Climate change: coping with a warming world

Last week the Summary for Policy Makers approved by the member governments of the Intergovernmental Panel on Climate Change (IPCC), which is part of the Third Assessment Report of Working Group?I of the IPCC, was released in a meeting held at Shanghai. This report builds on the previous two assessments of the IPCC and represents the effort of hundreds of experts and scientists from all over the world. In all there were 123 coordinating lead authors, 516 contributing authors, 21 review editors, and about 300 expert reviewers who contributed to the preparation of this report. The contents of the report provide the current state of understanding of the world?s climate system, estimates of future evolution of global climate, and associated uncertainties. The results of this report provide cause for alarm. It is found, for instance, that the global average surface temperature has increased since 1861. Over the 20th century the increase has been 0.6 ? 0.2 ?C. This value is about 0.15 ?C larger than the value estimated by the Second Assessment Report which was completed in 1995 and published in 1996. What is even more alarming is the fact that since 1995 temperatures have been substantially higher in the Northern Hemisphere. It is now reasonably clear that the 1990s was the warmest decade and 1998 the warmest year in the Northern Hemisphere since records have been instrumented and maintained since 1861. Methods of processing past data have been refined substantially in recent years, and on this basis it appears that the increase in temperature in the 20th century is likely to have been largest of any century during the past 1000 years. It is not as though climate change that has taken place and that is likely to take place in the future only involves a linear increase in global surface temperatures. In fact, with the impact of human activities the entire climate system of the earth is being disrupted to the extent that impacts are taking place in very complex ways. For instance, satellite data reveal that in all likelihood decreases of about 10% have taken place in the extent of snow cover since the late 1960s, and further observations show that there has been a reduction of two weeks in annual duration of lake and river ice in the mid and high latitudes of the Northern Hemisphere over the 20th century. Mountain glaciers in the non-polar regions have receded on a widespread basis during the 20th century. This has very serious implications for India. Already, there is direct evidence of the reduction in size and receding of glaciers in the Himalayan range. This would have harmful consequences for surface water flows throughout northern India, and would affect the livelihood of hundreds of millions of people and the survival of every form of life. The report also highlights changes that may have taken place in the established patterns of precipitation. The likelihood is that rainfall has increased by 0.2% to 0.3% per decade over the tropical land areas within a belt of 10 ?N to 10 ?S. At the same time, it is likely that rainfall has decreased over much of the Northern Hemisphere, in subtropical land areas, i.e., between 10 ?S to 30 ?N by about 0.3% per decade. For India, the assessment for the subtropical areas is of relevance, because this also tallies with anecdotal evidence and recent records of reduced rainfall over the subcontinent. The main importance of the Report of Working Group-I of the IPCC is not so much in the assessment of what has happened but, perhaps, in what is likely to happen throughout the 21st century. It is inevitable that with the current level of consumption of fossil fuels worldwide that concentration of carbon dioxide in the earth?s atmosphere will continue to increase reaching anything above double the concentration levels that existed at the start of the industrial revolution in the middle of the 19th century. There are six major gases identified as greenhouse gases (GHGs), the high concentration levels of which result in global warming and climate change. However, the most prominent of these gases is carbon dioxide, which is largely the result of combustion of fossil fuels. The world, therefore, has to shift to much lower levels of consumption of fuels in the aggregate and towards low carbon intensity fuels specifically. For instance, natural gas per unit of heat produces lower carbon dioxide emissions than oil which in turn is less carbon intensive than coal. Cumulative emissions of carbon dioxide produced by the developed countries have been largely responsible for creating high levels of concentration of this gas in the earth?s atmosphere. The Framework Convention on Climate Change (FCCC), agreed during the Rio Summit of 1992, clearly highlighted the common but differentiated responsibilities of different countries to reduce the concentration of greenhouse gases in the earth?s atmosphere. The Kyoto Protocol which was agreed during the 3rd Conference of the Parties to the FCCC held in Kyoto in November 1997 laid down specific emission reduction targets for the developed countries. Unfortunately, this Protocol has not yet been ratified, and some nations, most notably the US, have shown no willingness to ratify it unless key developing countries ?participate meaningfully?. This, of course, goes against the basic principles of the FCCC. The result of inaction would be further disturbance in the earth?s climate system even while those nations which have the economic and technological strength and the overwhelming responsibility for taking action are reluctant to do so. It is hoped that the release of the Third Assessment Report of the IPCC will bring about greater efforts on the part of the international community and the governments of the developed countries to reduce their excessive use of energy as well as move towards greater use of renewable forms of energy, so that planet earth is not threatened by massive changes of climate that would have serious implications for all forms of life.