Jerry Mahlman (Photo: NOAA)

Jerry Mahlman, a leading climatologist who for many years headed the NOAA Geophysical Fluid Dyamics Lab, died on November 28. In the 1990s I saw him play a pioneering role in interpreting the science of global warming to policymakers and the public. In 2006, in comments we posted, he called out NOAA Administrator Lautenbacher for political interference with science communication at his agency. A sad loss of a terrific guy and a great asset to the community.  

Dr. Mahlman spent most of his career modeling how Earth’s atmosphere responds to the steady buildup of greenhouse gases. From 1970 to 2000 he worked at the Geophysical Fluid Dynamics Laboratory of NOAA in Princeton, NJ, serving as Director from 1984-2000, and was a Professor in Atmospheric and Oceanic Sciences at Princeton University. After retiring from GFDL, he was a senior researcher at the National Center for Atmospheric Research in Boulder, CO.

Among his many awards he received the prestigious Carl-Gustaf Rossby Research Medal from the American Meteorological Society and the Presidential Distinguished Rank Award – the highest honor awarded to a federal employee.  He was a Fellow of the American Meteorological Society and AMS’ Sigma Xi Distinguished Lecturer, and a Fellow of the American Geophysical Union and the first Jule Charney Lecturer of the AGU.

Twenty years ago, when I was on the professional staff of the House Committee on Science, Space, and Technology, he influenced my thinking about the climate science-policy relationship.  It was a time when only a small number of climate scientists had yet ventured forth seeking new ways to communicate about climate change in a wider public arena.  Scientists, federal research program executives, and members of Congress alike tended to emphasize the development of a predictive understanding of global change in the Earth system as a precondition for rational policymaking. This formulation was useful to scientists who preferred to stick to basic research and avoid the challenge of public communication. It was useful to feds who wanted to keep their programs funded while avoiding political controversy on global warming. And it was useful to politicians who could avoid taking action by pointing to scientific uncertainties and the limits of climate change prediction.

But it was an inadequate formulation, which needed to evolve toward talking in terms of an ongoing relationship between advancing scientific understanding and the ongoing policy process, the need for decisionmaking in the face of uncertainty, and climate change as a risk assessment and risk management problem. We needed scientists who would step up to learning how to communicate, and who didn’t shrink from giving policymakers a push. We had Steve Schneider, Bob Watson, Jim Hansen, and precious few others, one of whom was Mahlman.

I was struck by a piece he had written [need citation here] that, in effect, challenged the myth of seeking, or requiring, a comprehensive predictive understanding as a basis for rational policymaking – what might be called the founding premise of the U.S. Global Change Research Program. Mahlman was the head of one of the nation’s leading climate modeling centers, where scientists practiced the state of the art in developing that predictive understanding – and he always argued for strong support for this kind of climate research, and for the global climate observing systems needed to provide data for monitoring the Earth system and as input to models. But what he said, to paraphrase from memory, was: elected officials, you can’t wait for predictive uncertainty about climate change to go away. That’s not going to happen any time soon. And (here’s the key point) even if I could tell you, with precise certainty, exactly how much the planet will warm between now and some point in the next century, that wouldn’t give you the answer as to what you need to do. The global warming problem is real. You need to deal with it. You need to think about your options and start making policy on the basis of what we have learned, even as we scientists continue to work on improving our understanding and predictions.

Among the hearings I did staff work on developing for the House Science Committee was one in November 1993 titled “Climate Change Action Plan and Assessment” at which Mahlman testified (US Government Printing Office, 1994, ISBN 0-16-044463-2). It was an excellent hearing if I do say so myself.  This was well before the IPCC Second Assessment Report in 1995, which was the first to attribute observed global warming at least in part to human activity, with the iconic conclusion that “the balance of evidence suggests that there is a discernible human influence on global climate.” In his testimony, Mahlman experimented with a way of expressing levels of confidence in climate science findings in non-technical terms. An excerpt from his opening oral statement:

The uncertainty in such vital areas as ocean circulation and cloud processes should gradually diminish. However, let me state at the outset, none of the uncertainties that I discuss today can make current concerns about global warming go away. This problem is very real and it will be with us for a very long time.

Today I’ll give my estimates of current scientific confidence based upon simple betting odds. In my betting odds scenario, by “virtually certain,” I mean that there is no plausible alternative, or that the bookies would throw it out of the bets. “Very probable” means I estimate 9-out-of-10 chance that this will happen within the range that science is predicting. …

Human-caused increasing greenhouse gases, virtually certain. …

Radiative effect of increased greenhouse gases, virtually certain. ….

Long time scales in the problem, virtually certain. We all know that it takes decades to centuries to produce the buildup of greenhouse gases. Much less appreciated is that a future return to normal from high carbon dioxide levels would require many additional centuries. This is an overlooked point that must be considered in future policy deliberations.

Global-mean surface warming, 9 out of 10. For the middle of the next century, global-mean surface warming is estimated to be in the range of 2 to 8 degrees Fahrenheit. The largest uncertainty is due to the effects of clouds. My own personal opinion is that the warming a half century from now is more likely to be in the lower half of this renage.

Reduction of northern sea ice, 9 out of 10. …

Rise in global mean sea level, 9 out of 10. … Continued sea level rise is expected for many centuries, probably to much higher levels.

Summer midcontinental dryness and warming, 2 out of 3. … This drying effect has the potential to be a major detrimental effect of greenhouse warming. … (pp. 82-83)

Ten years later, he made a stronger statement in testimony before the Senate Committee on Commerce, Science, and Transportation at a March 3 hearing on “Climate Change” — and used a sharper tone in challenging policymakers. An excerpt (boldface added):

Today, I will be speaking bluntly and simply about what we know about global warming, and its implications for society. Global warming is real and is a phenomenon that humans have created. Climate scientists worldwide have understood its essence since the so-called “Charney Report” of the National Research Council 25 years ago. Our burning of fossil fuels (coal, oil, and natural gas) is the indisputably direct cause of the ever-increasing concentrations of carbon dioxide in the atmosphere. This added carbon dioxide acts directly to warm the planet. There is no scientific controversy about these facts. The eventual warming amounts for Earth are expected to be substantial, but with some remaining uncertainty concerning how much warming we will receive for given scenarios of future amounts of carbon dioxide, and other “greenhouse” gases.

We do have strong information that provides a sharper perspective on the policy-relevant impacts of global warming. For example:

* A doubling of atmospheric carbon dioxide amounts is expected to occur within this century, almost independent of expected progress in emissions mitigation measures.

* Another 3-6 degrees Fahrenheit global warming is expected to occur this century, with continued warming thereafter.

* Global sea level is expected to rise steadily over the next 1000 years, with ominous very long-term consequences.

* Summer Arctic sea ice is expected to disappear by the middle of this century.

* Semi-arid continental areas are expected to have substantially less soil moisture in summer, with daunting implications for agriculture.

* Humid subtropical climates such as in the southeast U.S. are expected to have summertime heat index increases that well exceed the temperature increases.

* Tropical storms are expected on average to have stronger winds, and much more rain. Other projected changes are more uncertain than this “very probable” list, but could also have daunting consequences.

I am not here today, or on any day, to advocate a specific public policy choice on this very important, but widely evaded, global problem. I do, however, believe that it is scientists’ obligation to communicate the science of global warming, including its remaining uncertainties, to leaders and stakeholders, worldwide. I would also argue that it is our responsibility to offer our science-based perspectives on the available policy options, as well as their strengths and weaknesses. Clearly, improvements in this two-way communication are necessary.

The viable policy options to deal with this problem meaningfully are very straightforward, but dauntingly difficult in their application. The basic major options are:

* Mitigation of Greenhouse Gas Emissions: A world-wide effort to reduce the emissions of carbon dioxide and other greenhouse gases substantially over the next half century, and likely much longer

* Adaptation: Altering society and earth’s life systems, in many ways, to be more resilient to global warming, in the U.S. and globally.

* Coping: Proceed with “business as usual”, and let the detrimental consequences be dealt with by future generations. This appears to be the unstated current national, and international, global warming “strategy”. My opinion is that our descendents are likely to judge us harshly for our not yet having begun to address this problem meaningfully.

From an interview with the New York Times in 2003:

A CONVERSATION WITH: JERRY MAHLMAN; Listening to the Climate Models, And Trying to Wake Up the World

… JM: In 1979, a National Academy of Sciences report said the climate was likely to warm if you keep putting CO2 into the atmosphere. Though in the intervening years, we’ve gotten much more information proving this, little has been done since on the policy side of reducing CO2 emissions. All of this raises deep ethical questions. For me, the biggest one is, Do we accept a responsibility for the welfare of our descendants and for life in general 100, 200, 1,000 years from now?

As quoted in the New York Times (Nicholas Kristof column) on March 5, 2006, with an increased sense of urgency:

“Historians of science will be brutal on us,” said Jerry Mahlman, a climate expert at the National Center for Atmospheric Research. “We are right now in a state of deep denial about how severe the problem is. Political people are saying, ‘Well, it’s not on my watch.’ They’re ducking for cover, because who’s going to tell the American people?”
“Are we an intelligent species or not?” Dr. Mahlman asked. “Right now, the evidence is against it.”

He pushed back against political interference with climate science communication. From the New York Times interview in 2003:

NYT: Could you be wrong with your predictions on global warming?

JM: It would be wonderful to be wrong. Unfortunately, these projections are based on strong science that refuses to go away. Oh sure, there are people insisting that warming is just a part of natural weather cycles, but their claims are not close to being scientifically credible. And while there certainly are long climate cycles, the fact is that the strong warming we are seeing is happening in an era of ever increasing CO2 emissions.

These people remind me of the folks who kept trying to cast doubt on the science linking cancer to tobacco use. In both situations, the underlying scientific knowledge was quite well established, while the uncertainties were never enough to render the problem inconsequential. Yet, this offered misguided incentives to dismiss a danger.

Global warming is unpleasant news. The costs of doing something substantial to arrest it are daunting, but the consequences of not doing anything are staggering. …

NYT: Did you ever see Henrik Ibsen’s ”An Enemy of the People,” about a health worker whose life is destroyed after he tells his community about typhoid in its water supply?

JM: I am familiar with the story. I too have been under tremendous pressure at times to tone down my message, to make the science appear less alarming. When I was head of my laboratory at Princeton, I was often asked to give Congressional testimony.

In three events, two senators and a congressman — I won’t give you their names because I consider that cheap — attacked me in the most personal way. They were trying to intimidate me into denying my testimony. Also, during my tenure in government, there were three instances where people in the government attempted to alter my prepared testimony. In each instance, I successfully challenged the requested changes as being scientifically insupportable.

In 2006 Mahlman spoke out about restrictions on public communication by climate scientists at the National Oceanic and Atmospheric Administration (NOAA), implicating Department of Commerce Under Secretary Adm. Conrad Lautenbacher, the NOAA Administrator. We posted his comments on March 10, 2006 (Former NOAA Lab Director: “Climate scientists within NOAA have been prevented from speaking freely”), which included:

Jerry Mahlman, Comments on Adm. Conrad Lautenbachers “Message From the Under Secretary—Encouragement of Scientific Debate and Transparency Within NOAA”

I was both heartened, and discouraged, by the statements of Dr. Lautenbacher on the censorship and distortion of climate (and other) sciences within the National Atmospheric and Oceanic Administration over the past year or so.  As a former 30-year scientist at NOAA’s Geophysical Fluid Dynamics Laboratory (and 16 years as its Director),  I am confident that my statements are correct, appropriate, and consistent with the views (and NOAA’s current suppression thereof) of NOAA’s pioneering and leading scientists on the looming mega-challenge of human-caused climate warming.

Contrary to Dr. Lautenbacher’s assertions, I state emphatically that climate scientists within NOAA have indeed recently been systematically prevented from speaking freely to anyone outside NOAA who is seeking information on the new scientific insights that have added to the prodigious amount of information gained recently on the scientific understanding of our inexorably warming planet.  It is quite distressing that Dr. Lautenbacher has chosen in his “Message” to pretend that NOAA climate scientists have not been forbidden from speaking freely about their scientific contributions to global warming science, unless the call is accompanied by an Administraton “minder” of the conversation.  From my recent personal experience, his contention is simply not true. A number of NOAA scientists have directly and openly disagreed with Lautenbacher’s statements that deny his direct connection with censorship of climate science….

That was a timely intervention in sticking up for the science community, including his own former colleagues at GFDL, during a dark period.  R.I.P. Jerry — you will be remembered.

See this fine memory piece by University of Michigan Prof. Ricky Rood, which includes some good photos of Jerry, out of the lab and into the hinterlands: Jerry Mahlman: Plants and Birds and Rocks and Things

Obituary in Longmont (Colorado) Times-Call, December 2