Climate scientists give alarming warning on rising sea levels


Last week the Washington Post’s energy and environment reporter, Chris Mooney, reported on climate scientist James Hansen’s alarming new report.
The world’s most famous climate scientist just outlined an alarming scenario for our planet’s future:

James Hansen has often been out ahead of his scientific colleagues.

With his 1988 congressional testimony, the then-NASA scientist is credited with putting the global warming issue on the map by saying that a warming trend had already begun. “It is time to stop waffling so much and say that the evidence is pretty strong that the greenhouse effect is here,” Hansen famously testified.

GlobalWarmingNow Hansen — who retired in 2013 from his NASA post, and is currently an adjunct professor at Columbia University’s Earth Institute — is publishing what he says may be his most important paper. Along with 16 other researchers — including leading experts on the Greenland and Antarctic ice sheets — he has authored a lengthy study outlining an scenario of potentially rapid sea level rise combined with more intense storm systems.

It’s an alarming picture of where the planet could be headed — and hard to ignore, given its author. But it may also meet with considerable skepticism in the broader scientific community, given that its scenarios of sea level rise occur more rapidly than those ratified by the United Nations’ Intergovernmental Panel on Climate Change in its latest assessment of the state of climate science, published in 2013.

The authors conclude that 2 degrees Celsius global warming—the widely accepted international target for how much the world should limit global warming—is “highly dangerous.”

The new paper by Hansen and colleagues can be read online here.

The new paper takes, as one of its starting points, evidence regarding accelerating ice loss from some parts of the planet’s ice sheets, especially West Antarctica. One of Hansen’s co-authors on the new paper, Eric Rignot of NASA, was the lead author of a 2014 study suggesting that, as one NASA press release put it, the decline of West Antarctica could now be “irreversible.”

In the new study, Hansen and his colleagues suggest that the “doubling time” for ice loss from West Antarctica — the time period over which the amount of loss could double — could be as short as 10 years. In other words, a non-linear process could be at work, triggering major sea level rise in a time frame of 50 to 200 years. By contrast, Hansen and colleagues note, the IPCC assumed more of a linear process, suggesting only around 1 meter of sea level rise, at most, by 2100.

“If the ocean continues to accumulate heat and increase melting of marine-terminating ice shelves of Antarctica and Greenland, a point will be reached at which it is impossible to avoid large scale ice sheet disintegration with sea level rise of at least several meters,” the new paper says.

Using climate models and an analogy with the so-called Eemian period or “Marine isotope stage 5e” — an interglacial period some 120,000 years ago that featured considerable sea level rise — the paper goes on to suggest that major ice loss from both Antarctica and Greenland will change the circulation of the oceans, as large volumes of cold, fresh water pour into the seas. This freshening or decreasing saltiness of the ocean, at both poles, could ultimately block the oceans’ overturning circulation, in which (in the northern hemisphere) warm water travels northward, and then colder, denser water sinks and travels back south again.

As the paper notes, there is already evidence of such cooling in the north Atlantic — presumably due to ice loss from Greenland.

Around Antarctica, meanwhile, sea ice has been growing — potentially another indicator of cooling and freshening at the ocean surface due to ice loss from the frozen continent.

[This is climate skeptics’ top argument about Antarctica — and why it’s wrong]

In the model employed by Hansen and his coauthors, this cooling and freshening of the oceans eventually leads to a shutdown of the oceans’ circulation, and warm waters trapped at depth below a cold fresh surface layer in the Antarctic region, continually eating away at ice sheets from below. It also triggers a globe with ever-warming tropics but cold poles — leading to a large contrast in temperatures between the mid-latitudes and the polar regions.

A larger temperature contrast between the tropics and the poles, the researchers posit, would then strengthen winter storms or so-called extratropical cyclones, which draw their energy from such contrasts. The study therefore contemplates more powerful storms.

There is much more detail in Chris Mooney’s report.

Andrew Revkin, the New York Times’ “Dot Earth” blogger, reported after the release of the report, A Rocky First Review for a Climate Paper Warning of a Stormy Coastal Crisis:

On Thursday, I wrote about the rocky rollout, prior to peer review, of “Ice Melt, Sea Level Rise and Superstorms: Evidence from Paleoclimate Data, Climate Modeling, and Modern Observations that 2°C Global Warming is Highly Dangerous.”

The 66-page, 17-author paper was posted Thursday in Atmospheric Chemistry and Physics Discussions, the pre-publication forum for papers submitted to the European Geosciences Union journal Atmospheric Chemistry and Physics. (You’ll hear more on the benefits and problems of such open-review journals toward the end of this post.)

The paper is a sweeping cross-disciplinary challenge to status-quo science on risks posed by the building greenhouse effect. The authors, led by James E. Hansen, the veteran climatologist-turned-campaigner, stitch a variety of findings and simulations into a worrisome vision of a looming and abrupt collapse of Antarctic ice sheets and a multi-meter rise in storm-raked seas. They directly call for urgent action by the world’s nations at the Paris treaty talks in December.

It’s no wonder the paper made headlines.

But, after less than two days of public review, the paper is being revealed as much more of a rough sketch, a provocation, than a thorough, deeply grounded new thesis.

In science, that’s not a bad thing. It is how progress gets made. Dip the gutsy new idea in the acid bath of peer review. What’s left is new knowledge.

But in the public sphere, with consequential science, the result can be whiplash, at best, and confusion and disengagement at worst.

Don’t take my word for it.

Below you’ll hear from scientists with significant concerns about keystone sections of the paper — on the evidence for “superstorms” in the last warm interval between ice ages, the Eemian, and on the pace at which seas could rise and the imminence of any substantial uptick in the rate of coastal inundation. Reviewers have until mid September to post comments at the discussion site. I hope the scientists below, and others, do so. As the Montell Jordan song goes, “This is How We Do it.”

As Revkin notes: Jim Hansen has posted an essay pressing his argument for urgency. A very positive review was posted Sunday on the journal website by David Archer of the University of Chicago; Judith Curry of Georgia Tech lauds Hansen’s sweep and “maverick” approach, but isn’t impressed with the sea-level conclusion.


James Hansen writes at The Huffington Post, Disastrous Sea Level Rise Is an Issue for Today’s Public — Not Next Millennium’s:

We can always say that more research is needed. Yet as the evidence accumulates at some point a scientist must say it is time to stop waffling so much and say that the evidence is pretty strong. In my opinion, we have reached that point on the sea level issue.

My conclusion, based on the total information available, is that continued high emissions would result in multi-meter sea level rise this century and lock in continued ice sheet disintegration such that building cities or rebuilding cities on coast lines would become foolish.

That brings me to the other reason for publishing in an open-access “discussion” journal, in addition to wanting to give the sea level rise issue more prominence prior to Paris meetings. There is a danger that the public — not too familiar with the scientific method — may misinterpret criticisms, which are natural and healthy for science. I’m hoping that this publication process will make that process clearer and thus also make the reality of the climate situation clearer.

A startling conclusion of our paper is that effects of freshwater release onto the Southern Ocean and North Atlantic are already underway and 1-2 decades sooner in the real world than in the model (Fig. 2). Observed effects include sea surface cooling and sea ice increase in the Southern Ocean around Antarctica and cooling in the North Atlantic. We suggest that the sluggishness (delayed response) of the climate models may be a result of a common excessive small scale mixing in many ocean models, including ours, as discussed previously. One of our objectives is to draw attention to this — I also hope to get support for our group to do climate modeling to investigate the issue, because we recognize several ways that we could improve the model.

Here, I expand on our conclusion that the science indicates 2°C is not a safe target. Indeed, 2°C is not only a wrong target, temperature is a flawed metric due to meltwater effect on temperature. Sea level, a critical metric for humanity, is at least on the same plane. Earth’s energy imbalance is a critical metric, because energy balance must be restored to stabilize climate, which thus informs us about the required limit on greenhouse gases (GHGs). The Framework Convention on Climate Change, agreed upon at Rio in 1992, defines GHGs as the critical metric, saying that GHGs must be stabilized at a level that avoids “dangerous anthropogenic interference” with climate. Why have policymakers turned away from GHG amount to temperature as the metric with a value (2°C) seemingly pulled from a hat? Could it be because 2°C allows politicians to set emission targets to be achieved in the future when they will be out of office? If we stick to the Framework Convention’s GHG metric, we find that the CO2 stabilization level is not 450 ppm or 400 ppm, it is 350 ppm and possibly lower with immediate implications for policy.

The bottom line message scientists should deliver to policymakers is that we have a global crisis, an emergency that calls for global cooperation to reduce emissions as rapidly as practical. We conclude elsewhere and reaffirm in our present paper that the crisis calls for an across-the-board rising carbon fee and international technical cooperation in carbon-free technologies.

Despite the increased threat of sea level rise, I believe that it is still possible to keep impacts of human-made climate change moderate. However, that optimism is based on the assumption that we are close to the point when it is widely recognized that a policy with an across-the-board rising carbon fee that rapidly phases down carbon emissions also makes good economic sense.

Of course, good economics, science and just common sense are in short supply in the Congress.


  1. I won’t address your lack of understanding of the scientific process or scientific research, that is too obviously a feint. I will repeat that you are ignoring the 9,999 doctors who say you will die and that humans are responsible in favor of the 1 that says you won’t die. You are robbing your children and grandchildren of their lives and a decent Earth to live on. Ultimately if this is not fixed our decendents, those that survive, will curse us for having cursed them.

  2. We get these warnings all of the time. I used to here paul erlich talk about it on johnny carson show. We will have to wait until a disaster strikes because that is how the world operates. If you disagree how would you get the climate changers in congress to change?

    • You are correct, Captain. We have had climate change doomsdayers for all of my life. They have been consistently wrong. Yet, today, we are supposed to accept their conclusion that mankind has killed the planet without question or examination. It completely disregards the impact of nature itself despite the unquestionable evidence that climate change has ALWAYS occurred and done so without the input of man. At it’s heart, it is simply another method leftists want to use to control people. their behavior, their thoughts, their money, and most importantly, to punish success through lowered standards of living and redistribution of wealth. I sometimes think the climate is a secondary issue to the “social justice” goals that can be achieved if the issue is properly exploited.

  3. And scientists whose careers, funding and livelihoods depend on “proving” that mankind is the culprit in climate change, and NOT nature doing what it has done for millions of years, are to be believed without question. In fact, because climate change being man caused is a politically correct dogma, questioning these scientists should not be allowed under some sort of penalty of law (said laws to passed as soon as possible). Right, AZbm?

    • The only profiteers in this mess are the fossil fuel industries and they earn millions more than mere scientists. If you are looking for a monetary motive for bogus science, they have a much greater stake in manipulating evidence — whoops, look at the they have done exactly that! I like what Lindsey Graham said recently, if you are told by 9 doctors that if you don’t get treated you will die, why would you believe the one that says ignore them don’t get treated? Only the comparison is closer to 9,999 doctors to 1.

      Insanity is ignoring the train bearing down on you because you choose not to believe it exists. The difference with the climate change train is that it is bearing down on you over the period of decades, the planet Earth is the tracks, you cannot escape. The only solution is to slow down and reverse the train by retiring fossil fuels and substituting renwables. Your deliberate ignorance dooms your children and grandchildren. Ultimately if we can’t reverse the problem there will be worldwide famine. California is not the only place facing unprecidented drought. The Oglala aquifer is drying up too.

      • One does not have to be a “profiteer” to depend on the climate change crisis to earn a decent living. A huge number of scientists and associated staff depend on government grants, Foundation grants, private legacies, contributions, etc., to continue their research into climate change. And pay their mortgages, buy their cars, feed their families, vacation in Cabo, buy clothes for the kids, etc., etc. “Research or die” is understood to be how many academics make their living. Given the tendency of progressives to blame everything evil on mankind, and given that progressives dominate the education industry and the research that accompanies it, and given that historically the climate change doomsayers who blame man for the problems have thrived only in progressive circles, and given that progressives tend to have their fingers on the purse strings of who gets the money, who do you think is likely to get greater funding on the subject of climate change? The researcher who blames it all on man? Or the researcher who sees the possibility that nature may play a bigger role in climate change than man?

        Make no mistake about it, the issue of climate change is more of a political issue than it is a science issue. It is stupid that is how it is, but that is what it has become. It has become political because all of the solutions pushed forward are political in nature. The issue is being used to control people, to control how people live, to redistribute wealth, to destroy unpopular industries, to force the acceptance of unproven but politically correct “solutions”, all in the name of climate change. When there is no real proof that man is the cause, the response is the usual, “but can we afford to take a chance?” My question is, “Can we afford the agenda?”

        The truth is that climate change occurs naturally. We are coming off the end of an unusual period is climate stability. The “proof” that man is the cause always consists of giant leaps of faith that ignores anomalies that don’t fit whatever pattern they are looking for. Within recorded history, the Sahara was a plush oasis bursting with water and agriculture, and then it became a desert. The Gobi Desert was once home to vast grasslands that just disappeared. The temperate forests of South America eventually became rain forests. The climate changed and the land changed with it. And these sweeping changes took place rather quickly without the possible interference of mankind.

        I am pretty certain we are experiencing some measure of climate change, but I don’t think mankind is the reason. I think the punishment of mankind is a political gesture, not a scientific one. THAT is my point of contention. The posters here are all convinced man is the culprit and man must be punished for it. It is no accident that their “solutions” for climate change happen to be the same as their “solutions” for social justice.

        It is the same old politics by another name…that’s all. As the Obama Administration has made clear, “No crisis should be wasted.”

        Einstein said insanity is when you do something over and over expecting a different result. Yet, progressives continue to believe the same discredited climate change “prophets” from the days when I was in College (A LONG time ago). Only then, Paul Ehrlich was predicting ice ages, then it was global warming, now he’s hedged his bets and settled for climate change. He hasn’t ever been correct, yet progressives fall all over themselves to sit at his feet and hear his wisdow.

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