When Are We Going Underwater?

Renowned scientist James Hansen says sea level is rising faster than expected—but did his study’s publication violate scientific norms?

Photo: Oliver Clarke/Flickr

A recent paper by climatologist James Hansen has the Internet buzzing—well, at least the nerdy part. NASA’s former climate guru predicts a much more rapid and imminent doomsday than his colleagues, but much of the controversy has focused on Hansen’s publicity-grabbing tactics rather than his research.

Here’s what you need to know.

Who is James Hansen?

Hansen became the most prominent climatologist in the United States—and possibly in the history of the world—in 1988, when he told Congress that global warming was 99 percent certain to be the result of human activities.

His testimony (shown below) before the Senate Energy and Natural Resources Committee created an instant media frenzy, because he abandoned the cautiousness and caveats traditional in scientific talks. “It is time to stop waffling so much,” he told the senators—it took some chutzpah for the director of NASA’s Institute for Space Studies to say that to the U.S. Senate.

Photo: NASA

Hansen has no shortage of chutzpah, though, which has made him a controversial figure in the 27 years since his testimony. He accused the Bush administration of censoring him in 2006. He calls coal-fired power plants “factories of death” and has demanded an immediate moratorium on new ones. Hansen is the bête noire of climate change deniers, who call him “delusional.” He has riled mainstream environmentalists as well by repeatedly calling for the United States to build more nuclear reactors. (Hansen has likened the notion that we can rely completely on wind and solar in the near future as “equivalent to believing in the Easter Bunny and the Tooth Fairy.”)

Since leaving NASA in 2013 at the age of 72, Hansen has repeatedly criticized climatologists for underplaying the perils we now face. He argues that the commonly accepted goal of limiting global average temperature increase to two degrees Celsius isn’t ambitious enough. He has also accused the Intergovernmental Panel on Climate Change of underestimating the risk of sea-level rise, which leads us to the current controversy…

What does Hansen’s paper say?

Hansen was the lead author of a paper published Thursday entitled “Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming is highly dangerous.” (You can read the paper here, but be advised that it’s a fairly dense 64 pages.) The terrifying upshot is that Hansen believes ice in Greenland and Antarctica will melt 10 times faster than previous estimates predicted, and there will be a 50-year period later this century or early in the next during which sea levels will rise 10 feet. Such an increase would submerge the homes of millions of Americans in New York, New Orleans, Miami, and many other cities. Hansen again argues that we should move away from the two-degree target and instead try to reduce the atmospheric concentration of carbon dioxide from about 400 parts per million to 350 parts per million.

It’s important to note that Hansen is not alone on this. Sixteen other scientists worked on the paper, including climatologists from NASA, the California Institute of Technology’s Jet Propulsion Laboratory, and the Institute of Earth Environment at the Chinese Academy of Sciences. This is an all-star lineup.

The research combines a wide variety of data, from ice cores to historical sea-level measurements from the Eemian warm period that happened between 130,000 and 115,000 years ago. It’s all fed into a computer model, of course, which makes Hansen’s conclusions difficult for a lay reader to analyze. That brings us to the other noteworthy aspect of Hansen’s paper…

Why was the publication process so controversial?

Traditionally, the scientific review process occurs outside of public view and can take months. Many journals, however, now take a different approach. They post submitted papers in online forums, where anyone can read the draft. Peer reviewers also post their comments and suggestions online for the public to see. Hansen’s paper is now undergoing this process. It was posted Thursday in Atmospheric Chemistry and Physics Discussions, a forum of the European Geosciences Union. There’s nothing strange or nefarious in that.

What was extremely unusual was the publicity blitz. Even before the paper came online, a public relations firm working with Hansen alerted an elite group of journalists to the posting and organized a press conference. The PR firm offered those reporters a sneak peek at the research and the opportunity to publish articles on it before the draft of the paper went live.

A number of outlets, like the Washington Post, chose to cover it. Other journalists, like seasoned climate-beat reporter Seth Borenstein of the Associated Press, decided it would be premature to report on a study before the peer reviews had begun. Both approaches seem legitimate, in my view. If the newspaper feels its primary role is to notify the public of news as it happens, then covering the study as soon as it’s available makes sense. (Assuming that the reporter informs the reader that the paper wasn’t yet peer-reviewed, as most did.) If, however, a journalist regards judgment and filtering among his most important functions, then it makes more sense to wait for the peer-review process to pan out.

What are scientists and other influential voices saying about it?

Hansen was clearly looking to make a media splash. He told reporters that he opted for publication before peer review because he wanted to make sure that the research got into the hands of delegates to the next United Nations Conference on Climate Change that begins on November 30 in Paris.

I doubt, however, he appreciates the sort of media splash he got. After the initial reporting of the study, much of the discussion has centered on Hansen’s approach to publicizing his research rather than the research itself. In addition, publishing the draft prior to peer review means that its flaws and weaknesses will receive heavy public scrutiny. In a traditional behind-closed-doors review, Hansen would have had an opportunity to address those concerns prior to publication.

Andrew Revkin, author of the Dot Earth blog in the New York Times and owner of an excellent Rolodex of scientific contacts, has been helpfully publishing the responses of several scientists to Hansen’s paper and his publication methods. Max Engel of the University of Köln, for example, argues that Hansen et al.’s assumptions about heavy storm activity during the Eemian—the warm period they use as an analog for our future world—are questionable. Tad Pfeffer, a glaciologist at the University of Colorado, raises interesting questions about how Hansen can be certain of a 50-year period of intense sea-level rise but not be able to put even a broad estimate of when that will begin. Renowned climatologist Michael Mann (creator of the famous hockey stick graph and second only to Hansen himself in the denier’s list of most-hated scientists) points out that Hansen’s method of estimating sea-level rise tends to introduce errors by basing assumptions about future conditions on current conditions. There have been positive reactions as well. University of Chicago geophysicist David Archer calls the paper a “masterwork” and praises the team for its clever and convincing use of the Eemian period as a model for the future.

The controversy over Hansen’s approach to publishing and publicizing the paper, however, seems far less interesting to scientists than to journalists. Mann begrudgingly accepts it as not “entirely without precedent.” Steven Leibo, a political historian at the Sage Colleges, provides the most interesting comment by comparing Hansen to Paul Krugman—both highly credentialed researchers who have transitioned into a more public-facing role.

So now what?

It’s a shame that the discussion of Hansen’s research has focused so much on the work of a PR firm, because there’s only one question that really matters in all this: Is Hansen right? If he is, we ought to be very, very concerned. (I certainly am, since my apartment building would likely be one of those to go underwater.)

All we can do is let the process play out. In the coming weeks and months, Hansen’s peers will pore over his data, his assumptions, and his conclusions. Then his ideas will be integrated into mainstream assessments and forecasts.

Unfortunately for all of us, though, this week was probably the high-water mark for public discussion of the paper.


onEarth provides reporting and analysis about environmental science, policy, and culture. All opinions expressed are those of the authors and do not necessarily reflect the policies or positions of NRDC. Learn more or follow us on Facebook and Twitter.

Join Us