Friday, July 14, 2017

Scientists explain what New York Magazine article on “The Uninhabitable Earth” gets wrong

FromClimate Feedback. Excerpt:
"Analysis of "The Uninhabitable Earth"
Published in , by on
Sixteen scientists analyzed the article and estimated its overall scientific credibility to be ‘low’.
A majority of reviewers tagged the article as: , , .

SUMMARY

New York Magazine published an article by David Wallace-Wells detailing the potential impacts of climate change if no action is taken to reduce greenhouse gas emissions. Much of the article explores “worst case” scenarios of change in the climate system and the resulting impacts on human populations.
Scientists reviewed the article to determine whether the descriptions of those scenarios accurately reflect the state of scientific knowledge. The New York Magazine article has triggered a number of responses debating the merits of the decision to focus on worst case scenarios, but our review simply addresses the scientific accuracy of the article.
The reviewers found that some statements in this complex article do misrepresent research on the topic, and some others lack the necessary context to be clearly understood by the reader. Many other explanations in the article are correct, but readers are likely left with an overall conclusion that is exaggerated compared to our best scientific understanding.
See all the scientists’ annotations in context
Update 13 July 2017: The article has been updated to include several comments received after the time of publication. The main conclusion of the analysis is unchanged.

GUEST COMMENTS

Michael Mann, Professor of Meteorology, PennState University:
The article paints an overly bleak picture by overstating some of the science. It exaggerates for example, the near-term threat of climate “feedbacks” involving the release of frozen methane (the science on this is much more nuanced and doesn’t support the notion of a game-changing, planet-melting methane bomb. It is unclear that much of this frozen methane
can be readily mobilized by projected warming).
Also, I was struck by erroneous statements like this one referencing “satellite data showing the globe warming, since 1998, more than twice as fast as scientists had thought.”
That’s just not true. The study in question simply showed that one particular satellite temperature dataset that had tended to show *less* warming that the other datasets, has now been brought in line with the other temperature data after some problems with that dataset were dealt with.
Ironically, I am a co-author of a recent article in the journal Nature Geoscience (see e.g. this piece), using that very same new, corrected, satellite dataset, that shows that past climate model simulations slightly **over-predicted** the actual warming during the first decade of the 21st century, likely because of a mis-specification of natural factors like solar variations and volcanic eruptions. Once these are accounted for, the models and observations are pretty much in line—the warming of the globe is pretty much progressing AS models predicted… which is bad enough.
The evidence that climate change is a serious problem that we must contend with now, is overwhelming on its own. There is no need to overstate the evidence, particularly when it feeds a paralyzing narrative of doom and hopelessness. [Read more]

REVIEWERS’ OVERALL FEEDBACK

These comments are the overall opinion 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:
While it is clear that ongoing warming of the global climate would eventually have very severe consequences, the concept of the Earth becoming uninhabitable within anywhere near the timescales suggested in the article is pure hyperbole. The author has clearly done very extensive research and addresses a number of climate threats that are indeed major issues, but generally the narrative ramps up the threat to go beyond the level that is supported by science.

Daniel Swain, Postdoctoral Fellow, University of California, Los Angeles, Institute of the Environment:
This is an unusual piece in that it accurately describes some of the most dire consequences of unabated global warming but focuses almost exclusively on worst case scenarios. In doing so, it provides a compelling narrative of what could happen in the future, but does not accurately characterize the likelihood of particular outcomes relative to what is justifiable based upon existing scientific evidence.

Charles Koven, Research Scientist, Lawrence Berkeley National Lab:
The article, while it does thoughtfully discuss some serious implications of climate change, also goes beyond the evidence in a number of instances of its exploration of worst-case scenarios.

Alexis Berg, Associate Research Scholar, Princeton University:
This article focuses on the high-end scenario for global warming—high emissions and/or high climate sensitivity, high impacts. It selects recent research that highlights these outcomes. I am sympathetic to the author’s efforts to raise awareness about such scenarios, including impacts that are not always well discussed, and agree that we tend to focus too much on median outcomes. Nevertheless, I think the article would have gained from a more explicit acknowledgement that this particular focus is the goal of the article, as well as a from an explicit discussion (even if only qualitative) of the probabilities associated with these scenarios. Absent that, I am afraid the article, as such, feels misleading, or at least confusing for the general public.
In addition, the article contains a number of claims that are factually wrong, and a number of claims that are, to my knowledge, not substantiated by research.
I was also concerned by the implied claim that this article, being written after interviews with many climate scientists, somehow reflects scientists’ true opinion about global warming. I don’t believe it does.
What this article suggest to me is that we, as as community of scientists and science journalists, need to find a better way to more accurately discuss climate change projections and to convey the associated risks to the public.

Peter Neff, Postdoctoral research associate, University of Rochester:
In what seems an ode to new journalism, the author takes significant literary license to leverage information grounded in truth and paint an apocalyptic picture of extreme future scenarios possibly driven by anthropogenic climate change. Ambiguous references to studies, events and examples severely impairs credibility, as does a complete disregard for nuance.

Christopher Colose, Postdoctoral Research Fellow, NASA GISS:
There are many arguments in this article at the interface of climate instability, socio-political disruption, and general global security. They are, however, clumsily wrapped together and doesn’t reflect well the actual risk posed by climate change.
A general comment concerning the climate response to future carbon emissions—one of the emergent insights from decades of research is that linearity is too powerful of a tool to be abandoned lightly. In this context, it is better to think of future warming as smoothly monotonic in our total carbon emissions rather than behaving erratically due to significant non-linearities in the system.
There is no evidence that a very abrupt methane source(s) will be readily mobilized into the atmosphere. Such scenarios are not supported by process studies, it is not emerging observationally, and is not borne out paleoclimatically (particularly in the mid-Holocene or Eemian interglacial, where high latitude summers were hotter than today). A small trickle of CH4 release is very plausible, but methane becomes converted to CO2 pretty quickly in Earth’s atmosphere, and there’s already some 200 times more CO2 in the air than CH4. These types of carbon cycle feedbacks will likely give the direct anthropogenic carbon input just a small boost in the near future.
Similarly, it’s not obvious that there are any significantly missing feedbacks that should radically alter the linear perspective (certainly, any under-representation of surface albedo feedbacks in current models are unlikely to be the difference maker, since the polar regions make up a very small percentage of the globe and the surface contribution to the planetary albedo is somewhat masked by clouds).
A Younger Dryas event today would likely be quite disruptive (the global mean temperature changes were quite modest, but the extratropical temperature re-organizations would still be significant); however, the processes leading to an event like this are pretty unique to a glacial climate undergoing melting, and is unlikely to occur in a warming world during our present interglacial.
Actual numbers are important here. The global temperature increase could indeed reach 4-5 degrees by 2100, if humans don’t do anything to our emissions, and beyond this patches of uninhabitable areas (for humans) could start to open up in the tropics, due to heat stress limits imposed by the evaporative limits of our body. Indeed, a world 5+ degrees warmer is a big cause for alarm, even if the world takes a linear path to that mark. The world also does not end in 2100, and while it is tempting to think of later dates as “very far off,” it is worth reminding ourselves that we would live on a different planet had people of the Viking era industrialized and emitted carbon uncontrollably.
Nonetheless, the near future climatic fate of New York probably looks more like the climate of South Carolina or Georgia than something from a Mad Max movie. This is still an important basis for concern given that the socio-political infrastructure that exists around the world is biased toward the modern climate.
Many of the nightmare scenarios in this article, such as no more food, unbreathable air, poisoned oceans, perpetual warfare, etc. are simply ridiculous, although food security is indeed an issue at stake (see David Battisti’s comments). A “business-as-usual” climate in 1-2 centuries still looks markedly different than the current one, but there’s no reason yet to think much of the world will become uninhabitable or look like a science fiction novel.

Victor Venema, Scientist, University of Bonn, Germany:
We are taking the climate system out of known territories. There will be many surprises and they are what worry me the most. Uncertainty is not our friend and that makes it very hard to say which worst case scenarios are unrealistic.
The bigger the stakes the smaller the acceptable risks. A risk someone may be willing to take personally will be larger than the risk one takes with a community, a country or civilization.
In that respect it is good that the article explores what surprises may be in store and talks about scenarios that are not likely, but a large part of the total risk.
However, unfortunately often statements are inaccurate, wrong or are missing important context. It could be that surprises we did not think of yet compensate for that, but for now I would say the article exaggerates the risks of climate change.

Charles Koven, Research Scientist, Lawrence Berkeley National Lab:
The article, while it does thoughtfully discuss some serious implications of climate change, also goes beyond the evidence in a number of instances of its exploration of worst-case scenarios.

Benjamin Horton, Professor, Rutgers University:
Most statements in the article are based on peer-reviewed literature.

Pierre Friedlingstein, Professor, University of Exeter:
The article is very alarmist, making very strong statements with very little (if any) support. Implying that climate scientists support the article, which I find hard to believe.
Such article does not help at all. It’s just too easy to prove it wrong and hence imply that the entire climate change issue is exaggerated.

Notes:
[1] See the rating guidelines used for article evaluations.
[2] Each evaluation is independent. Scientists’ comments are all published at the same time."

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