Climate change is unequivocal

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R K Pachauri, Chairman, Intergovernmental Panel on Climate Change (IPCC)

Special reports published by The Intergovernmental Panel on Climate Change (IPCC) provide a comprehensive assessment of knowledge on all aspects of climate change. These include advances in scientific understanding related to climate change and major findings from working groups. Together, these reports have, and are having, a major impact on public opinion and awareness among world leaders. The IPCC’s most recent Fourth Assessment Report sets out to integrate and compact this wealth of information into a readable and concise document explicitly targeted at policymakers.

The Intergovernmental Panel on Climate Change (IPCC) has been in existence since 1988 having been established by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP). During this period the Panel has not only brought out four assessment reports, which present a comprehensive assessment of knowledge on all aspects of climate change, but has also produced several special reports dealing with specific issues related to climate change. As part of the Fourth Assessment Report (AR4), three volumes representing the contributions of Working Group I, II, and III have already been completed and released.

The Synthesis Report bringing together the major findings of the three working groups was released in November 2007. The AR4 has incorporated several advances in scientific knowledge related to climate change. This has had a major impact on public opinion and awareness among world leaders on knowledge related to observed climate change in recent decades as well as projections for the future.

OBSERVED IMPACTS

One major finding of the AR4 has been the fact that climate change is now unequivocal and the human influence on the Earth’s climate is now very well established. The average temperature increase across the globe during the 20th century has been around 0.74°C and sea level rise around 17cm. These changes have been accompanied by changes in precipitation as well, including an increase in precipitation in the higher latitudes and a decline in the lower latitudes as well as the Mediterranean region. However, these changes have also been accompanied by an increase in the frequency and intensity of extreme precipitation events.

While any single event that occurs cannot be linked to human induced climate change, the pattern observed across the globe provides abundant evidence of this trend. It is also observed that floods and droughts are increasing in frequency and intensity and this trend is likely to continue.

FUTURE TRENDS

Projections of temperature increase in the 21st century have been made on the basis of established and plausible scenarios of the future. At the lower end of these scenarios, the best estimate of temperature increase by the end of the 21st century is placed at 1.8°C and at the upper end of the scenarios, the best estimate is approximately 4°C. These projections are of course based on the assumption of no specific action towards mitigation of emissions of greenhouse gases (GHGs).

UNEQUAL IMPACTS

The impacts of climate change vary across regions and communities. In general, these are most severe in those regions which display high vulnerability on account of a number of factors including poverty. For instance, during the 20th century, glaciers and ice caps have experienced widespread mass losses, which are likely to have major consequences for water supply in several areas of the world. In fact, new data clearly confirm that losses from the ice sheets have contributed to sea level rise over the period 1993-2003.

ECOSYSTEM DISRUPTION

Other observed impacts of climate change include more intense and longer droughts, widespread change in extreme temperatures as well as changes in biodiversity. In general, it was assessed that climate change will reduce biodiversity and perturb the functioning of most ecosystems and therefore compromise on the services that they currently provide. Of the species that were assessed it was found that 20 to 30 per cent of plant and animal species would be at risk of extinction if increases in global annual temperatures exceed 1.5 to 2.5°C. Some ecosystems are particularly vulnerable, such as coral reefs and marine shell organisms.

FOOD INSECURITY

Another major area of serious impacts is in the field of agricultural production. Malnutrition, for instance, would be further exacerbated by the reduced length of the growth seasons in the Sahelian region of Africa. In some countries, yields from agriculture could be reduced by up to 50 per cent by 2020. With the growing scarcity of water in different regions of the world, it was also assessed that 75 to 250 million people would be exposed to increased water stress in 2020 in Africa alone. In the case of sub- tropical and tropical regions, a temperature increase above 1.5 to 2.5° C is expected to lead to a decline in agricultural productivity of crops such as maize and wheat. In fact, there is growing evidence in South Asia, for instance, that the wheat crop is already being affected adversely by climate change.

COASTAL FLOODING

Another serious impact of climate change is seen most prominently in the Asian region where the megadeltas such as Kolkata, Dhaka, and Shanghai are at risk of coastal flooding and negative impacts. There are other cities in the world, also located in coastal areas, with high density populations at high risk of coastal flooding and other impacts with the prospect of high sea levels.

COST EFFECTIVE CLIMATE MITIGATION

While an understanding of these impacts of climate change provides a rationale for mitigation of GHGs which could help to avoid or postpone some of these impacts, such an approach is strengthened by the relatively low cost and general attractiveness of mitigation measures available around the world. One scenario assessed for the future that would limit temperature increase at equilibrium to 2.0–2.4°C would actually cost the world less than three per cent of the global GDP in 2030. But if such a scenario was to be realised, the level of global emissions will have to peak by 2015 and decline thereafter.

CONCLUSION

Overall, the IPCC’s AR4 has had a major impact on awareness and knowledge on various aspects of climate change across the globe. While climate change represents a growing challenge to human society, there are several other areas where the creation and dissemination of knowledge by specialists and experts, and accepted by the governments and decision makers, may have great merit in these areas of human endeavour as well. Quite apart from the specific knowledge provided by the IPCC, it is the example it sets which merits application perhaps in other important areas where we may be jeopardising the future of living systems on this planet and the welfare of future generations. There is need perhaps for clones of the IPCC in other areas of human activity and public policy.

Author

Dr. Rajendra Kumar Pachauri was elected Chairman of the Intergovernmental Panel on Climate Change (IPCC) in 2002. The IPCC, established by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), is the leading body for the scientific assessment of climate change. Dr. Pachauri has also been the head of TERI, The Energy and Resources Institute, since its establishment in New Delhi 25 years ago. TERI is an Indian institute of excellence working on scientific and technological research and strategic thinking in the fields of energy, environment, forestry, climate change, biotechnology, conservation of natural resources and sustainable development. Dr. Pachauri has taught at various universities in India and the USA, including the School of Forestry and Environmental Studies, Yale University, in 2000. He was Research Fellow at The World Bank, Washington, DC in 1990. He was adviser to the Administrator of the United Nations Development Programme (UNDP) in the fields of energy and sustainable management of natural resources from 1994 till 1999.

To acknowledge his immense contributions to the field of environment, he was awarded the Padma Bhushan by the President of India in January 2001, one of India’s highest civilian awards. Among other awards, he was honored as “Officier De La Légion D’Honneur” by the Government of France in 2006. Along with his colleagues at the IPCC, the organisation’s work was also awarded the 2007 Nobel Peace Prize for its contributions to climate change understanding.

Organisation

The IPCC, established by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), is the leading body for the scientific assessment of climate change. It is also the organisation that jointly won, with Al Gore, the 2007 Nobel Peace Price for its efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change.
The organisation assesses scientific, technical and socioeconomic information relevant for the understanding of climate change, its potential impacts and options for adaptation and mitigation.

Enquiries

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Picture credits: Roof - Maksim Privazov/Fotolia; Flooded town - Binh Duc - UNEP/Still Pictures

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