MIT professor Kerry Emanuel’s February 15 op-ed in the Boston Globe, “Climate Changes Are Proven Fact,” has many inaccuracies, and in my view it is not a positive contribution to the global warming debate.
I have noted below Emanuel’s most important assertions, followed by my responses to correct the record.
Emanuel argues: “compelling strands of scientific evidence … have led almost all climate scientists to conclude that mankind is altering climate in potentially dangerous ways.”
A high percentage of meteorologists and/or climate scientists do not agree that the climate changes we have seen are mostly manmade. Thousands of us think the larger part of the climate changes we have observed over the last century are of natural origin. I believe most of the changes that have been observed are due to multi-decadal and multi-century changes in deep global ocean currents. Such changes have yet to be properly incorporated into the global models or into most climate modelers’ thinking.
More than 31,000 American scientists have recently signed a petition advising the United States not to sign any fossil-fuel reduction treaty.
Many scientists believe a slightly warmer world would be, in general, more beneficial for humanity. The small changes in climate we have seen so far and the changes we will likely see in the coming decades are not potentially dangerous. It has been noted that vegetation growth is enhanced by higher CO2 levels.
Emanuel states: “the surface temperature of the Earth is roughly 60 F higher than it would otherwise be thanks to a few greenhouse gasses.”
The globe’s greenhouse gas-induced higher temperatures are due almost exclusively to water vapor (the overwhelming greenhouse gas), and not much at all due to CO2 and methane. It is the variation of atmospheric water vapor (particularly in the upper troposphere) that is of dominant importance to the greenhouse gas warming question.
It is likely that increases in CO2 and other minor greenhouse gases will lead to small reductions in upper tropospheric water vapor, which will bring about greater loss of infrared radiation energy flux to space. Increases in CO2 and lesser greenhouse gases should (due to their influence on upper level water vapor) lead to little global temperature increase.
This appears to be occurring now. During the last decade and a half, while CO2 amounts have risen there has been an increased (not decreased) infrared radiation flux to space. Little or no global warming has occurred in the last decade.
Emanuel claims: “in the absence of any feedbacks except for temperature itself, doubling carbon dioxide would increase the global average surface temperature by about 1.8 F.”
You can’t eliminate water vapor and cloud feedback and consider only temperature feedback and expect to have a realistic explanation of CO2’s future influence on global temperature. Water vapor and cloud feedback changes can negate most or all the lesser greenhouse gas influences on global temperature.
Emanuel asserts: “The rate of rise of surface temperature is consistent with predictions of human-caused global warming that date back to the 19th century and is larger than any natural change we have been able to discern for at least the past 1,000 years.”
This is a pure ‘off-the-wall’ assertion the global warmers want to believe in because they do not want to consider other causes of climate change which would negate their human-induced warming hypothesis. The Medieval warm period and the early Holocene warm period are believed to have been warmer than today’s temperatures. Some natural processes brought about these changes. Why couldn’t these same natural processes be acting today?
Emanuel observes: “current models predict that a doubling of carbon dioxide should result in global mean temperature increases of anywhere from 2.5 to 7.5 F.”
All the global General Circulation Models (GCMs) which predict future global temperature change for a doubling of CO2 are badly flawed. They do not realistically handle the changes in upper tropospheric water vapor and cloudiness. Model global warming estimates for a doubling of CO2 are thought by thousands of us to be many times larger than what will likely occur.
The GCMs are not yet simulating the fundamental influence of the multi-decadal and multi-century scale variations of the ocean’s deep circulation patterns.
It should be noted that the GCMs have failed to account for the weak global cooling of the last decade. It is also important to note the GCM groups do not make official shorter-range global temperature forecasts of 1 to 10 years which could accurately be verified. If they won’t do this, why should we believe their forecasts at 50-100 years? Any experienced meteorologist or climate scientist who actually believes a long range climate model is living in a dream world.
Emanuel agues models “represent our best efforts to objectively predict climate; everything else is mere opinion and speculation.”
As discussed above, the global GCM climate models are likely our worst, not best, guide to the future. The physics and numerical coding within the global climate models will never be able to replicate the complex global atmosphere/ocean environment and its continuing changes.
Our only reliable guide to the future climate rests with the study of past observations of the globe together with judicious reasoning regarding the primary processes which have influenced climate change in the past.
Emanuel claims: “That they are uncertain cuts both ways; things might not turn out as badly as the models now suggest, but with equal probability, they could turn out worse.”
This is simply ridiculous. The global models have grossly erred on the side of too much global warming though their unrealistic assumptions of a positive water vapor feedback loop and their lack of consideration of deep ocean currents. There is absolutely no way the models could have underestimated the role of human-induced CO2 increases on global warming.
Emanuel asserts: “We do not have the luxury of waiting for scientific certainty, which will never come, nor does it do anyone any good to assassinate science, the messenger.”
Living in an academic ivory tower relieves Emanuel of having to face up to the hard economic and social realities of reducing fossil fuel usage. Emanuel fails to acknowledge the substantially higher costs of renewable energy and the resulting significant decline of the global population’s standard of living which large fossil fuel reductions would bring. These changes would increase poverty and starvation in Third World countries.
In addition, he fails to consider how little the environment would really improve if such human sacrifices were made.
We should all call out faulty science wherever we see it, including the blind belief (without any evidence beyond the faulty models) that humans are largely responsible for climate change.
Emanuel recommends: “We might begin by mustering the courage to confront the problem of climate change in an honest and open way.”
Emanuel should follow his own advice. His op-ed is one-sided and less than an honest and fair representation of the global warming controversy.
William Gray ([email protected]) is professor emeritus of atmospheric science at Colorado State University.