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Ice Sheets Behaving Badly

By January 3, 2013August 6th, 2013Sea Level Rise, Uncategorized
The most recent discoveries in climate science bear little resemblance to what we hear in the media. Greenland’s melt in 2012 for example has been widely advertised in the media as just another weather event, similar to many in the past. The adage that we cannot tell for sure if any single weather event was caused by climate change is simply no longer supported in the academic literature. Our climate has changed. The vast majority of climate scientists around the world agree. Their research now tells us these amazing weather events we have been enduring are indeed caused significantly or enhanced significantly by climate change. This article is about sea level rise and the latest scientific findings that tell us that our ice sheets are losing ice far faster than previously understood, and sea level rise in the very near future will be far, far greater than previously understood.

Before I tell you once again that it is getting worse faster than the ice scientists anticipated, let me remind you that the solutions to climate change will be no more difficult than providing our planet with clean drinking water every year. I will get to number 1 immediately and number 2 at the end.

The latest from the Greenland ice sheet published in Nature Geoscience by researchers at the University of Wisconsin (Carlson and Winsor) on August 26, 2012 tells us:

The almost immediate reaction of land-based ice margins to past small increases in summertime [warmth] implies that the Greenland Ice Sheet could be poised to respond to continuing climate change. Furthermore, the prehistoric precedent of marine-based ice sheets undergoing abrupt collapses raises the potential for a less predictable response of the marine-based West Antarctic Ice Sheet to future climate change.” The paper continues; “Northern Hemisphere ice sheets were originally viewed as slow-responding parts of the climate system, but there is growing evidence that ice sheets may have responded faster [in the past] than previously thought.

Greenland Ice Loss You Tube: University of Leeds and the European Space Agency

More research from Carlson and a team of five that includes the Universities of British Columbia, New Hampshire and NASA tells us that the big ice sheet over Canada (Laurentide Ice Sheet), between 8,500 and 9,000 years ago, achieved an ice loss equal to sea level rise of 3.25 to 4.25 feet per century for centuries in a row with the same warming that we see across high latitudes today. But this is only the sea level contribution from that “Laurentide” piece of ice over Canada.

Research from the National Autonomous University of Mexico and the Leibniz Institute of Marine Science in Germany tells us of much more abrupt jump in sea level in the past. During the short warm period before our last 100,000 year-long ice age very similar to what we are experiencing today, marine archeologists tell us a reef called Excaret was suddenly drowned. This reef was in a stable area of the Yucatan Peninsula not affected by subsidence or geologic uplift processes. Corals are very picky about the depth of water that they grow in and the Elkhorn coral in particular was devastated by a sea level jump of 12 feet about 121,000 years ago. This time frame matches fairly well with the most recent collapse known of the West Antarctic Ice sheet from research by the British Antarctic Survey in 2010.

The authors are very cautious about suggesting a time period for this jump and only speak of a sudden ecological demise in the paper. I was able to coax a 100 year time frame out of the author but I sensed his great caution in identifying timelines our communications. Science is like this. Unless scientists can stand on his or her theories without even the slightest question, their statements will be conservatively thought out. The old adage of publish or perish is true. If a scientist’s work is found to be faulty, the academic publishers will think twice about publishing that scientist’s work again.

In the supplemental materials to the Excaret reef research I found more clues. It says that the jump took place in one to two generations of Elkhorn coral. The Animal Diversity Web at the University of Michigan says that the fast growing Elkhorn corals reach their maximum size at 12 years. I could not find a definition of the expected life span of an Elkhorn coral; you can make your own estimates. The next collapse of the West Antarctic ice sheet, that could happen any time now, would likely be ecologically devastating to far more than just corals. And by-the-way, cryologists call this type of collapse dynamical ice sheet disintegration. Those that have happened in the past were due to natural changes in climate of course, that were far smaller than mankind’s influence today.

Worldwide, 233 million people live within 10 feet of sea level. In the United States, 9 million people live within 10 feet of sea level. But it is not just the people who live there. Industry and agriculture are deeply rooted to our coastlines because of water transportation. The costs of adaptation and or migration of industry will far, far outweigh the costs of human displacement. And, ten feet of rise is only the beginning.

One of the most horrible things about sea level rise and climate change is its irreversible nature. Stopping global warming will not stop sea level rise and this has nothing to do with warming in the pipeline. It’s about the simple physics of freezing or melting.

It takes two-hundred and eighty-nine (289) times more heat to change the temperature of ice at 32 degrees to water at 33 degrees than it does to change the temperature of ice at 31 degrees to ice at 32 degrees. Since our ice sheets are already beginning to melt, we have obviously already added this “extra” heat to them, or at least to their surfaces. We have actually been adding this extra heat to the ice sheets since we have been emitting extra greenhouse gasses and causing extra warming in our atmosphere. More warming is happening now of course because our emissions. Since just 1988 have increased emissions over 50 percent and the total of greenhouse gases emitted since 1988 is 82 percent of all greenhouse gases ever emitted before 1988.

In November, 47 of the world’s ice scientists involved with measurement of polar ice (all of them basically) published a paper in the journal Sciencethat leaves little to the imagination. In the past, four methods of measuring polar ice change have resulted in conflict over how much ice we were actually losing. Some (outside of these scientists) even took a small bit of the data from East Antarctica and made headlines declaring that climate change had ended because of ice gains at the highest elevations (above 10,000 feet) on the East Antarctic and Greenland Ice Sheets.

The images on the right are from this research. Bear with me, I know this kind of climate science art is burdensome for some, but it’s important. The graphs are read from left to right on a timeline. On the left is the beginning of the this data in the early 1990s. On the right is the latest data, in this case it ends in 2011 (science is slow). The amount of ice loss is read from top to bottom, the lower on the graph the greater the loss. The different colors are each different satellite technologies and the shading is the possible error in each of the data sets. The whole point of this paper is that, when you look at all  the data at the same time, it all says basically the same thing. East Antarctica is gaining a bit of ice, the Antarctic Peninsula is losing slightly and the bottom has fallen out of West Antarctica and especially Greenland. A gigaton of ice is one billion tons or 2 trillion pounds of ice or 240 billion gallons of water or three thousand Empire State buildings. One millimeter of sea level rise is about 360 gigatons of ice. Click on the images for a larger view. I review research that deals with Greenland back to mid 1700s in a discussion from August 8 here.

The introduction to this research tells us: “We find that there is good agreement between different satellite methods—especially in Greenland and West Antarctica—and that combining satellite data sets leads to greater certainty.”

The techniques are satellite elevation measurement using laser and radar, electromagnetic detection and gravity detection. This is a really big deal. Very few papers of this sort have this many authors.

James Hansen, Director of NASA’s Goddard Institute for Space Studies at Columbia University since 1982, has taken a particular interest in this work. Goddard is the lead U.S. agency when it comes to climate modeling. You may also remember that Hansen was the one who broke the story of the Bush Administration’s censoring of climate science. He is still at Goddard; still their director.

The reason for Hansen’s interest in this data is of course its implications for the future and his concerns are evident in a recent open communication thatlikely foreshadows his next paper (that he says is forthcoming in early 2013). The communication title is “Update of Greenland Ice Sheet Mass Loss—Exponential?” (Exponential: like a population explosion.) In the image below titled “Greenland Ice Loss” he has taken the data from Shepherd’s team and added some doubling lines. What these doubling lines represent is the rate of ice loss if it doubles in 5 years, or in 10 years.

Right now, Hansen tells us that the current rate of sea level rise from Greenland ice loss is about 1 mm per year (equal to 360 gigatons of ice loss). You can see in Hansen’s graphic that this 360 gigatons of ice loss is the average, based on the linear rate represented by the black dashed line. However, the last data point shown on the blue line of composite data from Shepherd’s team’s research is about 500 gigatons per year and this does not reflect the big melt in 2012 that was the largest we have record of since the end of the Little Ice Age (back to the mid-1700s). This flies in the face of popular reporting that last year’s Greenland melt was a cyclical 100-year(ish) occurrence. I covered this deeply in that August 8 discussion here.

Popular reporting is often poor at best. Moving beyond the thought that any one individual weather event cannot be shown to be caused by climate change will take a while. We have been warned for decades that this would happen and that this is just the beginning. Many if not most of the climate catastrophes back to at least the turnoff the century have indeed been caused by or significantly enhanced by climate change. This is not true just because climate scientists have been warning us for decades that these things would happen on a warmer planet. A growing body of scientific evidence—as slow as the scientific process is—is beginning to show that this is the case. Knowledge inertia is strong, especially in the media where a trick once learned is hard to forget.

So the bottom is now dropping out of Greenland Melt. Hansen’s recent communication title hints at this “exponential” relationship. These “population explosion type” event starts out slow, but when it gets going good, lookout. The classic cartoon snowball running out of control downhill is another good example. Also note, they start out slow in Human time frames. In geologic time frames, of which climate is something similar, this is an abrupt event; the beginning of an abrupt climate change.

Hansen tells us that the 5-year doubling trend—meaning that Greenland’s melt will double every five years–will lead to three feet of sea level rise by 2045, and due to the explosive rate this doubling would increase enormously into a 16-foot jump by 2057. This is from Greenland alone and does not include similar melt from Antarctica and other permanent ice in mountain glaciers and ice caps across the globe. Nor does it include “dynamical ice sheet disintegration” (mentioned earlier) from a collapse of the West Antarctic Ice Sheet, similar to the one that happened (likely) 120,000 to 121,000 years ago.

When I did the research for my film  The Ice and the Seain 2007, this societally catastrophic sea level rise was only just beginning to be understood as our future reality. But there was a fair amount of fuzziness around the dates. Five years of research has gone by since. In climate science land, where climate change research could certainly be happening with greater speed and volume than anything ever before, a lifetime worth of new knowledge has accumulated. Things are happening really fast and the “perceived” debate greatly clouds the discussion with unwarranted uncertainty.

Now a word or two about evidence of dynamical ice sheet collapse in the Northern Hemisphere, then you can collapse from mental anguish and I will revive you with my discussion of the “One Percent Solution.”

In the late 1980s, a researcher named Heinrich discovered something that verified beyond doubt that the North American Ice Sheet (Laurentide) had experienced collapse events. It is almost certain that these events triggered abrupt climate change thresholds. These abrupt changes were on the order of 9 to 14 degrees or more Fahrenheit on average across the planet and 18 to 27 degrees or more across northern latitudes. It is unclear whether or not conditions exist today that could do the same because in the past, these abrupt flips of our climate system happened during the depths of an ice age when the average global temperature was more than 30 degrees (F(F) colder than it is today.

These events are called Heinrich Events and they were discovered in ocean drilling cores. There were six of them that happened in the last 100,000 years or so and they are marked in the sediment by layers containing sand and gravel that could not have possibly been deposited by slow moving ocean currents. These layers average 6 inches thick across a wide swath of the North Atlantic (hundreds of miles) that extends from Labrador nearly to the British Isles. The percent of sand and gravel that could not possibly be transported by oceans currents in these sediment layers is amazingly high at 70 to over 90 percent.

The layers were created when vast iceberg armadas melted in the North Atlantic after being released when the ice sheet periodically collapsed. The events began very suddenly but resolution in sediments only goes down to the decade level so it is hard to tell how suddenly. It could be that these collapse events began faster than a decade, we just don’t know yet. We do know that they continued for hundreds of years. The collapses certainly involved a marine ice sheet’s tendency to build and retreat. This behavior was likely common in relatively rapid geologic timescales because of the simple tendency of an ice sheet to grow taller from continued snowfall, and then spread out because of its great weight.

The North American ice sheet was centered over east central Canada and like Greenland and Antarctica ice was over two miles thick. Geologists can tell us this because they know how a great weight can depress the earth’s mantle and they know how fast it rebounds when the weight is removed. The East Coast of the U.S. is actually still rebounding from our latest ice age that ended about 10,000 years ago.

As the ice sheet grows it spreads out like slow-motion cold syrup poured on a plate. When it reaches water it floats and pushes out into the ocean. But ice is only so strong and even a mile thick floating ice sheet has its limits. When these limits are reached, the ice sheet breaks apart. We saw a little-bitty example of this happening in Antarctica in 2002.

In 35 days a Rhode Island sized piece of the Larsen B Ice Shelf disintegrated, breaking up into hundreds of thousands or millions of icebergs, bergy bits and growlers. (Bergy bits are actually a technical name for chunks of ice that are bigger than an 18-wheeler and smaller than a high school football stadium, a growler is smaller than an 18-wheeler). The way the Larsen collapsed is what is important here as it was a marine ice sheet. There is only one significant marine ice sheet left in the world that could create an event as significant as a Heinrich event and that is the West Antarctic Ice Sheet. It is about the size of Greenland (or Mexico) and it is the last of its kind because all of the rest have disappeared as our planet warmed in the last 10,000 years since the last ice age ended.

The West Antarctic Ice Sheet is grounded several thousand feet below sea level and sticks up above water thousands of feet more and this is what makes it a “marine ice sheet.” Because it partially floats, it is less stable than an ice sheet that is grounded above sea level. More importantly, the base of the ice sheet gets deeper farther inland. This means greater floating forces exist inland increasing the risk of collapse once the outer edges recede. This recession is happening now as warming ocean current melt this last remnant of the previous ice age from below as has been discovered by researchers at the British Antarctic Survey.

There is a great risk of course from collapse of the West Antarctic Ice Sheet. It could send 16 to 20 feet of sea level rise across the planet. Until recently it was understood that this collapse would take millennia, but like I said a few paragraphs back; a lot of climate science has happened recently. This new knowledge tells us that the collapse time for the West Antarctic Ice Sheet has shrunk from millennia to several hundred years for a great amount of the ice sheet to collapse, then the rest goes over a millennia or so.

In April 2012, researchers from the British Antarctic Survey and NASA changed this knowledge forever. The telling is told in the closing sentence to the summary of this research: “Climate forcing through changing winds influences Antarctic ice-sheet mass balance, and hence global sea level, on annual to decadal timescales.” The quantity of sea level rise is still in question over near-term time frames, but the thousand-year disintegration threshold for the West Antarctic Ice Sheet and even the several hundred year time frame is now unquestionably shorter.

Things change as time flies. We learn more—climate scientists have known for decades that it would be really crazy if we didn’t do anything about greenhouse gas emissions. So, we didn’t do anything about it and guess what? … The climate change world that most of us are still getting to know is no longer valid. That was the Kyoto Protocol world where limiting greenhouse gas emissions by 70 to 90 percent was what would be required to keep climate change below the dangerous 2 degrees C level (3.6 degrees F).

Now, the discussion has shifted from dangerous climate change being 2 degrees C to dangerous climate change now being 1 degree C. Researchers from the Tyndall Center for Climate Change (UK’s national climate research institute at the University of Manchester) and the University of East Anglia tell us that 2 degrees C is now “Extremely Dangerous Climate Change.” Our climate is literally changing ten times faster than climate scientists understood it would change in the Kyoto days—so says Dr. Konrad Steffen, one of the longest lived Greenland Ice Scientists and Director of the Cooperative Institute for Research in Environmental Sciences (CIRES), a joint institute of the National Oceanic and Atmospheric Administration (NOAA) and the University of Colorado at Boulder. Dr. Steffen told me this when I interviewed him at the Hvide Faulk Hotel in Ilulissat Greenland during my filming trip to make my documentary there. He was waiting for the weather to clear so a helicopter could take him up on the ice to his research station. I was bumming about with my cameras and backpack.

Today we need to do more to address climate change than we assumed needed done in the past (obviously), maybe even ten times more. This will mean more than just reducing emissions. We must begin to remove some of the climate pollution from our atmosphere that is already there. It stays there once emitted for centuries remember. Much more than half of all the greenhouse gases ever emitted remain in our sky.

This is all really bad news right? W’eeeell, me myself—personally I don’t see it as either bad or good. To me it is all actually quite fascinating. This is the way that our society evolved and now we need to do something about it. We can no longer live without fossil fuels than we can live without clean water and it is beginning to become obvious that we cannot reduce our emissions so we better start working on removing some of these greenhouse gasses from our atmosphere.

This climate change thing is only pollution you see. It is bad only if we don’t do anything about it. We have addressed big pollution issues many times in our society. The negative aspects of pollution can certainly be fixed-up so that we do no harm. An excellent example is that globally, we have been treating really bad pollution since the toilet was invented. And if you have never thought about it much and think I may exaggerate, visit a sewer treatment plant sometimes. The quantity and the immitigable noxiousness of human sewage is really, really—REALLY—tremendous. It is only through a huge investment in infrastructure across the planet for over 100 years that we have been able to tame our human toilet pollution problem so that “we do no harm.”

The One Percent Solution:

Authoritative voices tell us climate change is not real, that it is a scientific conspiracy, that it is a natural cycle soon to end and that it will be good for society. These “authoritative voices” are highlighted in a growing body of research that has identified them as being biased. They are information sources such as the Fox News Network, the Heartland Institute, the Competitive Enterprise Institute, the George C. Marshall Institute and Conservative politics in general. These same confused voices, that are telling us all of these things at the same time, are the voices that tell us that the solutions to climate change will ruin our economies… The vast majority of credentialed climate specialists say nothing of the sort.

Richard Alley, Evan Pugh Professor of Geosciences at Penn State University, one of the lead authors of the 2001 and 2007 IPCC Reports, member of the United States National Academy of Sciences and one of the pivotal international researchers in climate science, tells us in his book Earth: the Operators’ Manual, that the solutions to fixing climate pollution will cost no more than things our society has been doing for a very long time. The solutions, 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 one percent of global GDP–this $540 billion a year–is that it is little different from what we have spent on our efforts to provide safe drinking water across the planet every year for the last 100 years.

That’s right. We have spent about a half trillion dollars a year, every year for over a hundred years controlling human toilet pollution. We did this because, towards the end of the 18th century we began to see that human toilet pollution dumped in the ditch every morning was polluting our water supplies and creating ideal conditions for things like cholera, typhoid and hepatitis (to name a few). The World Health Organization tells us that diarrhea due to polluted drinking water today still causes 1.8 million deaths every year. Imagine what it would be like without toilets!

It took generations, but wastewater treatment and drinking water protection began to be accepted towards the beginning of the 20th century, somewhat like the acceptance of climate change science today has taken nearly fifty years so far (and we still have not really begun to treat climate pollution).

The cost of treating climate pollution will be little different from what we spend on the US military every year not counting wars, or what we spend on advertising every year across the planet. It is little different than the normal economic costs to our nation every year because of normal inclement weather including rain, snow, heat cold, wind, flooding and drought. It is four times less than what we spend on health care every year in the United States alone, based on the annual 2000 to 2009 average that does not include Obamacare. And remember, this is using existing technologies. New technologies will significantly reduce or even change these costs into profits.

Cleaning up climate pollution across the planet (and forgive me for repeating this), in ways that we area already doing today, will cost far less than what we spend on health care every year—just in the U.S. alone. The “voices” of vested interests are very powerful. Their money has created doubt that threatens the existence of life on this planet. Yes–threatens the existence of life on this planet. This was a far-fetched statement in the Kyoto Era, but this is not the Kyoto Era any longer.

The voices—those vested interests—did not do this to us (themselves) purposefully; they did it because of ignorance, innocence, and the pressures of their respective industries’ economics. Their billions, and their quest for billions more has allowed them to ignore, for whatever reasons, the dire warnings.

There are always a few scientists that disagree. The number of those who have placed confidence in these few scientists are now dwindling rapidly. In Texas even, the latest UT Energy Poll gives an astonishing result. Since March of 2012 the number of people believing that our climate is changing has increased from 57 to 71 percent.

In the last several years research has shown that 97 to 98 percent of actively publishing climate scientists support the consensus position. Should we trust the few that represent “the voices” or the many?

Please help get things moving by telling your friends and corresponding with your leaders. The only way we can finally overcome the voices of the few is through concerted effort that is uncommon in today’s society. It’s now up to you.


[Bruce Melton is a professional engineer, environmental researcher, filmmaker, and author in Austin, Texas. Information on Melton’s new book, “Climate Discovery Chronicles” can be found along with more climate change writing, climate science outreach, and critical environmental issue documentary films on his at Please support Bruce’s efforts by purchasing books for friends, or T-shirts and messaging gifts at his messaging website: Copyright, (including images) Bruce Melton 2013 except where referenced otherwise.]



Carlson and Winsor, Northern Hemisphere ice-sheet response to past climate warming, Nature Goescience, August 2012.

Marine Ice Sheet Collapse:

Final Laurentide Ice Sheet collapse (Canada) … Carlson et al., Surface-melt driven Laurentide Ice Sheet retreat during the early Holocene, Geophycsical Research Letters, December 2009.

Sea level rise of over 10 feet in 100 years… Blanchon, et al., Rapid sea level rise and reef back stepping at the close of the last interglacial highstand, Nature, April 2009.

289 times… The specific heat of ice and water are 2.090 kJ/kg-K and 4.1813 kJ/kg-K, respectively (or 1.16 kJ/kg-F and 2.32 kJ/kg-F in mixed units adequate for this discussion).  The latent heat of melting ice is 334 kJ/kg.  Thus the heat to raise the temperature ice from 31 to 31 F is 1.16/kg, the heat to melt the ice and raise the temperature of the water from 32 to 33 F is (334 + 2.32) or 336 kJ/kg.  The resulting ratio is 336/1.16 or 289.

Elkhorn Coral: University Of Michigan Animal Diversity Web – Elkhorn coral reaches its maximum size in 10 to 12 years. 122012)

Antarctic Collapse 120,000 years ago, British Antarctic SurveyBarnes, et. al.,  Faunal evidence for a late quaternary trans-Antarctic seaway, Global Change Biology, February 2010

233 million climate change refugees from 10 feet of sea level rise… Risk of Rising Sea Level to Population and Land Area, EOS, Transactions of the American Geophysical Union, February 2007.

Ice Loss from all available methods… Shepherd et al., A reconciled Estimate of Ice-Sheet Mass Balance, Science, November 30, 2012.
Press Release:

Heinrich Events… Hemming, Heinrich Events: Massive Late Pleistocene Detritus Layers of the North Atlantic and their global climate imprint, Review of Geophysics, March 2004.

West Antarctic Ice Sheet… Pollard and DecOnto, Modelling West Antarctic ice sheet growth and collapse through the past five million years, Nature, March 2009.

Antarctic Ice Sheet influences sea level on an annual to decadal time scale… Pritchard et al., Antarctic ice-sheet loss driven by basal melting of ice shelves, Nature, April 2012.
Press Release:

UT Energy Poll… UT Energy Poll, October 16, 2012 (accessed December 27, 2012).

Extremely Dangerous Climate Change is now 2 degrees C, Dangerous climate change is now just one degree C… Anderson and Bows, Beyond dangerous climate change: Emission scenarios for a new world, Philosophical Transactions of the Royal Society, January 13, 2011.

The One Percent Solution:

1) The message of the voices is powerful – The bias of Fox News and Conservative politics
The Bias of Fox News: Krosnick and MacInnis, Frequent Viewers of Fox News are Less Likely to Accept Scientists’ Views on Global Warming, NSF grant, Stanford, 2010.
Feldman et al., Climate on Cable, Nature and Impact of Global Warming Coverage on Fox News, CNN and MSNBC, International Journal of Press/Politics, XX, 2011.
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.
Pew Center, Political Typology: Pew Center, Beyond Red vs. Blue, Political Typology, May 4, 2011.
Brookings Institute, Fall 2011, National Survey of American Public Opinion on Climate Change, Issues in Governance, Feb 2012.

Cooper, Media Literacy as a Key Strategy Toward Improving Public Acceptance of Climate Change Science, Bioscience, March 2011.

2) The solutions to climate pollution will coast one percent of global GDP per year
Alley, Earth: The Operators’ Manual, WW Norton, 2011.

3) We spend $500 billion every year on safe drinking water… ibid.

4) World Health Organization 1.8 million deaths per year because of diarrhea caused by polluted drinking water… on 01022012.

5) Annual US military Budget has averaged $500 billion since about 1980 …

6) Advertising at $500 billion per year globally … $495 billion in 2011. Forecast to $629 by 2015. Asia is expected to overtake North America as the worldwide leader in advertising dollars spent each year at some time in the next five years. This is from eMarketer Digital Intelligence.

7) Agriculture damages from normal weather at $500 billion per year in the US alone … In the US alone we see $485 billion normal weather damages to agriculture every year.
Lazo et al., US economic sensitivity to weather events, American Meteorological Society, June 2011.
Press Release:

8) Average US health care costs from 2000 to 2009

9) In 2010, 97 to 98 percent of actively publishing climate scientists agree on the consensus position
Oreskes, “The scientific consensus on climate change,” Science, December 2004.
Anderegg, et. al., Expert Credibility in climate change, PNAS, April 2010.
Doran and Zimmerman, Examining the Scientific Consensus, American Geophysical Union EOS, January 2009.
Farnsworth and Lichter, The Structure of Scientific Opinion on Climate Change, International Journal of Public Opinion Research, October 2011.
Lichter, Climate Scientists Agree on Warming, Disagree on Dangers, and Don’t Trust the Media’s Coverage of Climate Change, George Mason University, STATS, 2008.
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.–Perspectives_of_Climate_Scientists_Concerning_Climate_Science_&_Climate_Change_.pdf