The recent media revelation that the earths average atmospheric temperature has hardly budged for the last 17 years has been known to, and debated within, the global scientific community for some time. This pause, which can no longer be treated as an outlier does not yet place the earths average temperature outside the range of uncertainty of forecasts from some 70 climate models developed by researchers around the world, but is certainly skating close to the edge. Moreover, none of the models predicted such an actual long pause in rise of the earths average temperature.
The Inter-Governmental Panel on Climate Change (IPCC), a network of scientists from different countries nominated by their governments, and tasked by the UN with preparing consensus reports on the earths climate, technology options, costs of response measures, and now, even the ethical basis of burden-sharing among countries, is to shortly discuss this finding. At stake is the future evolution of negotiations towards an international treaty to comprehensively address climate change, hoped to be concluded by 2015 and widely expected to be the mother of all economic treaties yet since nothing less than the future rights of countries to use commercially proven energy is at stake. However, this is also an existential issue for the IPCC itself since it must be unambiguously seen to apply the stringent tenets of the scientific method in dealing with this result if it is to retain and enhance its own credibility among both scientists and voters from different countries whose intellectual and political support respectively are crucial to successful negotiation of the new treaty.
Several explanations have been offered to explain this 17 year hiatus. Some scientists have pointed to stronger than expected La Nina ocean events during this period. However, this begs the question why, at least, those models which couple the atmospheric and oceanic circulation systems did not anticipate the strength of the La Nina events. Another suggested explanation is that during these 17 years there were more frequent volcanic eruptions than on average, spewing sulphur dioxide into the atmosphere, which is known to reflect solar radiation back into space. However, the statistical distribution of volcanic eruptions is well-known, and the climate modelers should have evaluated the odds of bunching together of volcanic eruptions, and adjusted their range of uncertainty. Yet another is that the sun is currently undergoing a quiescent period of solar activity, and the earths heating would resume once the sun reverts to a more active phase. However, once again, the fact that the sun would be relatively quiet over this period should have been factored in by the climate modelers.
The explanation, that to my mind is the most plausible, is as follows: The direct warming effect of carbon dioxide which results from burning fossil fuels, and other man-made greenhouse gases (GHGs) such as methane is actually quite modest. However, water vapour is a strong GHG in itself, and accounts for the natural greenhouse effect which is what, after all, gives the earth its hospitable climate. An initial warming due to carbon dioxide and other man-made GHGs would increase evaporation of water from the oceans, and this would, at first blush, increase the initial warming due to man-made GHGs. However, the increased water vapour in the atmosphere may also induce increased cloud cover which reflects solar radiation back into space. The net effect may thus be either increased heating or cooling, and neither is inconsistent with thermodynamics. It is possible that the parameter capturing the positive feedback from water vapour in the atmosphere was incorrectly estimated by earlier researchers, and in a startling demonstration of groupthink most modelers adopted these incorrect estimates. The result is forecasts of the earths future temperature that are significantly higher than actually recorded. However, this is but one candidate explanation, and the true explanations may lie elsewhere. The problem with all the explanations on offer is that they are ex post, and beg the question of why the modelers did not take them into account before publishing their models forecasts.
What is to be done? First, the IPCC. The scientific method involves not ignoring uncertainty, but in being explicit about it. Climate scientists need to acknowledge that there is a great deal about the mechanisms of the global climate that they do not yet sufficiently understand, and perhaps that they do not yet know what they do not know. The basic physics of climate change is not at dispute, but knowledge about how all the complex factors influencing the global climate work together is still sketchy. Much further research is called for, and in particular, the future research must involve partnerships among institutions between developed and developing countries in order to enhance its credibility. As of now, far too much of the published climate research originates in developed countries.
Second, about the global climate regime being negotiated. Hitherto, the storyline from several developed countries has been that the sky is falling, the sky is falling!, and that all countries, including the developing world, the mega-states of India and China in particular, must understand that the greater global good lies in saving the world here and now no matter that their development aspirations go unfulfilled, their poor wallow in misery several more generations, and that the developed world stays rich and escapes being held to account for its historical responsibility for the problem. Such an approach has, unsurprisingly, been strongly resisted by the developing world in general, and India and China in particular. A saner approach is now called for. The probable eventual, serious manifestation of man-made climate change, as well as the depletion of fossil fuels, can only be solved by cost effective, reliable renewable energy technologies (and emerging, inherently safer nuclear energy technologies). There are several successful examples of international technology cooperation. An outstanding current example is the ITER project, which aims to develop fusion based nuclear reactors which will rely on (heavy) hydrogen available inexhaustibly in the earths oceans. The commercial application of this technology is several decades away, but a number of countries, India included, are contributing human and material resources to the project after agreeing to share in the resulting IPRs. Cost-effective solar, wind, tidal, biomass, transportation, and energy storage technologies may be similarly developed by international cooperationmost are probably just a decade away from full commercialisation.
In the meanwhile, the existing UN Framework Convention on Climate Change (UNFCCC), itself provides the basis for a new approachthe Precautionary Principlethat in the face of scientific uncertainty countries should take cost-effective steps to address the problem. A number of measures make economic, social, and environmental sense as of nowmost energy efficient appliances and lighting, mass transport, net conferencing, niche applications for renewable energy, less packaging of consumer goods, recycling and reuse of materials, conserving water, vegetarianism. These will bust neither the fisc nor the current account nor household budgets. At the same time they will enhance growth, social progress and environmental conservation.
The author is the director of the earth science and climate change division at TERI