was no way to make a connection, except one (in Northern India) which as ambiguous.
Michael Mann has pointed out that there is a basic problem with the BAMS study. Many of the extreme climate events of recent years have been linked by various researchers to climate change, but a) none of these researchers seem to have been invited to contribute to this collection of papers, and b) some of those specific events have been linked to climate change by some of those researchers.
It might be tempting to view this volume as an authoritative statement by the scientific community on the role climate change may or may not have had in some high profile, devastating recent extreme weather events. But that would be misguided. The BAMS special issue is not a representative, community-wide scientific assessment like those published by the National Academy of Sciences or the Intergovernmental Panel on Climate Change. The editors, instead, have solicited contributions from a relatively small number of groups, so the findings do not necessarily reflect the range of views of the broader scientific community. Some leading climate scientists who were not included in the effort have presented evidence of a greater role for climate change in several of the events dismissed or downplayed by the BAMS articles (see e.g. Kevin Trenberth of NCAR on the September 2013 Colorado floods, Stefan Rahmstorf of the University of Potsdam on the June 2013 Central European floods and Jennifer Francis of Rutgers on the 2013/2014 California Drought).
I’ve provided references and links to the studies mentioned by Mann, as well as other studies, below.
Mann points out, and I had noticed this when I first read the BAMS volume, that the studies that looked at extreme precipitation pretty much leave out the mechanism implicated by the above mentioned researchers. In fact, I would say that the basic methodology used to examine these events is flawed in two ways. Before describing that, here is summary information about the studies.
The spatial and temporal context of the studies, and attribution
In order to evaluate the studies in the BAM report, I ranked attribution from 1 to 5. 1 means no effect of climate change at all, 5 means climate change is a major contributor or THE explanation. 3 is the nickpoint; a 3 means maybe maybe not, or serious ambiguity. So 4 and 5 are yes, climate change mattered, 1 and 2 are no, climate change did not matter (but 1 is more strongly stated) and 3 means you can’t say but maybe.
The four studies that look at dryness and drought (including more than one for California so these are not all independent data in that respect) had attribution vales of 2, 3, 4, and 4. The minimum surface area of the climatic events evaluated was about 268,021 km2, and the maximum about 423,970 km2. These events are generally long term. Drought or dry periods are large and slow moving things, and the period of time over which they happen ranges from several months to years. Notably, some meteorologists such as Paul Douglas have noticed a shorter term event, which Douglas calls a “Flash Drought,” a period of little or no rain where there usually is some rain lasting for several weeks, sufficient to disrupt crop growing but not sufficient to lead to long term effects such as depletion of ground water supplies.
The 10 studies that looked at heat (all but one excessive heat, one cold) had attribution values of 1 (the cold in UK), 4, 4, 5, 5, 5, 5, 5, 5 and 5, with a surface area ranging from about 220,000 km2
to 133,453,480 km2. Heat waves usually cover large areas, but can be very short term, lasting several days to several weeks.
The 8 studies that looked at extreme precip (most rain, one snow) had attribution values of 1,1,1,1,1,2,3, and 3 … no case was attributed unambiguously to climate change, most not at all. These areas covered a region of between 27,980 km2 and 8,080,464 km2, but most clustered near the lower end of that range. Most extreme precipitation events cover small areas (though the extreme rain experienced during the summer of 2014 in North America may have been a physically very large event running form the Upper Plains to the Ohio Vally, and beyond). Extreme rain and snow storms normally occur over a matter of several days.
Spacial-temporal bias in the BAMS study
The size and lifespan of the events under consideration is the best single predictor of level of attribution given by the individuals studies. For the most part, relatively small short term events were not attributed to climate change, while large slow moving events were more often attributed to climate change. Exactly parallel to this is, of course, the nature of the event. It isn’t just the size and lifespan of the event, but the kind of event that matters, which in turn relates to the size and time frame. But, the size and lifespan of the precipitation events may be part of the explanation for why attribution is low.
This is why. The studies that looked at precipitation used a number of different approaches but for the most part they had the same characteristics. Underlying the application of the various analytical techniques is the question of probability. If a certain kind of event (a large amount of rainfall in one place over a contiguous number of days) is rare, and climate change makes is somewhat less rare, it may be impossible to detect this probabilistically unless the sampling is done right. It is difficult to measure, with statistical confidence, the difference between something that is very very rare vs. merely very rare. Since the studies essentially tried to do this (for the most part), it is not surprising the study results did not attribute those events to change over time.
It may the case that a year by year study of changes in probability of rare events will not detect a change until the change is huge.
And now for a brief thought experiment.
Imagine for a moment that all climate events are the result of the distribution and behavior of small imaginary objects that float around in the air. We’ll call them climaticulus. Climaticules have two attributes: temperature and moisture. Unspecified processes alter these attributes. If enough climaticules in a region are dry for long enough, you might get a drought. If enough are wet, you might get lots of rain or snow. If a lot are warm, you might get a heat wave.
With the climaticule thought-model, variation in two attributes can generate a spatially large long term event (like a drought) or a spatially concentrated short term event (like flooding rains). At the surface, these events look like qualitatively distinct events, but underlying them is a simple system. In this system, the smaller and shorter term events are going to present statistical distributions that are different than the statistical distributions of the larger scale events. Even if they are the same kind of distribution, they will be scaled very differently. It is quite possible that a numerical change in one category of event will remain invisible while others are latent, given similar basic approaches such as “what happened over a year’s time” or “what happened in a particular space.”
That thought experiment may or may not have been helpful, but I can put it another way: Under climate change, the climaticules are sending out a signal that results from changes in average temperature and moisture. When the signal comes as a large slow moving event, it is hard to miss. When it comes as a small ephemeral event, it is easy to miss.
Mechanistic bias in the BAMS study.
As pointed out by Mann (see above), the BAMs study fails to consider an already proposed and reasonably well supported mechanism for increased occurrence of extreme precipitation events. This is the change in the patterns of trade winds and jet streams that seems to result from regionally increased sea surface temperatures and/or relatively more warming in the Arctic.
Under normal conditions, in the northern Temperate zone, air masses move from west to east, between two jet streams. The jet streams guide the air masses and the air masses push around the jet stream … they can be thought of as two aspects of the same system that arises from a a combination of the Earth’s rotation and the movement of heat from equatorial regions north towards the pole.
Under these conditions, the air masses vary in barometric pressure and moisture, and this variation causes rainy atmosphere to move at the large scale from west to east at a fairly rapid clip. So if you are sitting there in Iowa, it might be sunny mid day, than a front comes through bringing some storms, then the sky clear again, over several hours. Or, you might get a larger, wetter, air mass coming along that brings a day of variable amounts of rain.
It is thought that recently it is more common for the jet stream to for giant curves, which relates to the temperate air masses bulging northwards or being pushed southwards. The jet stream slows down. So, air masses that might bring precipitation are either blocked from their west to east movement or move very slowly (and in a somewhat different direction) than they normally would. So, a stormy, wet, rainy air mass may take two or three times longer to move across a given region, causing much more rain to fall there. At the same time, other regions may experience long term lack of precipitation. This is all further complicated by the changes in where the air mostly comes from and goes to, allowing some air to be dryer than usual and other air to be wetter than usual. And, because of AGW, the air is on average warmer so it can hold more moisture.
So, you get a bunch of extra moist air arriving in a place where contact with colder air masses and changes in pressure cause it to be rain-producing, and it sticks around for several days in one spot, or moves very slowly, and you end up with flooding like we saw in Calgary, or Boulder, or long periods of continuous storm formation and rainfall over a large area like we had in the upper Midwest in June of 2014.
What was the jet stream doing for each of the studied extreme events?
Focusing only on temperate regions in the US and Europe, I assembled a set of wind stream maps (from here) that more or less show the behavior of the jet stream at the time of each event. These are a little hard to read but you will notice that the location of the event is in every case up against a wavy part of the jet stream at the time. For reference, I took one of the events, September 13th, and picked out several earlier wind stream maps (every five years for several decades in the past). This is not a systematic sample, but it shows that typically the jet stream, not so long ago, was flatter (probably) than it was during these extreme events. These graphics are all pasted below, and I’m sorry if it takes a while for them to load.
The examination of the relationship between climate change and extreme weather events is tricky, in in its infancy, but we are beyond the point where we should be ignoring emerging research pertaning to the link. The BAMS report ignores that research. Also, the examination of extreme precipitation events should be done in larger blocks of time than one year. Looking year by year, and event by event, almost guarantees not making the link because of the bias in spatial and temporal features of these events.
Colorado storm, September:
South Dakota Blizzard, October 4-5:
Wet southern European winter, 2013:
Heavy precipitation, May-June, Upper Danube and Elbe Basins:
Extreme snow, Western Spanish Pyrenees:
Violent Storm in Northern Germany and Denmark, 28 October:
For comparison, September 13th from several prior years:
1970:
1975:
1980:
1985:
Prior work related to climate change and extreme weather events:
Linking Weather Extremes to Global Warming
More Research Linking Global Warming To Bad Weather Events
Is Global Warming Behind the Polar Vortex?
Extreme Jet Stream Pattern Triggers Historic European Floods
Are you ready for more floods and wildfires?
Drunken Arctic Goes Head Over Heels
Interview With Climate Scientist Michael Mann
As you know, I do the occasional science-related interview on Minnesota Atheist Talk Radio, on Radio AM 950. (See this for a list of all, or at least most, of the work I’ve done with that show.)
On Sunday October 5th at the ungodly hour of 9:00 AM Central Time, I’ll be interviewing Michael Mann, and Mike Haubrich will host. There is plenty to talk about but if you have a specific topic you’d like to see covered, or a specific question, feel free to note it below in the comments section.
It is also possible to call in or send an email to the station during the show. Listen to the show and Mike will give details at that time. If you don’t happen to live in the listening range of the radio station, there may be ways to listen. I once found the show on the Roku, and it is possible to listen on line. I’ll let Mike Haurbrich post in the comments how to do that because I’m not sure my information is current.
The show will be a podcast available here or on iTunes.
Michael Mann is probably the most famous active climate scientist. In 1988/9, he and colleagues published a paper looking at recent and historical changes in surface temperatures, presenting a graph dubbed the “Hockey Stick” because it looked like a hockey sick laying on its back with its blade representing the rising cluster of warm temperature measurements following centuries of normal, cooler, temperatures. Climate scientists have carefully examined and expanded on this work since then. As a result, the hockey stick has been refined, expanded (back father in time), and verified by numerous studies. Meanwhile, those with an anti-climate science, or anti-global warming agenda have spent considerable effort trying to debunk the hockey stick, but have failed to do so. But they still think they have a case, and the “Hockey Stick Wars” have continued apace. Mann wrote “The Hockey Stick and the Climate Wars: Dispatches from the Front Lines” about that very conflict.
Michael Mann is Distinguished Professor of Meteorology in the departments of Meteorology and Geosciences at Penn State, and he is Director of Earth System Science Center. He has a B.A. in Physics and Applied Math from the University of California at Berkeley, an M.S. degree in Physics from Yale University, and a Ph.D. in Geology & Geophysics also from Yale. He was one of the lead authors on the IPCC’s Third Scientific Assessment Report in 2001. He is the recipient of NOAA’s outstanding publication award (2002). He is one of the scientists who contributed to the award of the 2007 Nobel Peace Prize. He received the Friend of the Planet Award from our friends at the National Center for Science Education, and is a Fellow of both the American Geophysical Union and the American Meteorological Society. He has authored over 170 scientific papers. More information can be found here.
Anti-Science NRO and CEI File New Briefs, Get It Wrong Again
This is about the law suit filed by Michael Mann against the Competitive Enterprise Institute, the National Review, Mark Steyn, and Rand Simberg because of accusations they made that were actionable. Michael Halpern summarized:
Competitive Enterprise Institute’s space technology and policy analyst, Rand Simberg, recently wrote a blog post in which he compared Penn State climate scientist Michael Mann to former university football coach and convicted child molester Jerry Sandusky. CEI published the post on its own blog, and the National Review decided it was appropriate to pass along. Michael Mann has rightly demanded that the National Review retract the blog post and issue a public apology.
The most offensive section of the CEI post, which has since been scrubbed:
“Mann could be said to be the Jerry Sandusky of climate science, except that instead of molesting children, he has molested and tortured data in the service of politicized science.”
There has been a lot of back and forth in the legal proceedings, and the latest is summarized by Aaron Huertas:
The latest round of legal briefs have been filed in climate scientist Michael Mann’s lawsuit against the National Review (NRO) and Competitive Enterprise Institute (CEI). …
NRO makes a distinction between calling Dr. Mann’s work “fraudulent” and alleging that he had, for instance, embezzled funds or fabricated raw data.
Indeed, there are gradations of accusations one can make against a researcher. Stating that a scientist is wrong in their analysis is a far cry from saying their work is shoddy, but both are normal parts of public discourse about science. It’s another thing entirely to accuse a scientist of manipulating data or knowingly using faulty methods to reach a pre-determined conclusion. …
The worst thing one can do to a scientist professionally is to accuse him or her of fraud. More commonly, scientists refer to fraud as “scientific misconduct” or “research misconduct.” …
While the original research Dr. Mann’s and his colleagues conducted 15 years ago was certainly subject to criticisms and scrutiny, it held up to that scrutiny, and nobody ever made the case that it was fraudulent.
…
CEI’s legal brief rehashes investigations of scientists after a hacker (or hackers) stole emails from them in 2009. …
Dr. Mann’s lawyers cite all the investigations in their brief. That makes sense since all the investigations are related and none found that Dr. Mann—or his colleagues—were guilty of scientific misconduct or fraud.
But CEI attempts to argue that these investigations were somehow insufficient. Regarding the two investigations that did focus specifically on Dr. Mann, CEI tries to downplay how serious they were. They write that Penn State’s committee looked at whether or not Dr. Mann “falsified data” and claimed that the “inquiry committee simply reviewed some of the [stolen] emails, spoke with Mann, and then dismissed it.” They also write the National Science Foundation “did not conduct an investigation of Mann’s data practices or research because it determined that ‘no direct evidence has been presented that indicates the Subject fabricated the raw data he used for his research or falsified his results.’”
…In reality, these investigations were far more thorough than CEI suggests. …These latest filings only reinforce my view that attacks against Dr. Mann are ideological and political in nature, not based on an actual assessment of his work.
You can read the rest, and more detail, here.
As you may know, we have been having a lengthy discussion here about the original work done by Mann and his colleagues. Feel free to join in! Regarding the research itself, this is very simple. Mann and his colleagues attempted to look simultaneously at some “paleorecords” … indications from ancient sources of temperature … and the modern “instrumental record” (i.e., from thermometers) to see if the already observed increase in temperatures thought to be linked to anthropogenic global warming really does stick out like a sore thumb among temperatures going back longer in time. The result of that study was, essentially, a graph combining ancient data and modern data that looked like a hockey stick laying on its back:
There are three ways in which this research could be questioned. First, it was only of the Northern Hemisphere, not global. Second, it is possible that the particular observations of modern temperature, the instrumental record, was somehow incorrect or biased. Third, it is possible that even though this graph shows the modern increase in temperatures as extreme, maybe the older data is bad, or maybe if you went back further in time (and globally) you’d find pre-industrial (prior to the release of so much carbon dioxide into the atmosphere) periods that are warmer than today, suggesting that the underlying assumption of how greenhouse gases might be wrong.
Even at the time, though, these objections were weak. While the Norther and Southern Hemispheres may (and do) act somewhat differently from each other, they are not as out of sync as they would have to be for the basic hockey stick graph to be wrong. The instrumental data was certainly not as perfect as one might like, but it was pretty darn good data. For the last few million years, during the course of human evolution and the evolution of our current ecology, there was no reason to believe that there were periods much warmer than today, if at all.
But subsequent research was done, of course, and several findings support, refine, and expand on the hockey stick model. Additional studies of modern temperatures showed results very similar to the data used by Mann and colleagues. At least two studies look at biases (one looked at the possibility of false warming caused by urban heat island effects, another looked at areas of the Earth that are under-sampled by direct observation). Both found that the hockey stick curve was either pretty much correct for instrumental data, or actually possibly a bit lower in temperature than reality.
Of course, the entire study was extended globally, confirming this as a global pattern.
Work on paleo information extended the range of the hockey stick graph way back in time, and showed that during the Holocene (last 10,000 years) there was not a period warmer than today. Further work seems to indicate that even during among interglacial periods (we are in an interglacial now) things are warmer now than usual. It turns out that you almost certaily have to go back in time several hundred thousand years, possibly several million years, to get a time period as warm as today.
Most importantly, per has, as time has passed since the original hockey stick curve was produced, the globe has gotten warmer. The air and sea surface are warmer, though the amount of warming has been modest compared to what we would expect for a simple model where greenhouse gasses only warm the atmosphere. But a lot of heat is being absorbed by the ocean, it turns out. The true surface temperature of the planet has to include both the atmosphere and the ocean (both surface and at depth) and we think over 95% of the extra heat from global warming goes into the deep ocean, but it is not well measured.
Meanwhile the whole “Hockey Stick” controversy continued and developed. This isn’t just a couple of people and a major conservative publication falsely accusing Michael Mann of fraudulent behavior (scientific misconduct). Anti-science forces have spent millions of dollars attempting, usually very clumsily, climate science, and one or more individuals went so far as to steal emails among climate scientist, falsifying using cherry picking what was said in those emails. It is an all out war between anti-science and anti-environment groups and individuals on one hand vs. scientists and rightfully concerned citizens on the other. A great description of how these “Hockey Stick Wars” played out can be found in this book.
How Melty Was The Arctic Sea This Year?
The Arctic Sea is covered with ice during the winter, and some of it melts off every summer. Over recent years the amount of melt has been increasing. This is the time of year we may want to look at Arctic Sea ice because by late September it has reached its annual minimum and is starting to reform.
Looking at JUST surface area, which is one indicator of how warm the Arctic has become with Global Warming, we can see (above) that this years march of melting has been extreme, hugging the two standard deviation limit for all of the data from 1979 to 2010 (almost the present).
Here you can see that 2014 is distinctly different, with much more surface area loss, than the first ten years of this data set, from here.
And here you can see that 2014 is pretty much in the middle of the range for the “new normal” as represented by the most recent ten years:
So, in answer to the question above, 2014 was a very melty year in the Arctic, though over very recent years there have been worse years. This year is about the sixth lowest minimum extent since 1979 or before.
Thinking Big About Clean Energy
I want to put a solar panel on my roof so that I am releasing less greenhouse gas into the environment. But then I hear that manufacturing solar panels causes the release of greenhouse gasses, so I have to subtract that from the good I think I’m doing. But then I realize that the people who are making the solar panels have to change their method so they release less greenhouse gas into the environment.
We hear this argument all the time (for example, here). You think you are doing something “green” but it really isn’t green because yadayadayada. I am suspicious of these arguments because they often (though not always) come from people who want us all to keep using fossil Carbon based fuels, for some (unsupportable) reason or another. One might think that these arguments have to be addressed in order to do a rational and well thought out analysis of the decisions you make.
But that is simply not true for three reasons.
Reason One: So what? Nobody tells me I have to make a rational decision about buying the 72 inch wide TV to replace my 64 inch wide TV, but suddenly I’m a bad person if I don’t do a detailed Carbon-based cost benefit analysis when I want to do something EVEN COOLER than having a bigger TV, like putting a freakin’ cool solar panel on my roof? Excuse me, but STFU with our rational argument yammering.
Reason Two: You can’t count. If I put a solar panel on my roof, almost no one is going to discount the value of my house because it gets some free electricity, but a significant number of people are going to pay more for it when I sell it because it is cool. See reason one.
So when I put these together, my personal cost benefit analysis leans towards doing it more than the nay sayers might say. But still, if putting up a solar panel kills more polar bears than not putting up a solar panel, because the manufacturers of solar panels use thousand of tons of coal per square inch of solar panel, I’ve got to consider not doing it. Except for reason three.
Reason Three: If we all refuse to act until everyone else acts than we will not act. I will buy whatever solar panel I want, and the people who make solar panels can compete for my business by getting the energy to make their solar panels from … solar panels! Or not. Eventually they will because we ALL have to stop using ALL of the Carbon. Driving an electric car in a region where more coal is used to make electricity, would have to be MUCH less efficient than not driving the electric car (in terms of carbon release) to make me think twice about it. I’ll drive my electric car and at the same time we’ll watch the electricity companies make more and more of their electricity from wind and solar, and they will have a bigger market to sell that in because we are locally replacing gas with electricity. Of course, I will need the electric car to get cheaper before I can get one, but if I had one, that is what I would be thinking.
I’ve had conversations about this issue with a lot of people and these conversations have made me realize that the structural argument against clean energy is wrong for the reasons stated above. It turns out that A. Siegel has had similar arguments and he has had similar thought. It is possible that he and I have even talked about this and are pretty much on the same page. Go read To solar carport or not to carport, that is the (or at least a) question … and see what you think!
The naysayers want you to think small, but they make it look like thinking big. Instead of just calculating the immediate costs, consider also the distant polar bears crushed by the wheels of industry because you want a solar panel, they advise! But no, think even bigger. Think not only along dimensions of production and supply, but also, time and socioeconomic change. In order to address the climate crisis, we have to keep the Carbon in the ground. In order to keep the Carbon in the ground, everybody has to do everything they can do all the time, and not sit on their hands waiting for some other guy to change a value in our spreadsheet. Think big.