- Climate
Breitbart article baselessly claims a study of past climate invalidates human-caused climate change
Reviewed content
Headline: "Scientists Prove Man-Made Global Warming Is a Hoax"
Published in Breitbart, by John Nolte, on 2019-04-09.
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 CO2 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.)
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
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 CO2 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 CO2 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.
Professor, Met Office Hadley Centre & University of Exeter
Woefully ignorant.
We are certain that humans are responsible for the current rise in atmospheric CO2 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 CO2 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 CO2.
Research Associate, Colorado State University/NASA JPL
The new research shows that a past high CO2 period had lots of global warming, just like we expect from today’s human-driven CO2 changes. Breitbart’s argument is that since CO2 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.
Professor, Earth Observatory of Singapore
Incredibly misleading. The Pliocene is a warning of what CO2 levels can do to the planet
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.
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.
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.
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.
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.
Lecturer in Earth Sciences, The Open University
This article completely misunderstands the point of the science it reports on.
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 CO2 levels on Earth were the same as they are today, but there is one major difference between three million years ago and today…
Lecturer in Earth Sciences, The Open University
This part of the article does accurately report the findings of the paper it links to: CO2 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 CO2 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 CO2 records, Nature
- 2- Willeit et al (2019) Mid-Pleistocene transition in glacial cycles explained by declining CO2 and regolith removal, Science Advances
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 CO2 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 CO2 emissions globally were higher as continental spreading rates changed, for example. Saying that CO2 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.
CO2 levels were the same then as they are now
Lecturer in Earth Sciences, The Open University
Yes, naturally CO2 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 CO2-driven climate change, and these record a broad decline over that time, with the Pliocene the last time CO2 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.
Lecturer in Earth Sciences, The Open University
This confounds natural variations in CO2 in the geological past with human-caused emissions today. Yes, CO2 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.
Research Associate, Colorado State University/NASA JPL
This entire article’s “proof” is just saying that “higher CO2 happened before humans, therefore humans can’t cause higher CO2“.
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 CO2 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.
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.”
Lecturer in Earth Sciences, The Open University
This is where the real logical fallacy of this article becomes clear. Indeed, when CO2 was naturally as high as we have caused it to be now, the world was much warmer than today because of the naturally higher CO2. It therefore follows that the high CO2 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?
Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam
What this study tells us is that the last time CO2 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 CO2 levels) that these ice bodies will melt in the future from anthropogenic CO2 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 CO2 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?
Professor, Met Office Hadley Centre & University of Exeter
Because the amount of CO2 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 CO2 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).
Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam
It is possible because CO2 sources (e.g. volcanic degassing) and CO2 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
Lecturer in Earth Sciences, The Open University
The study does the complete opposite of this, by showing that high levels of CO2 has caused a warmer world in the past, it confirms what we know about how anthropogenic CO2 emissions are and will continue to warm the planet.
running through cycles where the temperature might fluctuate a bit.
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 CO2 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?
Postdoctoral Researcher, GFZ Helmholtz Centre Potsdam
Again, this is possible because at various times in the Earth’s history, sources and sinks of CO2 into the atmosphere have had varying strengths. These are natural changes in CO2 levels that have slowly happened for 100s of millions of years. However, modern CO2 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,
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!
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 CO2 at our current rate. What this means is that after this point, it is almost impossible to imagine how CO2 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 CO2 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 CO2 by in order for the long term knock on effects of this CO2 release to not be so detrimental to humankind.
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 CO2 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.
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 CO2 of ice sheets scraping soil and weathered rock off the Earth’s surface over ice ages.
CO2 rise and warming that is happening now is entirely something that we have caused (see here for some helpful pointers). We can control our CO2 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.
nothing we can do to stop the Earth’s naturally occurring climate cycles.
Professor, Met Office Hadley Centre & University of Exeter
Actually, studies suggest that we may already have postponed the next ice age by adding extra CO2 to the atmosphere which will take a long time to be removed by natural processes, and hence has committed the Earth to warmer temperatures than it would otherwise have had.
Lecturer in Earth Sciences, The Open University
This is not true, and there is good evidence that human CO2 emissions stopped the initiation of another ice age*
- Ganopolski et al (2016) Critical insolation–CO2 relation for diagnosing past and future glacial inception, Nature
