Warming Over Land will be Twice the Global Average Because of Cool Ocean Water
(Posted on the Ragblog August 9, 2012 http://theragblog.blogspot.com/2012/08/bruce-melton-biggest-misunderstanding.html)
Why didn’t they tell us this to start with for goodness sakes! An average considers warming over land and water. Warming over land is much greater than it is over water. Anyone who has ever been to the beach on a scalding summer day can tell you that. Earth is 70 percent water, and warming over land is more than twice that over water. The popular understanding that Earth will warm 2 to 3 degrees C (3.6 to 5.4 degrees F ) this century is the average warming. What us land–based humans can expect is twice or more what we have come to know global warming will be.
Why is this astounding reality virtually unknown? Why does the projected global average warming carry all the headlines instead of the actual global warming that will impact us? Why is this simple relationship, so profoundly important to us humans who live on land, almost completely absent in the news we hear about global warming?
The answer is complex, but I will try and give you a few clues. Straightforward; it’s about understanding how an “average” works. The message has always included the thought that “warming will be greater over land,” but because of other things, this part of the message gets discounted.
Those other things include “the messages” from both environmental advocates as well as those that would have us believe otherwise. It has to do with the psychology of global warming. The answer is not what we have been told would happen for twenty years. But there is more to the story than just a math problem related to how an average works.
The answer is based on our long-term assumption that we will do what we can to reduce global warming to levels that are not dangerous. For two decades we have been planning on reducing emission. We have been talking about it for so long it is like we have actually done something about it. But because we did not begin to reduce emission like was suggested prudent twenty years ago, we are no longer concerned about the middle of the road scenario (the A1B scenario) that the last twenty years of discussion has been based upon. If one ignores a problem, it usually gets worse, and now it has.
Before I get to the details, two things are important to note and I carry these with me everywhere I go. The good news first: Climate change will be no more difficult to fix than human toilet pollution. The solutions to cleaning up climate pollution, using existing technologies, will cost about one percent of global gross domestic product (GDP) per year for 100 years. The astonishing thing to understand about this 1 percent of global GDP–this massive sounding $540 billion a year–is that it is little different from what we have spent on our efforts to control human toilet pollution and provide safe drinking water across the planet every year for the last 100 years. It is little different from what we spend on the U.S. military every year not counting wars, or what we spend on adverting every year across the planet.
It is little different than the normal economic costs to our nation every year because of normal inclement weather—rain, snow, heat cold, wind, flooding and drought. It is four times less than the average 2001 to 2010 annual health care expenditures in the United States alone. New technologies will significantly reduce or even change these costs into profits.
So if the solution is so simple, why are we in this pickle? The “voices” of vested interests are very powerful. Their money has created the message that allows doubt. This greatly decreases the importance of the message of the vast majority of climate scientists. This statement however, is not as sinister as it sounds. These interests did not do this to purposefully destroy the climate that our society evolved with. They did it because of ignorance, innocence, and the pressures of their respective industry’s economics. They did it because the projected global warming was no more warming than we see every morning before 10 am. They did it because climate scientists did not convey enough emphasis on “only a small amount of change can make a big difference” and “warming will be greater over land.”
Now the bad news. Climate change is much worse than we as a society recognize. Why is it worse, and why can’t we recognize it? American’s views on climate change are 20 years behind those of the vast majority of climate scientists’. Only 60 to 70 percent of climate scientists believed that Earth was warming in 1991, compared to 97 to 98 percent today, but only 60 to 70 percent of the public believes in climate change today. This is one challenge that we face: to convince those unconvinced so that we can work together towards the solutions.
Why do we not understand current climate science and how does this make it worse? We live in a Kyoto world. This is a world that is ruled (in our minds) by the philosophy of the Kyoto Protocol. Kyoto said that if we started reducing emissions slowly, over time our climate would change little. We would keep total warming beneath that critical 2 degrees C threshold that marks the imaginary line between dangerous climate change and not-dangerous climate change.
Climate change is a big deal, but on a whole we think it is not nearly so big a deal as it is. Our expectations are low. It has to do with that thing I mentioned about our everyday temperature changing a couple of degrees every morning before 10 am. But it also has to do with what we hear in the media every day. We as a society have talked incessantly about the reality of climate change; about greenhouse gases, emissions reductions, Cap and Trade and dirty coal. We have dwelled endlessly on one or two little mistakes in the massive Intergovernmental Panel on Climate Change report (IPCC), and the world was riveted by the theft of personal emails and statements taken out of context that resulted in four separate independent international investigations (all of which exonerated the accused btw).
Now that we see climate change happening with the increase in extreme weather, the “innocent interests” are telling us that it is only a natural cycle, a global scientific conspiracy, or the good one: that warming has stopped. These claims are indeed backed up by a few climate scientists. So there is skepticism among even the willing. But these things are not based on what the vast majority of climate scientists are telling us. The “doubt” has allowed only 60 to 70 percent of us to trust what 97 to 98 percent of climate scientists are telling us. Because there is doubt, because there is a public perception that climate scientists still do not know, we assign a smaller risk to the warming. If we understood the risks as the vast majority of climate scientists do, our perception of the size of the problem would be much greater (as theirs already is).
The plain truth however is that we did not do what we were supposed to do 20 years (or more) ago. We have not reduced emissions to 1987 levels by 2012 as was required under Kyoto and in fact, since 1987, across the globe we have emitted nearly as many greenhouse gases (87 percent) as have been emitted from 1987 back to the mid-1700s. Earth’s population has increased 40 percent since 1987 and 1,000 percent since 1750. Before 1750 hardly counts. And just for the record, the United States was among only two other countries in the world: Afghanistan and South Sudan that did not ratify the Kyoto Protocol.
Responsibility for this mess can also be found in the George W. Bush Administration. Three weeks after his inauguration, he reneged on his promise to enact Cap and Trade legislation and avowed to never ratify the Kyoto Protocol. This act gave American’s “permission” to doubt. Bill Clinton is also to blame. He had the opportunity to ratify Kyoto as well, but stayed silent on the issue because of “political pressure” from those vested interests that keep popping up in this discussion.
As a consequence of our collective D & D (denial and delay) and the greatly increased greenhouse gas concentration in our sky since the Kyoto message was created, our climate is changing much faster and with much greater impacts than we have understood it would for the last 20 years.
The delay is important. It’s another one of those “buried messages” from the climate scientists. They have been telling us for twenty years that it takes decades to generations for climate change to catch up with greenhouse gases. This is because of the great cooling capacity of the oceans. But this message was buried. We have been cruising along for twenty years thinking everything was fine, because our climate was not changing. It was if we were actually reducing emissions. (This delay is called the climate lag and I will get to it soon.)
Now: Remember that good news I mentioned at the beginning of this article. It is real, and it is very good news indeed. We need to remember this good news because the bad news, the title of this article, is simply astonishing. What I have to report is not that we can expect to see twice as much warming over land as the average global warming of 2 to 3 degrees C (3.6 to 5.4 degrees F ) from the Kyoto message that have come to understand over the last decade or two. We have long since passed this point.
The 2 to 3 degrees C of warming that we have come to know so well was basically what would happen by the end of the century under the A1B scenario. The A1B scenario is one of the 40 IPCC scenarios that were distributed to climate modelers in 1998 for the 2001 IPCC Third Assessment Report. Developed by 50 scientists from 18 countries, the scenarios came in four families and ranged from a perfect world to the worst-case scenario and were based on the next century, 2000 to 2100.
In the middle of the pack somewhere is the A1B Emissions Scenario. The “B” is for “balanced.” The A1B Scenario represents a balance of energy sources including fossil fuels and alternative energy. The scenarios remained the same between the 2001 and 2007 IPCC Reports, but the models changed and a lot of things that go into the models changed. Knowledge for the 2007 report had advanced six years over the 2001 report. Like in cats and dogs, that’s a long time in climate science years.
The results of the models from the 2001 and 2007 reports were quite similar. The difference was in resolution. The 2007 report could see a much smaller areas than the 2001 report. Sub-continental scale areas were now visible.
As can be seen from the image “Average Global Temperature,” the A1B scenario clearly shows that by 2090 to 2099 we will see 3.5 to 4.5 degrees C (5.3 to 8.1 degrees F) of warming over land in the U.S. This is similar to most of the land across the planet, with much less warming over water. This image comes from the 2007 IPCC Report and these model results are what average out to 2.8 degrees C of warming for the A1B scenario. This 2.8 degrees is consider the “most likely” warming in the report, and 2.8 degrees is in the 2 to 3 degrees C range commonly found in the media. The “B” and “A2” scenarios represent one of the better scenarios and one of the worse scenarios.
The A2 scenario is about the same as the worst-case scenario called A1FI. This image shows 5 to 5.5 degrees C of warming across a broad swath of the middle of North America, or just under 10 degrees F.
But it is the 2 to 3 degrees C warming of theA1B middle of the road scenario that we understand we can expect based on the ancient (in climate knowledge years) message that most of the public now understands.
After twenty years of the D & D game things are now much worse. Before I tell you that the latest average global warming projections are twice what we previously thought, and they will happen twice as fast, I need to say a few things about the supercomputer models used to create these ghastly forecasts because most folks do not trust climate models as far as the can throw a supercomputer.
The vast understanding that the public has about climate models is that they can somehow be compared with weather forecasting models. The resulting mental leap allows us to think that, like weather models, climate models cannot forecast their way out of a wet paper bag. This is another one of those things that comes from our innocence and ignorance that the D & D gang has worked so hard to make sure we mis-know.
The results generated by climate models cannot be compared to the results generated by weather models. Both are basically the same animal—the same programming in some cases. Climate modeling however, function on an entirely different level from weather modeling.
Meteorologists rely on a handful of different models to forecast the weather. Some work better than others at different times of the year or considering different things going on across the planet like the presence or absence of El Nino for instance. To create a forecast, a meteorologist (or weathercaster) first loads up all of the current weather data from across the planet or a continental region (a lot easier than it sounds because academic institutions supply this information in ready to consume packages) and then they run them into the future for a week or two. The results are, as you and I know, quite variable after 3 or 4 days (to say the least!) Weather models are much, much better than they once were and really, the forecasts are quite good out to 5 to 7 days, considering past performance.
Climate modelers do something entirely different. The do not load the models up with the current weather conditions across the planet, or across a continental region. They start with any old typical batch of weather data and run the model. Then they blindly change the weather data in the model to represent any other typical weather from that same time frame. Like on May 30th in Chicago it might be 88 degrees and sunny; another May 30th might be 67 degrees and rainy, another might be 79 degrees and partly cloudy. They make up dozens and scores of these simulations and run them all off into the future on different platforms, similar to the different models that meteorologist use. They start their climate models hundreds and even thousands of years in the past and run them hundreds and thousands of years into the future. Backing up the clock to some ancient time in the past helps confirm them as they recreate our past climate inside the computer. The time span of climate models is 25,000 times longer than the 14 day outlook.
The climate modelers than have scores of results that, like the television weatherpersons’ seven-day outlooks, are all different. Of course all of the weathercaster’s models are not different, only the last few days of each are goofy, but you get the picture.
The climate models don’t even start with the same weather so even the first five days of all the climate model results will be different. So what do the climate modelers do with all of these goofy forecasts based on imagined weather? They average them all together of course. This is what climate is. It’s the average weather. Climate does not give a great-horned hoot about the weather on any individual day. That is called weather. It’s not climate.
The climate models have been remarkably accurate and remarkably consistent for thirty years. The public conception that they are not is just another one of those D& D myths. Like all myths, it is indeed grounded in truth, but this truth is “buried” again, like so many other things, for so many other reasons.
The truth about climate models is they are very accurate for forecasting climate except when it comes to abrupt climate changes. Abrupt climate changes are not what the climate change discussion is about. We sometimes hear about irreversible tipping points and climate thresholds that can and often are associated with abrupt climate change, but in general, these things are fuzzy “climate scientist” concepts that are very poorly understood by the public.
As an example, Greenland ice cores are some of the most accurate climate archives on the planet. Over 100,000 years of gases and dust have been stored in the deep freeze in Greenland (and Antarctica too). From two mile deep ice cores drilled in the center of the Greenland Ice Sheet, we can read this 100,000 years of climate history like a road map. For the last 3 million years, it has never ever melted, enough to completely melt the last years’ worth of snow at the top of the 11,000 foot tall ice sheet that is ten times the size of Great Britain and three times the size of Texas.
These two mile long glimpses of preserved annual snows; compressed to ice; holding time capsules of air and deposited dust, and easily visible in annual layers, are one of the most amazing repositories of natural history ever found. They show us that our climate has abruptly changed 23 times in the last 100,000 years. The changes have been up to ten degrees (F) average across the globe (20 to 40 degrees in Greenland) and usually happen in a few decades to a few generations. But when our climate is being pushed the hardest, like during solar cycle changes, or feedbacks from melting ice sheets, the changes have been recorded in as little as a couple of years. All of these changes happened when Earth was within a few degrees of as warm as today, or colder. All of them happened when our CO2 concentration was about the same as or less than it was during the Industrial Revolution.
Today we are changing the CO2 concentration of our atmosphere 14,000 times faster than anytime normal in the last 610,000 years. Abrupt changes loom in our future. But climate models do not predict abrupt changes with any accuracy at all. The science is still young, but not that young. It is not young enough so that the average climate long-term changes cannot be reliably modeled. But it is immature enough to not be able to work out the abrupt changes yet. Importantly, we know these things happen, they happen geologically often, and they happen when our climate is being forced hard.
Then models then, used to project the slower changes in our climate like with the IPCC scenarios, are totally valid. Because we have such a poor understanding of what causes abrupt climate changes, these things are not included in the IPCC report. But the D & D crowd uses this inaccuracy to brand the entire modeling world as untrustworthy. Because of the public perception that weather and climate or bound at the hip, it’s an easy myth to succumb to.
Now things get complicated so pay attention. There is a lot of math and there will be a quiz. The IPCC stopped taking papers for their 2007 report in 2005. The data collection and evaluation, peer review and publishing phase for scientific papers generally takes two to four years or longer. This means that the latest climate science that the IPCC 2007 Report represents is based on climate science circa 2001 to 2003. So when these mega reports come out, they are already five years old. Today the 2007 IPCC Report is ten years old. A lot has happened in climate science land since.
The paper that I am reporting on in this article came out in September 2009. I’ve written about it several times and referenced it more. But it was just recently that I realized the enormity of these “new” projections compared to the everyday message delivered by the media. This work, out of the Oak Ridge National Laboratory, Notre Dame, and the National Center for Atmospheric Research (Ganguly 2009) tells us that because emissions are now along the path of the worst-case scenario (A1FI), we should be focusing our understanding of future (and current) changes based on this scenario, not the middle of the road A1B scenario. What the authors say in the first few sentences of the report is telling:
“Recent observations of global-average emissions show higher trajectories than the worst-case A1FI scenario reported in IPCC AR4 (2007 Report). Average A1FI temperatures trend higher than the best-case B1 as well as the relatively worse-case A2 scenario.”
AR4 is the Fourth Assessment Report of the IPCC 2007 Report. The B1 Scenario is similar to the B scenario in the image above.
For nearly 20 years now we have been expecting impacts from climate change to reflect the middle of the road path or the A1B Emissions Scenario. What we have been told was that impacts would basically be small if we kept our collective noses clean and did our emissions reductions homework. Small is anything but what they will be.
This team has looked in detail at sub continental region warming from the A1FI scenario (the worst-case scenario from 1998). In addition, they have provided graphic displays of the upper limits of the worst-case scenario. Each scenario represents different tweaks to the model, or different versions of our future. As an example, the difference between the A2 (worse case) and the A1FI scenario (worst case) is mainly in midcentury temperature. By the end of the century, both scenarios are about the same. This is because A1FI is fossil fuel intensive is (the “I” in A1FI), whereas the A2 family has a greater alternative energy mix but a higher end-of-century population.
It’s important to note that the A1FI is NOT the “end-all” worst-case scenario. The A1FI did not include the extra population of the A2 scenario. Since the scenarios were devised, we have discovered how to economically utilize vast deposits of tar sands and oil and gas shales. These “new” sources of fossil fuels push the limits of the worst-case scenario farther than is represented in the 2007 IPCC Report or the 1998 scenarios.
Seeing that our emissions are worse than the worst-case scenario, and that we are not reducing emissions but growing them rapidly, we should look at the high end of the worst-case scenario to see where our temperature is going. We need to pay particularly close attention to the high end because of our climate lag. The climate lag is the amount of time it takes our climate to adjust to greenhouse gas concentrations. It is about 30 years to see significant changes in climate and I will talk about that more shortly.
The “high end” of warming can be seen in the image “Warming Over Land.” Look at the top image labeled “Upper Bound 2050-2000.” This is how much warming we can expect to see with the worst-case scenario on top of how much warming we have already seen up to 2000 (about 0.8 degrees C or 1.4 degrees F).
Over a very large part of the U.S. we can expect to see 5 to 8 degrees C (9 to 14.4 degrees F) of warming and again, because our emissions are as bad as or worse than the worst-case scenario, we should be looking on the high side of the suggested range.
This means that 8 degrees C of warming, or 14.4 degrees F, will be the average amount of warming by 2050. And don’t forget, this is the land component of the global average. The global average warming is still 5 to 6 degrees C by 2100 for the A1FI scenario. Look how much cooler the oceans are and how vastly much more area the oceans cover. A lot of heat on a small amount of land can be averaged out with a large ocean and a small amount of warming.
This map is deceiving too. Because the earth is round and maps are flat there have been several different ways to draw a global map. This one exaggerates the areas near the poles to make everything fit into a rectangle. Antarctica for example is a little larger than half the size of North America, but on this map it looks much larger than North America. This skew greatly increases the “apparent” area of greater warming at the poles and needs to be considered to see just how substantially the oceans affect the average temperature.
The most important thing though, is that unless we truly get a handle on our emissions, and even begin to remove some of the excess CO2 loading that is already in our atmosphere (yes, removing more CO2 than we are putting in every year) we are likely locked into warming for the 2050 time frame. Why is this?
The climate lag, or climate delay, is 30 years. Because of the great heat absorbing ability of our oceans (70 percent of the earth) it takes our climate 30 years to reflect the warming of the actual greenhouse gas concentration in the sky. This is like coming home to a cold house in winter and turning on the heater. It takes time to warm up the house, just like it takes time to warm up the earth. There is a lot of cold stored in the walls and floor that has to slowly leak out into the house as it warms.
The 30 year lag is deceiving too. It takes decades to generations for our climate to react to changes in greenhouse gases in a way that is measurable. But the lag goes on and on. It takes on average 1,000 years for waters in the oceans to circulate once around the great ocean currents. This means that it will be 1,000 years before all of the cold abyssal waters have a chance to pass along the surface and start absorbing heat. It takes many cycles of the ocean to fully lose all of that cold storage, or to come into equilibrium with the atmosphere.
So the 30 year climate lag tells us that that today, we are operating on CO2 concentrations in our atmosphere from the early 1980s. Our climate is responding to greenhouse gas concentrations in our atmosphere from the way it was in 1982. In 1982 we had only emitted half of the greenhouse gases—since the Industrial Revolution—as we have emitted today. In 30 years our climate will reflect the fact that we have doubled our atmospheric load of greenhouse gases, not the emission rate, but doubled the entire load in the sky. (Annual emissions have increased 50 percent since 1990.)
That is of course unless we seriously begin to reduce emissions and start to reduce the load in the sky, during the next eight years. This is why you hear that we are “locked in” to so much warming, or that additional warming is “already in the pipeline.” The fact that we continue to rapidly increase our global emissions does not bode well. The likelihood that we can make a dent in the next eight years does not seem good at the moment. (Don’t lose hope: remember the solutions and toilet pollution, and the happy ending at the end of this article.)
The simple reality is that many of us are dangerously close to seeing more than 14 degrees F of average warming in 38 years. Heat waves are bonus degrees. In the 2011 heat wave in Texas last August it was 6 degrees above average in Austin. It is has been even hotter in the Plains and parts of the Northeast this year. Like the increasingly unprecedented weather extremes today, climate scientists tell us in the future, these extremes will be even more extreme.
From 1938 to 1998 the 30-year average August temperature in Austin was 84.5 degrees and varied no more than 0.3 degrees (F). Since, it has risen to 85.8 degrees F. In a dozen years, our average August temperature in Austin has risen four times more than the largest change seen for the last 60 years. In 2011 in Austin during August the average temperature was almost 91.6 degrees, 5.9 degrees above average.
What about the heat island effect? A small amount of this warming is certainly because of the heat island effect, but only a very small amount.
The High Plains Regional Climate Center (HPRCC) shows us last Augusts’ temperatures in vivid hues. Looking closely at the Austin and San Antonio areas it appears the urban heat island is running strong, but look at the larger metro areas of Houston and Dallas/Fort Worth. The counties where the dots are representing these metro areas are almost completely full of concrete and asphalt, yet the red blobs are not centered on those counties. Then there are all those red blobs not associated with urban areas. The urban heat island may play a role, but it is a small one.
Across all of Texas last August the average temperature was 86.8 and the average 30-year summer temperature across Texas 81.4. So for all of Texas, and in Austin, we saw 6 degrees of extra heat during last August’s’ heat wave.
In 2050, with 14 degrees of warming above 2000 (which is basically our 30-year average), the average August temperature will be 100 degrees. Compare this to the hottest average summer temperature in the Western Hemisphere of 98 degrees at Death Valley.
During heat waves, it will not just be 6 degrees warmer than average but much more, at least this is what the models say and they have been pretty much on the mark so far. So figure an average August temp of 106 to 110. The average high will be ten or fifteen degrees warmer than this or 123 to 128 degrees. (You notice I am adding everything to the high end of the range. This is because our emissions are worse than the worst-case scenario and there is so little time to make an impact with the mindset of our society today.)
One last fantastic number: heat waves have spikes in temperature. The hottest day is about 5 degrees warmer than the average heat wave high temperature. This puts us, in just 38 years when most of us are still alive, around 133 degrees (plus a little for the heat island effect) for an all-time record high. The hottest temperature ever recorded on Earth was in Libya at 136 degrees. In Death Valley it was, 134 degrees.
All of Texas will be this hot and much of the Great Plains as well.
Think of what the countryside looks like in Libya or Death Valley. Let me repeat in very plain but unimaginably alarming language: The average summertime temperature in Death Valley is 98 degrees. In Austin, in August, in just 38 years, it will be 100 degrees unless; our leaders start listening to our climate scientists. Please make it a priority to tell your elected officials that it’s the scientist way or the highway. It is within your power to unelect these “politicians.” It is our responsibility to do so unless they act fast.
This action needs to be far more than what was anticipated with Kyoto. The relatively small emissions reductions required prior to the turn of the century would have done the trick. We were supposed to have reduced our emissions to 1987 levels by this year—2012. Instead, emissions are up more than 50 percent.
This said, we must have hope. Let me repeat my latest message showing that all is by no means lost. We have the capacity within our society to do things like keeping Austin from becoming hotter than Death Valley in our lifetimes. It’s only pollution. We have conquered challenges of this magnitude before. To fix our climate across the world, spending will be no more than our annual U.S. military budget. It will be no more than the cost of clean drinking water. Let’s get the message across. It’s only pollution.
References:
American’s view on climate change are 20 years behind: For an in-depth evaluation see “The Climate Awareness Drought is Over .” http://theragblog.blogspot.com/2012/05/bruce-melton-climate-change-awareness.html
Gallup, March 30, 2012 In U.S., Global Warming Views Steady Despite Warm Winter: http://www.gallup.com/poll/153608/global-warming-views-steady-despite-warm-winter.aspx
Pew Center, Modest Rise in Number Saying There Is “Solid Evidence” of Global Warming, November 9-14, 2011 (Published December 1, 2011) :
http://www.people-press.org/files/legacy-pdf/12-1-11%20Global%20warming%20release.pdf
Yale 2012: Weather extremes caused by climate change have changed public awareness: Leiserowitz et al., Extreme-Weather-Climate-Preparedness, Yale Project on Climate Change Communication, April 2012.
http://www.climateaccess.org/sites/default/files/Leiserowitz_Extreme%20Weather%20Climate%20Preparedness.pdf
Gallup, March 30, 2012 – Americans’ Worries About Global Warming Up Slightly: http://www.gallup.com/poll/153653/americans-worries-global-warming-slightly.aspx
Public belief that climate change is happening has only recently risen above 1991 beliefs of climate scientists: Climate Scientists Agree on Warming, Disagree on Dangers, and Don’t Trust the Media’s Coverage of Climate Change, George Mason University, STATS, 2008. http://stats.org/stories/2008/global_warming_survey_apr23_08.html
Climate Change Cues: Brulle et al., Shifting public opinion on climate change. An empirical assessment of factors influencing concern over climate change in the US 2002 to 2010, Climatic Change, Feb 2012.
http://www.pages.drexel.edu/~brullerj/02-12ClimateChangeOpinion.Fulltext.pdf
97 to 98 percent of scientists:
Oreskes, “The scientific consensus on climate change,” Science, December 2004. http://www.sciencemag.org/content/306/5702/1686.full
Doran and Zimmerman, Examining the Scientific Consensus, American Geophysical Union EOS, January 2009. http://www.ucsusa.org/assets/documents/ssi/DoranEOS09.pdf
Bray and Storch, A Survey of the Perspectives of Climate Scientists Concerning Climate Science and Climate Change in 2008, Institute for Coastal Research, Geesthacht, Germany, 2010. http://ncse.com/files/pub/polls/2010–Perspectives_of_Climate_Scientists_Concerning_Climate_Science_&_Climate_Change_.pdf
Farnsworth and Lichter, The Structure of Scientific Opinion on Climate Change, International Journal of Public Opinion Research, October 2011. http://ijpor.oxfordjournals.org/content/early/2011/10/27/ijpor.edr033.short?rss=1
Anderegg et al., Expert credibility in climate change, Proceedings of the National Academy of Sciences of the United States of America, April 2010.
Climate Scientists Agree on Warming, Disagree on Dangers, and Don’t Trust the Media’s Coverage of Climate Change, George Mason University, STATS, 2008. http://stats.org/stories/2008/global_warming_survey_apr23_08.html http://www.pnas.org/content/early/2010/06/22/1003187107.full.pdf+html
Goot, Anthropogenic climate change: expert credibility and the scientific consensus, Garnaut Review Secretariat, 2011. http://hdl.handle.net/1959.14/159903
Climate Lag 30 years: It takes a third of a century for two thirds of the heat from global warming to be absorbed by the oceans, Hansen et al., Earth’s Energy Imbalance: Confirmation and Implications, Science, June 2005. http://pubs.giss.nasa.gov/docs/2005/2005_Hansen_etal_1.pdf
The A1FI scenario, The Worst-case Scenario and warming over land twice or more what we have been expecting:
Ganguly et al., Higher trends but larger uncertainty and geographic variability in 21st century temperature and heat waves, PNAS, September 2009. http://www.pnas.org/content/106/37/15555.full