I’m going out on a limb here. 2014 has been a very warm year. We’ve had a number of record setting months. But, a couple of months were also coolish, and November was one of them. December started out cool (like November ended) globally, but actually over the last few days the global average temperature has been going up. But, unless December gets really warm really fast, is is probably true that we will break some records but not all. This entire discussion, however, is problematic for a number of reasons.
How much does one year matter?
How warm or cold a given year is does not matter much for the overall trend. The upward march of global surface temperature is squiggly, but on average upward. Expect variation. Decadal trends are more important and more relevant. Global warming is continuing at the surface (sea surface and land based thermometers).
The graph above is a quick and dirty depiction of warming, using NASA’s GISS temperature record. The Y axis scale is anomaly in hundreds of degrees C, the X axis is months since the beginning of a 12 month moving average from January 1980. The point is just to show a) the increase in temperature just over the last few decades and b) how it squiggles up and down. We appear to be in an upward squiggle at the moment.
There are multiple temperature records
There are multiple “records” and they are assembled in slightly different ways and thus have slightly different data. They all show the same long term warming, and they all tend to correlate with each other. But they are slightly different. Some databases probably under-sample certain regions, for example. If we have a year that is very warm in relation to the most recent “hottest” year, it is unlikely to be so much warmer that it blows the previous record away by a huge number. Actually, that could happen, but it is more likely that some of the data sets are going to break the record while others do not.
Warmest year since when?
Not so much related to this specific year but important to keep in mind: This is the instrumental record. When we speak of record breaking years, we are usually comparing a particular year (like 2014) to each and every other year in a database that has been assembled from instrumental measurements. These databases variously go back in time to some point in the 19th century. They all start after CO2 was being release into the atmosphere at levels that probably matter, but way before the huge increase that has caused our present climate crisis. So, the instrumental records do measure, and as it turns out, demonstrate global warming. When we try to extend this record back in time, we lose track of variation in two ways. First, the proxyindicators (indirect measurements) used to estimate what the instruments would say were there instruments (and a time machine, presumably) have their own variation, so a number from ancient times is not perfectly comparable to a measurement from, say, 2013. Second, there is variation and conflation across time. We generally can’t point to a particular datum on a long term squiggle of global temperature from ancient times and say it represents a particular year.
What we can say is that for a particular period of time in the past the likely range of annual temperatures then was such that a given number (like, for example, this year’s annual global average) would likely be outside that range. When we do this, all of the recent years of global surface temperature are very very unlikely to have been exceeded by any actual annual temperature since the last interglacial (over 100,000 years ago). Most of the last one to two million years have seen mostly glacial and occasional interglacial conditions, but with the difference between those to climate settings increasing more recently and being less in the more distant past. It is possible that some years during interglacials over the last one or two million years exceeded our current warm temperatures (of the last couple of decades) but not many. As you go back in time, the chances of that increase because it was a bit warmer. For various reasons we are more confident about the last 800,000 years or so (as having few if any warmer years). When you get back to two to three million years there were time periods that may well have had lots of years warmer than the 21st century to date average. To get to consistent temperatures, for most years, warmer than present, you probably have to go back father.
So, we have this sentence: “2014 is the first or second warmest year since _______ .” That will likely be what we can say in a few weeks, after the data are measured, collected, processed, and made available. Or, we may be able to change that sentence to “2014 is the warmest since _____ in all of our instrumental records” or perhaps “2014 is the warmest since _____ in X out of Y of our instrumental records.”
Filling in the blank involves inserting the first year of the relevant instrumental records (such as “1880”) but it can also be filled in with older dated depending on how we feel about variation in the older, proxyindicator records. But it should also be rewritten a bit to include the probabilistic component.
This is just the surface temperature and does not reflect the totality of planetary warming
Personally, I think we should try to refer to these numbers as “surface warming” or the “surface temperature” and continuously remind people that this is only part of the story. How do you measure your body temperature? A thermometer stuck in an orifice will do. Or one of those magical strips on the forehead. Or an ear thermometer. But these are all surface measurements of your body and are subject to error or variation. The better measurement is the one the medical examiner uses in estimating time of death; stick the thermometer into the liver (they have special pointy thermometers for this purpose, and only do it on dead people.)
The Earth’s liver is the ocean. Well, not exactly, but the majority of extra heat that happens because of the increased greenhouse effect caused mainly by human added CO2 ends up in the top 2,000 meters of the ocean (see this for a recent paper on the topic). At medium scales of time, the surface temperature does a good job of tracking the Earth’s temperature, but heat moves, to different degrees at different times, between the air and the sea, so on a year to year basis it is a rougher approximation. But it is the best approximation we’ve got, so we use it.
El Niño
Some of my colleagues have been snarking about changing the name “El Niño” to “El Annoyingo” or something like that. We are expecting an El Niño. We’ve been expecting it off and on for months. It has been a long time since a major El Niño, perhaps longer than we’ve ever had since good records have been kept. The Pacific Ocean looks very El Niño like in some ways but it is not an official El Niño. Whether or not you have an El Niño is something of a continuum.
It is generally felt that the effects of a coming El Niño are not particularly influencing the 2014 average global temperature, but if a real live El Niño emerges over the next few months, next year will be the record breaking year, as opposed to this year. Or both, one right after the other.
Other commentary
Most of the climate bloggers and publicly conversing scientists I know were probably planning to not talk about 2014 as a “warmest” or “second warmest” or “record breaking” year until after the data are in. But a couple of major news outlets have started talking about it, so now we are seeing some conversation on the topic and I’ve posted links below to some of that. I probably wouldn’t have written this post (until January) had major media not started to chime in a bit prematurely. I think it was a mistake for major media to start talking about 2014 as a warmest year when close to 10% of the data were not in, the journos were looking only at one or two data sets, and to a large extent we are talking about weather not climate. Mark my words: If 2014 turns out to be second warmest in the majority of data sets, climate science deniers will make the claim that “they claimed it would be the warmest year, but it wasn’t. Checkmate, climate change!”
CNN’s premature claim: NOAA: 2014 is shaping up as hottest year on record
BBC’s premature claim: UN climate talks begin as global temperatures break records
Reuter’s premature claim: U.S., British data show 2014 could be hottest year on record
Sensible blogging on the topic:
<li><a href="http://climatecrocks.com/2014/12/03/tallying-2014-closing-in-on-a-record/">Tallying 2014: Closing in on a Record?</a></li>
<li><a href="https://www.wmo.int/pages/mediacentre/press_releases/pr_1009_en.html">2014 on course to be one of hottest, possibly hottest, on record Exceptional heat and flooding in many parts of the world</a></li>
<li><a href="http://tamino.wordpress.com/2014/12/04/a-pause-or-not-a-pause-that-is-the-question/">A pause or not a pause, that is the question.</a></li>
Have you read the breakthrough novel of the year? When you are done with that, try:
or Paperback
*Please note:
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What I find especially disturbing is that 2014 hasn’t been an El Niño year. This seems to be evidence of a strengthened warming trend.
It’ll be interesting to see how the year end data affects the “no warming since…” claim.
(By the way, today’s Washington Post has a good article on Antarctica.
http://www.washingtonpost.com/news/morning-mix/wp/2014/12/03/this-west-antarctic-region-sheds-a-mount-everest-sized-amount-of-ice-every-two-years-study-says/?tid=hp_mm&hpid=z4
My impression is that the printed American mainstream press is covering climate change more extensively and more accurately than before.)
They are starting to get on board.
Mark my words: If 2014 turns out to be second warmest in the majority of data sets, climate science deniers will make the claim that “they claimed it would be the warmest year, but it wasn’t. Checkmate, climate change!”
No argument there. I would add that those denialist claims will somehow work in references to the stories from CNN, the BBC, and Reuters as evidence of fear-mongering by the “socialist scientists pushing the science change agenda”.
“November 2014 was the second warmest November in the 36-year global satellite temperature record, according to Dr. John Christy…at the University of Alabama in Huntsville. With a global average temperature that was 0.33C (about 0.60 degrees Fahrenheit) warmer than seasonal norms. November 2014 trailed only November 2009…”
So, we know what to expect from the other data sets…
Didn’t this actually start with NOAA projections? http://thinkprogress.org/climate/2014/11/20/3594961/hottest-october-on-record-globally/
Where do you get this from? November was not coolish in UAH.
Chris, there are multiple data sets and they are not all the same at this fine level of distinction.
Climatehawk1, that was a monthly update; there have been “it’s looking like a warm year” commentaries since the September data, IIRC. And it may well be.
SSME: That sounds about right. the problem is, to get 2014 to the warmest year, with a couple of cool months, we need November to be warmer than second.
Australia has had it’s warmest spring (SON) on record.
I do agree, why on earth are we talking about individual warm years, it is hardly relevant compared to the error bounds in those yearly measurements.
I feel it is a reaction to the “no warming for 18 years” type headlines.
There was strong warming from about 1980 to 2000, and about no trend since 2000. But by fitting a single line from 1980 to the present, the trend will always be positive. If there is no increase in warming for the next hundred years, the trend will still be positive. In fact, if cooling sets in the single line fit to the data would remain positive until the temperature gets below that of 1980 and stays there. The remarkable scientific result is that global warming will persist in the face of substantial cooling.
CO2 theory was sold on the basis of CO2 dominating climate, because all other explanations for the warming from 1980 to 2000 were ruled out. Now an 18 year pause is just weather. Why wasn’t the rise just weather?
Roy. First, try looking at a line that runs from 1880 to the present. Then try to explain that away.
Second, explain how the physics of greenhouse gasses is wrong. Use math. You’ll need it to make you rcase.
Third, you can pick periods of time to make any point since there is variation in the system. See this: http://www.skepticalscience.com/graphics.php?g=47
Fourth, this: http://scienceblogs.com/gregladen/2014/11/14/continued-global-warming-in-the-midst-of-natural-climate-fluctuations/
OK, does that mean it was RSS? Are you trying to make the point that even though it may turn out to be just the warmest by an insignificant amount in GIStemp, say 0.01 or 0.02, it’s not likely to be warmest in every estimate. And even just the 0.01 or 0.02 in GIStemp (after 4 years since the previous record) is not something that deserves to be pushed.
You cannot assume there is a pause: http://tamino.wordpress.com/2014/12/04/a-pause-or-not-a-pause-that-is-the-question/
There is no statistically significant slowdown in the rate of global warming.
I agree that this will probably be the 2nd warmest calendar year ever.
There is no intrinsic merit in calendar year records.
But it will be amusing to stuff it to deniers and their “global warming stopped x years ago” mythology.
Toby; right, that’s why the graph above uses a 12 month running average.
Supplementing Chris O’Neill at #12, RealClimate’s latest post:
Hmm … A TV panel show the other night actually stated as fact (if memory serves maybe they fudged an added an “almost certain to be” or something in there but still) that 2014 was going to be the hottest year on record ever.
I assuming Roy Latham’s comment was a misunderstanding and not an attempt at distraction
http://scienceblogs.com/gregladen/2014/12/03/2014-will-not-be-the-warmest-year-on-record-but-global-warming-is-still-real/#comment-617430
A trend line isn’t just drawn from one point to another. A mathematical technique (Least squares?) is used to draw a line that minimises its difference from ALL the points.
So if the global average temperature does cool significantly for a significant amount of time, the trend line will indeed go negative. Isn’t science wonderful?
I enjoyed reading this fairly written article until the very end, when the highly objectionable phrase “climate science deniers” was mentioned.
I gather that encompasses anyone who’s sceptical of CAGW.
Sorry, Greg, ad hominem doesn’t impress..
This is a term of art in science communication, most people know what it means. Even NPR uses the term now. Denialism is objectionable. Noting denialism is sad reality.
I’ve always looked at “denier” as an appropriate description of someone who is “in denial.” Looked at in that light, it is actually bending over backwards to be polite, since it ascribes behavior to a psychological state rather than the less-than-honorable motives which characterize some who deny climate science.
Earthling:
I don’t know about anyone. That tends to include a lot of different people. However, anyone who says there has been no warming in X years where is their favorite number is clearly a denialist and there are plenty of those people around.
By the way, try to learn the difference between ad hominem and insult. I like this example from https://bookofbadarguments.com/?view=allpages :
“Your ad hominem attacks are evidence that your arguments are baseless,” wrote user226. Rodney began typing his reply “You appear to be too stupid to understand the difference between an insult and an ad hominem attack.”
Evolution, weakened mutated DNA, is caused by iron poisoning. The synthesis of toxic, malformed proteins requires a host with an iron supply. Toxic proteins: cancer, tumors, inflammation, degenerative conditions, diabetes, heart-cardiovascular disease, masses, lung C.O.P.D.,
dementia. These are just some of the main problem areas that correlate to iron deposits.
Global warming is used in conjunction with evolution to covertly describe the effects of iron poisoning. Rising CO2 levels is found in iron poisoned blood; the body’s defense mechanism to buffer the high levels of oxygen caused by iron. Iron attracts oxygen, causing free radicals, expediting
the aging & death process. The extermination plan, NOT extinction, is causing disease & deaths.
http://www.unveilingthem.com/
cab
From the Oxford dictionary: Denialist:
“A person who does not acknowledge the truth of a concept or proposition that is supported by the majority of scientific or historical evidence; a denier:”
Example sentence for the non “denialism” (same source as above)
“There’s big money to be made in climate change denialism.”
Earthling, it sounds like your objection isn’t valid.
Climate liars.
> Climate liars.
Yes, that thought had definitely crossed my mind. 🙂
“I enjoyed reading this fairly written article until the very end, when the highly objectionable phrase “climate science deniers” was mentioned. I gather that encompasses anyone who’s sceptical of CAGW.”
No, it encompasses anyone who denies the large and diverse body of scientific research results that have provided us with ample evidence of the need to institute and enforce policies to mitigate what the research indicates will be our consequences of failing to do so.
…Including failing to do so for politically-motivated reasons. (Mother Nature does not care how fervently you believe in your adopted political agendas or how closely you follow your leaders’ media pronouncements; your consequences will still arrive.)
There is nothing ad hominem there. (Not even anything insulting. Just a prediction of a well-defined group’s reaction.)
Sometimes you really do attract some interesting, uhm, nutcases, Greg! Earthling is just insulted, because he knows he is one of the people meant with climate science deniers – because he rejects just about all climate science.
But Bouthillier definitely wins first prize. I recommend you go to his website, just to have a laugh at first, and then feel some sympathy for the poor lad. Few people are so out of touch with reality. In the meantime, I recommend people not to get too worried about that “iron poisoning” of their blood. It would be a bit problematic if you did not have iron in your blood. And with “a bit problematic” I mean “you will die”.
“Do you realize that in addition to adding iron to our water, why, there are studies underway to put iron in salt, flour, fruit juices, soup, sugar, milk, ice cream? Ice cream, Mandrake? Children’s ice cream!…You know when iron fortification began?…1946. 1946, Mandrake. How does that coincide with your post-war Commie conspiracy, huh? It’s incredibly obvious, isn’t it? A foreign substance is introduced into our precious bodily fluids without the knowledge of the individual, and certainly without any choice. That’s the way your hard-core Commie works.”
“But Bouthillier definitely wins first prize.””
He has quite the reputation: copper deficiency causes blood types, ebola and measles are somehow linked to iron, and it’s all tied to some grand scheme to kill off – well, it isn’t clear exactly who will be killed off in the extermination plan. Apparently it’s a lot of people though.
“Iron is the most monstrously conceived and dangerous communist plot we have ever had to face. I can no longer sit back and allow Communist infiltration, Communist indoctrination, Communist subversion and the international Communist conspiracy to sap and impurify all of our precious bodily fluids…”
Isn’t mandrake a plant from the Harry Potter series?
Yes, and prior to his acting career in the HP series, he also served as U.S. President Merkin Muffley in the 1960’s…
I found some documentary footage from his administration…
https://www.youtube.com/watch?v=iAHJCPoWCC8
https://www.youtube.com/watch?v=Qr2bSL5VQgM
https://www.youtube.com/watch?v=qjN9yK4lhxU
@31. Greg Laden : Isn’t mandrake a plant from the Harry Potter series?”
It goes back way beyond the Harry Potter series – a legendary plant with a long history indeed :
http://en.wikipedia.org/wiki/Mandrake_(plant)
Gets mentions in Shakespeare, the Bible and Josephus among many more – including, yes, Harry Potter. (J.K. Rowling didn’t invent dragons either! 😉 )
Go and catch a falling star,
Get with child a mandrake root,
Tell me where all past years are,
Or who cleft the Devil’s foot … –John Donne
You mean it didn’t begin with Mandrake Linux???
Another way of looking at the warmest year: https://twitter.com/billmckibben/status/536176716733874176
Harder to knock this one down.
Yeah, yeah I was aware of the mandrakes.
Regarding the 12 month period; two problems. First, it is cherry picking unless you refer to the last 12 months EVERY month. Second, it still depends on the data set you use.
The November GISS data is in, and it’s going to be very close whether 2014 edges out 2010 or comes in a close second – far too close to matter. It’s going to have been a very warm year.
Wow, the Bouthillier site is really something – did you know U.S. population peaked around 1980, and is currently down to 200 million? Wouldn’t know it from where I live …
Here is another way of looking at the graph above that may be useful in addressing deniers: http://rabett.blogspot.com/2014/12/plenty-of-trend-at-bottom.html
The average for the year so far (through November) in GIS is higher than the previous average year.
climatehawk1.
Interesting chart from Rabett Run.
I wonder if the maximum peaks define a ‘resistance level’, like what the technical analysis people use. In that case I wonder where the next “resistance level” is.
Just a thought.
PS just after I had the thought, I realised others had already commented about it.
“A resistance level is the opposite of a support level. It is where the price tends to find resistance as it is going up. This means the price is more likely to “bounce” off this level rather than break through it. However, once the price has passed this level, by an amount exceeding some noise, it is likely that it will continue rising until it finds another resistance level”
I’m not sure that analogy is too helpful. We are talking about a shift towards an equilibrium. We are currently at disequilibrium. A better analogy would be this: In 1850 the true value of a stock 1 dollar a share, but it varies around that. In 2100 the true value of the stock is going to be4 dollars a share. Between 1850 and 2100 the market value of the stock is likely to move from about 1 dollar a share to about 4 dollars a share. The factors that affect the rate are somewhat vague and not as well understood as we like, but we expect it to get there some time between 2035 and 2100. The variations from year to year are understandable and measurable at the short term level but you can’t say what will happen a few years out.
The media are touting this “warmest yewar..” thing specifically because the deniers can’t stop touting their own idiotic “no warming since…”.
This is what the media love to do: controversy.
In this case, they aim to make the deniers look stupid, but they aren’t doing it because they actually want people to be educated, they just like seeing people contradict each other.
Right. Try to keep the ball in the middle of the court.
Japanese Meteorological Agency have released their November 2014 figures – 7th warmest. The GISS figures were are 5th warmest.
http://ds.data.jma.go.jp/tcc/tcc/products/gwp/temp/nov_wld.html
Still on track, it seems: http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2880
Oops: http://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/dec/17/2014-will-be-the-hottest-year-on-record I might just add, I don’t really think we should be driven by deniers’ reaction. I’m guessing that when 2014 is declared warmest, they will claim the measurements have been falsified.
Wow, you would almost think that the commenters here were glad that the world was warming and that this, if unchecked, would bring about a global catastrophe.
Surely not? A slowdown in warming would be news right?
We could have stated, quite accurately, that various years in the 1930s were the warmest on record, same goes for the 1910s, this means absolutely nothing. the reality is it is failing to warm as predicted, everything else is a distraction from that basic fact.
The people who understand that global warming is for real, human caused, and important, are not glad about it at all. You have that totally wrong.
A slowdown in warming is what we are after. That involves keeping the Carbon in the ground.
David, it is not failing to warm as predicted. It is warming as predicted. So, that is not a basic fact. It is an incorrect statement.
Being one of those who understands that global warming is for real, human caused, and important, and is not glad about it at all, I cannot help but be amazed at the ability of commenters here to believe that it we simply ignore & cover up the science & facts and maintain that it’s not true, then it will SIMPLY GO AWAY.
This is an interesting mental disorder that surely warrants its own field of study… Greg, have you assembled a post of two on this topic before? Which structure(s) in the brain breaks down & misfires in these cases? Is it caused by neuronal death? Chemical exposure? Neurotransmitter malfunction? Structures failing to mature? Interconnections that mis-wire?
One would think that evolution would select against this and it would be bred out of humanity by now. After all, thinking such as “This box canyon won’t flood during this heavy rain and become a torrent!” and “That auroch bearing down on me isn’t real, so I’m in no danger of being stabbed to death!” would not be conducive to being passed on to future generations…
So why does this type of thinking persist past the age of 4 or 5 in some people? Serious question…
It has been shown that many humans are risk-takers, i.e. they are not risk averse, they are simply loss averse. You can think about the success of businesses that offer gambling.
So that fact that many people take the risk of ignoring global warming is no great surprise.
Being a risk-taker doesn’t equate to being willfully stupid, however. Even addicted gamblers won’t take a bet if they know there’s nothing in it for them to win!
Gambling addiction was mentioned earlier, and I think it’s interesting to ponder. I’m sure some people have been paid off to spread doubt about climate change and are just doing it for the money, but it seems clear that others aren’t. I don’t understand them, like I don’t understand casinos. Why would someone engage in a series of gambling transactions in full knowledge that the odds are stacked against them? I’ve been to many meetings in Reno (cheap hotel rooms) and it’s always strange and interesting to walk through the casinos on the way to my room. What are these folks smoking (besides, of course, tobacco)?
I was talking about risk, not certainty.
Perhaps this makes my point more clear:
You & your gambler friend are in a small aircraft at 8000 ft. The door is open. Neither of you have a parachute. You comment, “I’ll bet if you jumped out of this plane now, you probably wouldn’t live…”.
It’s not at all certain that your friend would die; there are documented cases of skydivers surviving such events.
Your friend is, as you describe, a “risk taker”. He could jump and gamble that he’ll survive the consequences.
Should your friend jump, and prove your point that he’s simply “not risk averse”? What’s in it for him to “take the risk”?
Perhaps this will make it clearer. I was talking about risk as in what people often take, say 10% risk of undesirable outcome, not near certainty of death. I’m just repeating the results of research. If you have trouble understanding the point then just ignore it. I don’t really care if you don’t understand.
David Hansen #50 –
Why not mention that the 80s were warmer than the 70s, that the 90s were warmer than the 80s, that the 00s were warmer than the 90s, that the four warmest years on record have been 2014, 2010, 2005, and 1998, and that 14 of the 15 warmest years have occurred since 2000.
That warming has not occurred as expected is not supported by the data, or rather it’s only supported by the data if you’re loony enough to believe that the data have been fudged in the interest of a worldwide conspiracy.
And then there are so many other inconvenient facts:
“It has — quite rightly — been pointed out that surface air temperature (SAT) isn’t all there is to global climate or global warming. Since 1998 we’ve witness[ed] sizeable warming of the oceans, including the deep ocean. We’ve seen a staggering decline of Arctic sea ice and the continued dwindling of most of the world’s glaciers. Sea level has continued to rise at a rate much faster than the 20th-century average (which itself was much higher than the average over the last several thousand years). It has been emphasized that a lack of “statistically significant” warming is not the same as a lack of warming. It has also been pointed out that the “pause” in SAT is not inconsistent with climate model simulations, that in fact climate models show episodes like we’ve observed “since 1998?? even in a still-warming world. And it has been shown (as climate scientists knew all along) that greenhouse gases aren’t the only factor influencing temperature, that “since 1998?? we’ve seen the most prominent known non-greenhouse factors (el Nino southern oscillation, volcanic aerosols, and solar variations) conspire to lower global temperature. It’s obvious to those whose eyes are open that without continued greenhouse-gas warming to offset these natural factors, we would have seen a notable decline in global temperature “since 1998.”
But, let’s put all those perfectly valid considerations aside…
Let’s use temperature data starting in 1979 (so we can include satellite data for the lower troposphere) and ending with 1997 to predict what we would have expected over the next 16 years, then compare that to what happened.”
The conclusion:
“Given how fast global temperature was rising prior to 1998, the real surprise which followed is not that temperatures slowed or stopped their increase … the real surprise is that temperatures rose so far so fast and were so damn hot. Even allowing for the existing trend.”
My own conclusion is that you’re a typical parroter of septic talking points, not very knowledgeable about climate science, reality, and recent research, and not very interested either.
Brainstorms, re your comment at 53.
I think it’s partly wishful thinking. “I don’t want this to be true because the consequences for me would be bad, so it isn’t.” It persists because sometimes ignoring a problem in the hopes that it will go away works.
Sometimes.
It’s also sometimes arrogance, stubbornness and people not wanting to be wrong. Former South African President Thabo Mbeki is a case study in that. He was an AIDS denialist and refused to acknowledge that Zimbabwean President Robert Mugabe had become a despot who was ruining his country.
What is the probability that Equilibrium Sensitivity will be 3.5 or greater?
Work that out and then find the orange line that includes the aerosols on this graph:
http://www.scientificamerican.com/sciam/assets/Image/articles/earth-will-cross-the-climate-danger-threshold-by-2036_large.jpg
That is the optimistic outcome for that probability. A bit complex to think about. But I think if you work out the likely probability of LTES at 3.5 or above, it might be a bit shocking. I’m not sure what it is right now (haven’t looked lately) but it is not a few percent. It is in the two digits range. Way more than you would accept for any loss of life or limb level risk in day to day life (like the change of crossing a particular street with your eyes covered with a blind fold at night in the fog)