Michael MacCracken says Richard Lindzen’s April 16 op-ed in Newsweek, “Why So Gloomy?” contains numerous misleading statements and statements that are contrary to the international scientific consensus.  MacCracken takes Lindzen’s argument apart, line by line. 


Lindzen’s Newsweek Op-ed: Misleadingly Rosy

Dr. Michael C. MacCracken
Chief Scientist for Climate Change Programs
Climate Institute, Washington DC*

Richard Lindzen’s op-ed “Why So Gloomy?” which was published in the April 16, 2007 issue of Newsweek and distributed by MSNBC, includes roughly a score of statements that are contrary to the international scientific consensus and, in many cases, quite misleading.  Specific comments are offered after each of his paragraphs.

Lindzen’s first paragraph: “Judging from the media in recent months, the debate over global warming is now over. There has been a net warming of the earth over the last century and a half, and our greenhouse gas emissions are contributing at some level. Both of these statements are almost certainly true. What of it?”

1.  The phrase “the debate over global warming is now over” does not mean that there is no more to learn scientifically, as Lindzen’s comment suggests, but that theoretical analyses combined with observational evidence have together produced a broad scientific consensus that human activities have become the primary factor influencing the global climate. This does not mean that there is no more science to be done, but instead that, in the risk-based framework that society uses in its decision-making, the uncertainties in the science are now small enough to justify public action that will prevent more serious changes in the future.

Lindzen’s second paragraph: “Recently many people have said that the earth is facing a crisis requiring urgent action. This statement has nothing to do with science. There is no compelling evidence that the warming trend we’ve seen will amount to anything close to catastrophe. What most commentators­—and many scientists—­seem to miss is that the only thing we can say with certainly [sic; he means “certainty”] about climate is that it changes. The earth is always warming or cooling by as much as a few tenths of a degree a year; periods of constant average temperatures are rare. Looking back on the earth’s climate history, it’s apparent that there’s no such thing as an optimal temperature­a climate at which everything is just right. The current alarm rests on the false assumption not only that we live in a perfect world, temperaturewise, but also that our warming forecasts for the year 2040 are somehow more reliable than the weatherman’s forecast for next week.”

2. Lindzen’s use of words such as “compelling” and “certainty” is an attempt to impose a decision framework that is not representative of how society, business, or governments make decisions. While the scientific process is designed to ultimately produce information with a high level of confidence, social decisions are made in a different way. If certainty were required for every action, no one would ever start a small business, drill for oil, or drive a car­virtually everyone makes a probabilistic judgment about likelihood or the most likely outcome. Projecting societal development and changes in climate over coming decades will never be certain, ­but a range of outcomes encompassing the most likely set of possibilities can be developed, and when all such scenarios indicate that climate change and its associated impacts are very likely to be significant, even dangerous or catastrophic, then societal decision makers need to be taking the issue seriously.
3. Lindzen’s contention that “there is no compelling evidence that the warming trend we’ve seen will amount to anything close to catastrophe” assumes that the warming trend of the past, linearly extrapolated to the future, will give an accurate indication of future effects. Doing so, he fails to recognize how committed the world is to further emissions of greenhouse gases that will force much more extensive climate change in the future if very strong reductions in emissions are not enacted. Lindzen also fails to mention that further warming is very likely to substantially accelerate sea level rise, committing the world in the not too distant future, if not already, to melting a substantial portion of the Greenland and West Antarctic Ice Sheets, producing sea level rise of at least several meters, quite possibly within a few centuries. During the last interglacial about 125,000 years ago, when global average temperatures were not substantially warmer than at present, sea level was 4-6 meters (about 13 to 20 feet) higher than at present. The last time in Earth history when the global average surface temperature was as warm as the IPCC projects for 2100 in its mid-range scenarios, there was very little polar ice and sea level would have been roughly 70 meters (over 200 feet) higher than at present. A recent World Bank study on the effects of sea level rise estimated that a minimum of 57 million people would be displaced by a 1-meter rise in sea level and many coastal cities and communities would be at significant risk. If this does not provide a “compelling” basis for action, perhaps Lindzen would like to invest his retirement funds in the few remaining companies still selling insurance to those living on low-lying coastlines.
4. Indeed, as Lindzen points out, the Earth’s climate has always been changing; but by how much, how fast, and when did these changes occur? Prior to the changes in climate initiated by the Industrial Revolution, changes in global average temperature over the whole period of societal development were likely less than 0.5ºC (about 1ºF); this is only about 10-20% of the change projected for the 21st century. The last time that global average temperatures were as warm as they will be in 2100 was tens of millions of years ago, long before the advent of civilization, or even the human species. In addition, the rate of warming over the 21st century is projected to be far faster than has occurred over such periods since the end of the last glacial period, again long before societal development. On a regional basis, past fluctuations of temperature have been on the order of a few degrees, and when these have occurred over extended periods, the environmental and societal impacts have been very large. Even when the end results have been somewhat beneficial, the transition has generally been difficult. Projected changes for the 21st century over land and in mid and high latitudes will be larger than the projected change in the global average temperature, so again, past experience will provide little guidance for the future.
5. Lindzen’s assertion that there is no ideal temperature might be true on a planetary wide basis, but society has developed based on the current climate, generally tuning what it does (e.g., the crops it grows, the water systems it has built, the locations of communities along the coast) to what we have now. Changing temperature, precipitation, and sea level, as is projected, will cause serious disruption and the requirement for expensive adaptation, even if the altered state can eventually be adapted to. Ultimately, any discussion of an ‘optimal climate’ begs the question of ‘optimal for whom?’ All climates will be optimal for certain species that evolve to take advantage of them. As humans though, we are concerned with what is optimal for us. This is, almost by definition, the climate that has prevailed for the last several centuries. This is not because humans could not live, and perhaps thrive, under a different climate regime, but because our whole civilization with its attendant infrastructure of cities, roads, farms, etc. has evolved to be as well adapted as possible to the current climate. While Lindzen may be correct that there is not an optimal climate for the Earth (though the bounds of Mars and Venus should make us grateful for the one we have), there is certainly an optimal climate for our civilization as it stands today.
6. Lindzen’s comparison of the validity of warming forecasts for the year 2040 with the weatherman’s forecast for next week is very misleading. A weather forecast focuses on predicting the exact state of the atmosphere at a given time (e.g., thunderstorms in the afternoon a week from now). Such forecasts depend primarily on knowing the exact current state of the atmosphere, the physical laws governing atmospheric behavior, and how the atmosphere’s inherent internal chaotic behavior gradually limits predictability and alters the evolving weather patterns (e.g., delaying a storm by a day, or shifting its path 50 miles to the north). By contrast, projecting the likely average state of the climate (e.g., the change in typical wintertime temperature) ahead to 2040 depends most on external factors such as the concentrations of greenhouse gases in the atmosphere, which in turn depends mainly on how society chooses to derive energy. A comparable example is the difference between being able to predict the exact value of the GDP on a given day (something determined largely by unpredictable day-to-day news) and projecting the average increase in the GDP over three decades (plausible estimates of which can be made using scenarios of long-term economic growth and ongoing innovation). 

Lindzen’s third paragraph: “A warmer climate could prove to be more beneficial than the one we have now. Much of the alarm over climate change is based on ignorance of what is normal for weather and climate. There is no evidence, for instance, that extreme weather events are increasing in any systematic way, according to scientists at the U.S. National Hurricane Center, the World Meteorological Organization and the Intergovernmental Panel on Climate Change (which released the second part of this year’s report earlier this month). Indeed, meteorological theory holds that, outside the tropics, weather in a warming world should be less variable, which might be a good thing.”

7. Many studies have looked at the likely impacts of a warmer climate, and it is very hard to find significant beneficial influences. For example, while some of those in colder regions will pay less for winter heating, many people will need more air-conditioning, and this will not only be expensive, but will also often require extensive refitting of structures to install air conditioners and to make buildings air tight. More fundamentally, however, the amount and rapid rate of warming will greatly disturb plant and animal species, forcing many to extinction as their natural habitats disappear. Species that already live on the tops of mountains or in the Polar Regions (such as the polar bear) will be unable to migrate upward or poleward into cooler habitats and so risk extinction. Moreover, ecologists are finding that communities of species do not migrate together in response to warming, meaning the delicate balances between predator and prey stand to be substantially disrupted by global warming. And just because those further inland may benefit by becoming closer to the shoreline does not counterbalance the need there will be to protect or abandon and relocate coastal communities. Lindzen’s suggestion of a more beneficial climate is totally unsupported.
8. Lindzen’s statements about variability and extremes perhaps diminishing rather casually excludes the tropics, neglecting the indications that tropical cyclones and storms in general are going to become, and perhaps are already becoming, more intense. Quite simply, warmer temperatures evaporate more water and all indications are that this will lead to greater downpours (something that already appears to be happening in most continental areas). In mid-latitudes, the most violent weather occurs when cold polar air and warm tropical air meet, which often creates strong frontal storms and tornados. As the world warms, the locations of these interactions will shift in space and time, bringing more severe conditions to some regions and less extreme conditions to others. As North America is the only broad continent that stretches from high to low latitudes without an east-west mountain chain, the intersections of cold and hot air masses will continue to occur over the U.S. and Canada­ meaning severe weather will continue and will likely intensify as warming occurs. This past winter’s unusually heavy snowstorms in Colorado did not happen because the region was colder than normal, but because it was warmer than usual. This meant that the intersection of the cold and hot air masses occurred further north than is typical, dumping heavy, wet snow over Colorado. And the very high amounts of snow in northern New York occurred because the Great Lakes were warmer than normal and so did not freeze over, allowing water to evaporate and fall as snow over northern New York.

Lindzen’s fourth paragraph: “In many other respects, the ill effects of warming are overblown. Sea levels, for example, have been increasing since the end of the last ice age. When you look at recent centuries in perspective, ignoring short-term fluctuations, the rate of sea-level rise has been relatively uniform (less than a couple of millimeters a year). There’s even some evidence that the rate was higher in the first half of the twentieth century than in the second half. Overall, the risk of sea-level rise from global warming is less at almost any given location than that from other causes, such as tectonic motions of the earth’s surface.”

9. Since the continental ice sheets of the last ice age melted over 6,000 years ago, net sea level rise has been quite small. While there have been some variations, the locations of various islands, communities, and even the Roman baths built at sea level indicate a small net change. But looking to the distant past is not how to estimate future change. Over the past decade, the rate of sea level rise has increased significantly compared to earlier this century, and satellite evidence indicates that the Greenland and West Antarctic Ice Sheets are starting to lose mass. The predictions of sea level rise for the 21st century often quoted from the recent IPCC report sound reassuringly small, but reading all that the IPCC says indicates that they have left off the key terms that can cause large sea level rise. Looking backwards in time, the IPCC techniques for estimating sea level rise can only explain about 60% of the rise observed from 1961-2003 (even before the observed acceleration in the rate of rise of sea level) suggesting that their predictions for the future are likely to be a substantial underestimate. Again, Lindzen should agree to invest his retirement savings in an uninsurable home along the coast to show his faith in his views.

Lindzen’s fifth paragraph: “Many of the most alarming studies rely on long-range predictions using inherently untrustworthy climate models, similar to those that cannot accurately forecast the weather a week from now. Interpretations of these studies rarely consider that the impact of carbon on temperature goes down—­not up­—the more carbon accumulates in the atmosphere. Even if emissions were the sole cause of the recent temperature rise­—a dubious proposition—future increases wouldn’t be as steep as the climb in emissions.”

10. Given Lindzen’s reliance on theoretical analysis for his own research, it is surprising that he calls models “inherently untrustworthy” for they are all based on the fundamental laws and relationships he himself uses. Furthermore, the models are all thoroughly tested by being compared with observed conditions from pole to equator, winter to summer, and over the past to the present. It is true that the model replications of past conditions are not perfect, which is to be expected given the chaotic variations of the climate about its now-changing baseline; however, the ensemble of model simulations has been tested against previously observed perturbations to climate (such as the response to volcanic eruptions) and overall they correspond well with what is observed to occur.
11. While the enhancing effect of the increasing CO2 concentration on the greenhouse effect is logarithmic (i.e., increasing less than linearly), the increase in emissions over much of the 21st century is projected to be exponential (i.e., increasing more rapidly than linearly). In addition, the ability of biomass and oceans to take up some of the emitted CO2 is decreasing, which will further amplify the warming influence. Further, the share of the warming influence of CO2 being offset by aerosols will be decreasing because their lifetime in the atmosphere is small (10 days or so) whereas the increase in CO2 will persist for many centuries. But, Lindzen is right that CO2 is not the only influence­—the nitrous oxide and halocarbon influences caused by human activities are long lasting and are also increasing.

Lindzen’s sixth paragraph: “Indeed, one overlooked mystery is why temperatures are not already higher. Various models predict that a doubling of CO2 in the atmosphere will raise the world’s average temperature by as little as 1.5 degrees Celsius or as much as 4.5 degrees. The important thing about doubled CO2 (or any other greenhouse gas) is its “forcing”­ its contribution to warming. At present, the greenhouse forcing is already about three-quarters of what one would get from a doubling of CO2. But average temperatures rose only about 0.6 degrees since the beginning of the industrial era, and the change hasn’t been uniform­—warming has largely occurred during the periods from 1919 to 1940 and from 1976 to 1998, with cooling in between. Researchers have been unable to explain this discrepancy.”

12. Lindzen understates the warming that has been observed—­it is now generally agreed to be roughly 0.8ºC rather than 0.6ºC. He also fails to indicate that: (1) some of the warming is being offset by sulfate aerosols that are also due to human activities, and (2) given the large heat capacity of the ocean, the realized warming lags the equilibrium warming that he calculates by several decades. Because of the first of these reasons, were we to abruptly halt all emissions now, the sulfate aerosols would rapidly be removed from the atmosphere by precipitation whereas the CO2 concentration would remain elevated, and so there would be a significant further warming influence just as a result of past emissions; this warming would lead to the quite significant global warming that Lindzen mentions. So, the reasons that the warming is not now as much as he suggests are quite clearly understood.
13. This paragraph seems to ignore the substantial body of research on this issue over the past decade. Quite clearly, the observed climate is the result of responses to all climate forcings, both natural and human-induced. Studies very clearly indicate that when all of these factors are included, there is a quite good understanding of why the temperature variations of the 20th century occurred as they did. Early in the century, changes in solar (warming) and volcanic (weaker cooling) influences apparently led to some warming; during mid-century, the cooling influences of increasing sulfur dioxide emissions (which are chemically transformed into sulfates that tend to cool the planet) exceeded the warming influences of CO2 and other greenhouse gases; and then during the last third of the century, the warming influence from the build-up of CO2 and other greenhouse gases became dominant, especially because SO2 emissions in many areas were being reduced. Within the bands of natural variability, the model simulations quite reasonably reproduce the broad observed variations of the 20th century. Saying that “researchers have been unable to explain this discrepancy” is thus counter to the collective studies of the international scientific community.

Lindzen’s seventh paragraph: “Modelers claim to have simulated the warming and cooling that occurred before 1976 by choosing among various guesses as to what effect poorly observed volcanoes and unmeasured output from the sun have had. These factors, they claim, don’t explain the warming of about 0.4 degrees C between 1976 and 1998. Climate modelers assume the cause must be greenhouse-gas emissions because they have no other explanation. This is a poor substitute for evidence, and simulation hardly constitutes explanation. Ten years ago climate modelers also couldn’t account for the warming that occurred from about 1050 to 1300. They tried to expunge the medieval warm period from the observational record­—an effort that is now generally discredited. The models have also severely underestimated short-term variability El Niño and the Intraseasonal Oscillation. Such phenomena illustrate the ability of the complex and turbulent climate system to vary significantly with no external cause whatever, and to do so over many years, even centuries.”

14. As explained in the comment on the preceding paragraph, the temperature variations over the 20th century have been quite well explained. Indeed, it is true that the solar and volcanic influences are the most poorly estimated, especially early in the century­and it is also true that the observations of global average temperature are least well established during this period. As a result, it is not surprising that the fit between models and measurements during the first half of the 20th century is not perfect. The fact that the climate system can vary internally without external forcing is no reason to suspect that it does not also respond to external forcings, such as the strong response to increasing greenhouse gas concentrations that has occurred in the latter half of the 20th century.
15. Saying that greenhouse gases are given as the reason for recent warming simply because there are no other explanations ignores the mountain of evidence that implicates CO2 and other greenhouse gases instead of natural factors.  Most significant is the cooling of the stratosphere that has accompanied the recent warming of the troposphere and surface, a typical ‘fingerprint’ of the effect of greenhouse gases. Given the complexity of the climate system, the case is necessarily circumstantial, but Lindzen’s argument is like saying there is no viable suspect in a crime when the suspect is caught with the gun, gunpowder residue on his hands, the victim’s wallet in his pocket, and a smirk on his face.
16. Lindzen’s complaint about the supposed ‘cover-up’ of the Medieval Warm Period essentially amounts to a complaint against improved data and better information. Until recently, most of the temperature records came from the European region. Adding data from around the world, however, indicates that the Medieval Warm Period was mainly a regional phenomenon, with warming in one region offsetting cooling in other regions, leaving little change in the average global temperature. By contrast, at present virtually the whole world is warming.
17. Lindzen, who has been a strong supporter of the Bush Administration’s effort to make the science seem uncertain, complains about model shortcomings. At the same time, however, the US Climate Change Science Program, which is supposed to be addressing these uncertainties, has been cutting support for research—­and doing so dramatically. For quite a number of years, the actual dollar support was held about level (so decreasing at the rate of inflation), but more recently the absolute dollar amount has been dropping. As a result, the purchasing power of the global change research budget is down more than a third­—to a level that is equivalent to about 1.5 cents per day per person in the US. So, the Administration policy, egged on by Lindzen citing supposed uncertainties, is asking for greater certainty (actually, they mean higher confidence), but providing less and less funds for doing the necessary research. [Note that the budget totals cited by the Administration do not show such drastic cutbacks because activities not previously counted as part of the funding are now being counted, thus covering over the significant decline in research funding that has occurred.]

Lindzen’s eighth paragraph: “Is there any point in pretending that CO2 increases will be catastrophic? Or could they be modest and on balance beneficial? India has warmed during the second half of the 20th century, and agricultural output has increased greatly. Infectious diseases like malaria are a matter not so much of temperature as poverty and public health policies (like eliminating DDT). Exposure to cold is generally found to be both more dangerous and less comfortable.”

18. Agricultural output in India increased because of the Green Revolution in India—­better seeds, fertilizer, and modern farm equipment. Over the past 50 years, technological improvements have more than offset environmental factors. However, this is very unlikely to continue to be the case, especially because future warming will greatly exceed past warming. Indeed, poverty contributes to disease; climate change makes it much harder to overcome poverty, especially when very powerful storms, such as Hurricane Mitch, wipe out 20 years of progress. Many see rapid climate change acting to amplify existing stresses on social and environmental systems, worsening their impacts, especially for the poor and vulnerable who are least able to cope. That disease will increase elsewhere will also affect us here in the U.S. Because we live in a global marketplace, what happens elsewhere will have economic impacts here and elsewhere. In addition, the intensification of environmental stresses caused by climate change will tend to increase social unrest, political instability and conflict, and the likelihood that those in stressed regions will push to emigrate to developed nations such as the U.S., thus affecting our geostrategic interests and national security. In addition, avoiding the cold is generally less expensive and less difficult than avoiding the heat, especially given that absolute humidity rises exponentially with temperature (and so the discomfort index increases very rapidly).

Lindzen’s ninth paragraph: “Moreover, actions taken thus far to reduce emissions have already had negative consequences without improving our ability to adapt to climate change. An emphasis on ethanol, for instance, has led to angry protests against corn-price increases in Mexico, and forest clearing and habitat destruction in Southeast Asia. Carbon caps are likely to lead to increased prices, as well as corruption associated with permit trading. (Enron was a leading lobbyist for Kyoto because it had hoped to capitalize on emissions trading.) The alleged solutions have more potential for catastrophe than the putative problem. The conclusion of the late climate scientist Roger Revelle­—Al Gore’s supposed mentor—­is worth pondering: the evidence for global warming thus far doesn’t warrant any action unless it is justifiable on grounds that have nothing to do with climate.”

19. First, Lindzen leaves out all the benefits of simply using energy more efficiently, so saving money while also benefiting the environment. For example, Californians, as a result of astute actions and policies, use only half as much electricity per person as those in the rest of the country, saving the typical household about a thousand dollars a year. The Pew Center on Global Climate Change cites experiences of a number of companies that have both cut emissions and cut costs. Renewable wind power in Texas is providing electricity to experimental hybrid-electric vehicles that reduces the cost of transportation while also reducing the need for oil imports. Indeed, corn is not the optimal basis for providing all the ethanol fuel we will need, but, as the President says, biofuels are needed to reduce our addiction to oil and to slow climate change—­and the emerging biofuels market is spurring major investments in using biomass other than corn to make ethanol. Second, inventing concerns about possible corruption in some aspects of carbon permit trading without mentioning the financing of terrorism that occurs through the global petroleum markets is really ignoring a much bigger concern. Third, experience with efforts to limit SO2 emissions indicates that the cap and trade approach has greatly reduced the costs of implementing control measures.
20. Then there is the clever touch of quoting from Roger Revelle, and using this to create a tie to Al Gore. Given that Revelle died in 1991, this quote about there not yet being sufficient evidence to act on climate change dates to a time well before the global average surface temperature provided evidence of human-induced warming taking over from natural variations, well before evidence that glaciers and ice sheets were melting, well before observations indicated that the ranges of large numbers of species are shifting poleward, and on and on. Were Revelle alive today, he would surely be very concerned about the “great geophysical experiment” that he identified as occurring about 50 years ago.

In conclusion, Lindzen’s op-ed is deceptive and misleading, trying to blur and distort the very clear international scientific consensus that climate change is real, is primarily due to human influences, is already causing important impacts on the environment, and that future changes and impacts will be much more serious. The reason to be gloomy is that political efforts to deal with this increasingly serious issue have been so limited in the 40 years since 1965 when Revelle, as chair of a panel of the President’s Science Advisory Council, indicated to the president that human-induced climate change was a real issue deserving of attention.

*In addition to his activities since 2002 with the Climate Institute, Dr. MacCracken served on the integration team for the Arctic Climate Impact Assessment from 2002-2004. Dr. MacCracken is also near completing a 4-year term (2003-2007) as president of the International Association of Meteorology and Atmospheric Sciences (IAMAS), members of which are the national academies of science or their equivalent in about 50 nations. As president of IAMAS, Dr. MacCracken also serves on the executive committees of International Union of Geodesy and Geophysics (IUGG) and of the Scientific Committee for Oceanic Research (SCOR). 

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