Ten scientists analyzed the article and estimated its overall scientific credibility to be ‘very low’. more about the credibility rating

A majority of reviewers tagged the article as: Flawed reasoning, Inaccurate, Misleading.

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SCIENTISTS’ FEEDBACK

SUMMARY

This Breitbart article comments on a story by ThinkProgress about a study related to past climate, mistakenly concluding that it invalidates the science that shows human activities are currently altering the climate of our planet.

Scientists who reviewed the article explain that it builds on a fallacious reasoning, as if the fact that climate has changed due to natural forcing in the past would make it impossible for human emissions of CO 2 to change it now. In reality, the climate of the Earth can be influenced by various forcings, including changes in the Sun’s irradiance and atmospheric concentrations of greenhouse gases, which in turn can be due to natural causes (as has been the case in the past) or activities related to human actions—as is the case currently.

All the scientists indicated that the content of the article does not support the claim made by the headline.

In addition to Breitbart, a number of other outlets published stories repeating the mistaken claim that this scientific study would disprove the human origin of climate change, including: Climate Change Dispatch, Godfather Politics, Technocracy.

You can read the article here. (To read the scientists’ annotations in context, visit the article and install the Hypothesis browser extension.)

UPDATE (15 April 2019):

After publishing, we received a comment from an author of the study that the Breitbart article is commenting on, which is now included below. Additionally, Mark Richardson’s name was not correctly displaying above his annotation comment, causing it to appear as part of the comment above it. This error has been fixed.

GUEST COMMENTS

Matteo Willeit, Postdoctoral Researcher, Potsdam Institute for Climate Impact Research:

As the lead author of the paper published in Science Advances on which this article is based on, I would like to state that it is a misrepresentation of the findings published in Willeit et al (2019)*. Our paper does not in any way disprove the human origin of current climate change. On the contrary, our model, which is able to reproduce the last 3 million years of natural climate variability, clearly shows that the rise of atmospheric CO 2 concentration since the industrial revolution can not be explained by natural climate processes.

Willeit et al (2019) Mid-Pleistocene transition in glacial cycles explained by declining CO 2 and regolith removal, Science Advances

REVIEWERS’ OVERALL FEEDBACK

These comments are the overall assessment of scientists on the article, they are substantiated by their knowledge in the field and by the content of the analysis in the annotations on the article.

Richard Betts, Professor, Met Office Hadley Centre & University of Exeter:

Woefully ignorant.

We are certain that humans are responsible for the current rise in atmospheric CO 2 concentrations, because the amount being emitted is more than enough to explain the amount building up in the atmosphere. Climate scientists are well aware that there are also natural changes in the carbon cycle that have led to higher CO 2 concentrations in the past, and in fact this gives more of a cause for concern rather than less, because it shows that a warming climate can cause natural carbon sinks to weaken and therefore further accelerate the rise in CO 2 .

Mark Richardson, Research Assistant, UCLA/NASA JPL:

The new research shows that a past high CO 2 period had lots of global warming, just like we expect from today’s human-driven CO 2 changes. Breitbart’s argument is that since CO 2 changed naturally before, we can’t change it now. This is like saying that fires happened naturally before so there is no way any of us could cause a fire. It’s wrong.

Benjamin Horton, Professor, Earth Observatory of Singapore:

Incredibly misleading. The Pliocene is a warning of what CO 2 levels can do to the planet

Ken Caldeira, Senior Scientist, Carnegie Institution for Science:

It is hard to imagine that a well-intentioned person can so profoundly misunderstand the science. Assuming the author is acting in good faith, this article provides evidence that motivated reasoning can produce results that appear delusional to well-informed people.

By the reasoning of this article, if a rock rolled down a hill three million years ago, no human can be responsible for rolling a rock down a hill today. The fallaciousness of this reasoning is astounding.

Ted Letcher, Research Scientist, Cold Regions Research and Engineering Lab:

Without going into any greater detail, this is quite possibly the worst “climate”-related article I’ve ever encountered. The “logic” is completely nonsensical and the writing is of extremely poor quality. This article isn’t worth reading, not even for the shock value.

Lindsey Nicholson, Postdoctoral research fellow, University of Innsbruck:

This article correctly reports the conditions during a warm climate period in past geological time, but then incorrectly and unfoundedly claims that is evidence that human activities are not responsible for Earth’s current climate trajectory. In reality, human activities have been demonstrated robustly by multiple lines of evidence to be profoundly influencing modern climate.

Christopher Merchant, Professor, University of Reading and UK National Centre for Earth Observation:

The article presents us with a false choice between believing that people’s actions today affect climate and believing that the climate of Earth has changed naturally over millions of years. Both these ideas can be true—and both these ideas are true.

Michael Henehan, Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam:

This article (perhaps deliberately) cherry picks one observation (out of context from the paper) and makes up a whole story about it disproving global warming. The level of misunderstanding about this paper is so high that I cannot be convinced that it is anything other than a wilful attempt to misguide their readership.

Marcus Badger, Lecturer in Earth Sciences, The Open University:

This article completely misunderstands the point of the science it reports on.

Twila Moon, Research Scientist, University of Colorado, Boulder:

The analysis in this article is wrong, using flawed reasoning to draw incorrect conclusions.

Over thousands to millions of years, other natural processes can change the global temperature, including warming it. But the warming occurring now, over less than 100 years, is primarily caused by humans.

ANNOTATIONS

The statements quoted below are from the article; comments are from the reviewers (and are lightly edited for clarity).

Yes, you read that correctly, three million — million — years ago CO 2 levels on Earth were the same as they are today, but there is one major difference between three million years ago and today… Marcus Badger, Lecturer in Earth Sciences, The Open University: This part of the article does accurately report the findings of the paper it links to: CO 2 is now higher than it has been for 3 million years. Although not a new result (see Martinez-Boti et al 20151), the linked study by Willeit et al2 has new model simulations looking how climate changed from the Pliocene to the Pleistocene, and demonstrates how declining CO 2 levels lead to a change in the climate system. However what follows is largely a misunderstanding of the implications. 1- Martinez-Botí et al (2015) Plio-Pleistocene climate sensitivity evaluated using high-resolution CO 2 records, Nature

records, Nature 2- Willeit et al (2019) Mid-Pleistocene transition in glacial cycles explained by declining CO 2 and regolith removal, Science Advances Michael Henehan, Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: The author writes this as if this is something that is a surprise. We all know that the Earth’s CO 2 levels were higher at various times in the past. In the Eocene, 50 million years ago, they may have even been four times as high. This is not an issue. In the past, rates of volcanic CO 2 emissions globally were higher as continental spreading rates changed, for example. Saying that CO 2 isn’t rising now due to humans just because it used to be high in the past is like saying “I didn’t chop the cherry tree down because 40 years ago there was never a cherry tree there”. It is totally unrelated.

CO 2 levels were the same then as they are now Marcus Badger, Lecturer in Earth Sciences, The Open University: Yes, naturally CO 2 were as high in the Pliocene 3 million years ago as they are today. We have good records of the past 66 Million years of CO 2 -driven climate change, and these record a broad decline over that time, with the Pliocene the last time CO 2 was naturally as high as it is today following anthropogenic emissions.

We have also been told the problem is DEFINITELY NOT a billions-year-old planet running through cycles where the temperature might fluctuate a bit. Marcus Badger, Lecturer in Earth Sciences, The Open University: This confounds natural variations in CO 2 in the geological past with human-caused emissions today. Yes, CO 2 has changed naturally over time, causing changes to climate, but the high levels and rapid increase we are seeing today is because of human-caused emissions. Mark Richardson, Research Assistant, UCLA/NASA JPL: This entire article’s “proof” is just saying that “higher CO 2 happened before humans, therefore humans can’t cause higher CO 2 “. Here are logically identical arguments: “England scored goals before Harry Kane, so Harry Kane can’t score goals” Or in American English: “The New England Patriots scored touchdowns before Rob Gronkowski, so Rob Gronkowski can’t score touchdowns” Or more simply: “Fires happened before humans, so humans can’t cause fires”. So if you agree with this article’s logic and that humans aren’t causing CO 2 to rise, you also have to believe that Harry Kane and Rob Gronkowski never scored anything and could never score anything, and that no fire has been caused by a human ever. Human-caused global warming, goals by Harry Kane, touchdowns by Rob Gronkowski, and fires set by people are all in the same boat. We have enormous evidence that they exist. Michael Henehan, Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: We are well aware that there are climatic fluctuations through geological time. Huge numbers of scientists study how the Earth’s climate has fluctuated before, and we know what caused those changes. Current warming is not related to any natural climate cycle, or process, or astronomic phenomenon.

According to the study, scientists also discovered that during this period of Global Warming “there were no ice sheets covering either Greenland or West Antarctica, and much of the East Antarctic ice sheet was gone.” Marcus Badger, Lecturer in Earth Sciences, The Open University: This is where the real logical fallacy of this article becomes clear. Indeed, when CO 2 was naturally as high as we have caused it to be now, the world was much warmer than today because of the naturally higher CO 2 . It therefore follows that the high CO 2 levels we have created in the atmosphere will lead to a warmer world, just like the Pliocene.

“there were no ice sheets covering either Greenland or West Antarctica, and much of the East Antarctic ice sheet was gone.” How is this possible 2,999,971 years before Arnold Schwarzenegger bought his Hummer? Michael Henehan, Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: What this study tells us is that the last time CO 2 was as high as 410 ppm (back then through natural causes), there was no ice on Greenland or West Antarctica. What this means is that we can potentially expect (once the climate has equilibrated to its new CO 2 levels) that these ice bodies will melt in the future from anthropogenic CO 2 release. If this happens, the sea level will rise by metres, and many coastal and lowland cities will be affected. In a way I have to profess my admiration- how a news outlet could take a paper presenting evidence that we should be very worried about CO 2 being 410 ppm, and turns it into a paper that “debunks climate change”, is beyond me. It really is a feat that must have taken a lot of imagination and creative thinking.

How is this possible 2,999,971 years before Arnold Schwarzenegger bought his Hummer? Richard Betts, Professor, Met Office Hadley Centre & University of Exeter: Because the amount of CO 2 naturally present in the atmosphere depends on how much is being released or taken up by the oceans, land ecosystems, and chemical reactions involved in rock weathering. These change naturally, but gradually, over thousands or millions of years. Human emissions of CO 2 are merely adding an extra factor to the equation, but it is one which has a big effect over much short timescales (the last few decades). Michael Henehan, Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: It is possible because CO 2 sources (e.g. volcanic degassing) and CO 2 sinks (e.g. from chemical weathering of the Earth’s surface) were differently balanced back then. It is not a mystery, it is well understood science that has countless papers about it, and a serious journalist (if they profess to be one) would have made some effort to educate themselves before writing such an article.

a study that totally debunks the whole concept of man-made Global Warming Marcus Badger, Lecturer in Earth Sciences, The Open University: The study does the complete opposite of this, by showing that high levels of CO 2 has caused a warmer world in the past, it confirms what we know about how anthropogenic CO 2 emissions are and will continue to warm the planet.

running through cycles where the temperature might fluctuate a bit. Richard Betts, Professor, Met Office Hadley Centre & University of Exeter: The Earth’s climate has always varied, even before humans began to influence it. Climate scientists have always been very clear about this. But human-caused emissions of CO 2 and other greenhouse gases have now added a new cause of climate change in addition to the existing causes of natural climate variability.

How is that possible 2,999,945 years before Americans moved to the suburbs and lit up the charcoal grills? Michael Henehan, Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: Again, this is possible because at various times in the Earth’s history, sources and sinks of CO 2 into the atmosphere have had varying strengths. These are natural changes in CO 2 levels that have slowly happened for 100s of millions of years. However, modern CO 2 rise is faster than any rise ever seen in the last 66 million years* and quite possibly ever before in the geological record. Zeebe et al (2016) Anthropogenic carbon release rate unprecedented during the past 66 million years, Nature Geoscience

a study that totally debunks the whole concept of man-made Global Warming, Michael Henehan, Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This study does no such thing. This is factually inaccurate.

But-but-but-but Alexandria Ocasio-Crazy told me we only have 12 years! Michael Henehan, Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: The 12-year figure quoted comes from the 2018 UN “Special Report on Global warming of 1.5ºC,” released last October. In this report, the year 2030—12 years from now—is given as the “point of no return”, if we keep releasing CO 2 at our current rate. What this means is that after this point, it is almost impossible to imagine how CO 2 in the atmosphere could ever be brought back down to levels needed to keep global temperatures less than 1.5 ˚C warmer. This figure comes from the IPCC report scientists—hundreds of scientists from different fields working all around the world. The article has taken this figure out of context, and is comparing it to something very different. What ThinkProgress says is related to the timescales it takes for the maximum effects of the CO 2 released now to take hold. This is not in conflict with the IPCC figure of 12 years cited by AOC—this report talks about the year we must stop releasing CO 2 by in order for the long term knock on effects of this CO 2 release to not be so detrimental to humankind. Marcus Badger, Lecturer in Earth Sciences, The Open University: This confuses the time left to start seriously cutting emissions, with the long tail of impacts that those emissions have. As noted above in this article, there are lags in the climate system that mean CO 2 emissions now will continue to warm the planet for a long time, and some long-acting positive feedbacks (like ice melting) take time.

what this study proves is that there is nothing we can do to stop the Earth’s naturally occurring climate cycles. Michael Henehan, Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam: This study does absolutely no such thing. Its topic wasn’t even related to showing climate cycles—the subject of the paper is looking at the effect on CO 2 of ice sheets scraping soil and weathered rock off the Earth’s surface over ice ages. CO 2 rise and warming that is happening now is entirely something that we have caused (see here for some helpful pointers). We can control our CO 2 release, and so we can control our current rate of warming. What the background conditions do over millions of years is not the point, and is only used in this article as a distraction.