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New evidence of rapid global warmingPosted: 10 Mar 2001
by Jeremy Hamand
The scientific basis for rapid global warming is clearer than ever before, a comprehensive new United Nations report reveals. The new assessment by the Intergovernmental Panel on Climate Change (IPCC), released in three parts between January and March, warns of a "potentially devastating" global warming of 1.4 to 5.8 degrees Celsius over the coming century. This upper forecast is for higher temperatures than an assessment by the same panel five years ago.
Delegates from 99 governments met in Shanghai in January to consider the new evidence contained in the first part of the latest IPCC Report, "Climate Change 2001: The Scientific Basis." They unanimously accepted it.
New analyses of data from tree rings, corals, ice cores and historical records for the northern hemisphere show that the increase in temperature in the 20th century is the largest of any century during the past 1,000 years. Globally, the 1990s were the warmest decade and 1998 the warmest year in the instrumental record since 1861, the scientists found.
Global Atmosphere Watch weather monitoring station at Barrow, Alaska (Credit: World Meteorological Organization)
"The scientific consensus presented in this comprehensive report about human induced climate change should sound alarm bells in every national capital and in every local community, said Klaus Toepfer, Executive Director of UNEP. "We must move ahead boldly with clean energy technologies, and we should start preparing ourselves now for the rising sea levels, changing rain patterns, and other impacts of global warming," he urged.
Key findings of the report include new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities. Since the IPCC�s 1995 Report, confidence in the ability of models to project future climate has increased. There is now a longer and more closely scrutinized temperature record. Reconstructions of climate data for the past 1,000 years, as well as model estimates of natural climate variations, suggest that the observed warming over the past 100 years was unusual and is unlikely to be entirely natural in origin.
In the mid-latitudes and high latitudes of the northern hemisphere, it is very likely that snow cover has decreased by about 10 per cent since the late 1960s, and the annual duration of lake and river ice cover has shortened by about two weeks over the 20th century, the climate scientists agree. In recent decades, there has been about a 40 per cent decline in Arctic sea ice thickness during late summer to early autumn, the researchers found.
In February, the IPCC released a second part of its report analysing how this general warming will affect Africa, Asia, Europe and other regions over the coming decades. While highlighting remaining uncertainties, it details expected changes in weather patterns, water resources, the cycling of the seasons, ecosystems, extreme climate events, and much more. The report suggests that:
- Coral reefs in most regions could be wiped out within 30-50 years by warming oceans as temperatures reach levels at which coral bleaching becomes an annual event.
- Three-quarters of the world's largest mangrove forest, the Sundarbans, in India and Bangladesh, could be inundated by a sea-level rise of 45 cm, putting the Bengal tiger at risk of extinction.
- The Cape Floral Kingdom, in South Africa, which is exceptionally rich in species that occur nowhere else, could be wiped out as a result of temperature changes expected this century.
- Also under threat is the polar ice edge ecosystem that provides habitat for polar bears, walrus, seals and penguins.
- Other species under threat from climate change are forest birds in Tanzania, the mountain gorilla in Africa, the spectacled bear of the Andes, and the quetzal in Central America.
The report shows that the worst impacts will hit developing countries, which have the least capacity to adapt. Africa is "highly vulnerable" to climate change affecting water resources, food production, the expansion of deserts and causing more frequent outbreaks of diseases of cholera.
The report lists a string of small island states in the Pacific and Indian oceans and the Caribbean, threatened by climate change and where unique cultural and conservation sites have already been destroyed. Glaciers in tropical regions such as the Himalayas are particularly threatened by climate change, according to the IPCC. Himalayan glaciers are the major source of water for the rivers Ganges and Indus on which 500 million people, just under one-tenth of the world's population, depend.
Industrialized nations can also expect significant impacts. The United States, Canada and Australia could well see an expansion in diseases such as malaria, tick-borne Lyme disease, Ross River virus and Murray Valley encephalitis respectively. Many regions of the world will experience heat waves that will compound the effects on health in polluted cities. Much of Europe will have to endure increased hazards of floods.
Burning forests such as this one in Brazil release heat-trapping carbon dioxide into the atmosphere and destroy the trees\' potential to absorb existing carbon dioxide. (Credit: University Corporation for Atmospheric Research (UCAR))
"Climate change is a stress that will be superimposed over expected population and other environmental stresses," said Professor G O P Obasi, Secretary-General of the World Meteorological Organization (WMO), which, together with UNEP, launched the IPCC in 1988. "Life as we know it today on the planet will be forced to respond to the shift to a warmer world. We have to use mitigation and adaptation strategies to face the changes while not forgetting to improve our knowledge basis. Every natural and socio-economic system appears to be vulnerable to climate change. However, it is the least developed countries that are the most vulnerable."
The last of three major reports by the IPCC was adopted by climate change experts and officials from some 100 governments meeting in Accra, Ghana from February 28 to March 3. They believe that global warming can be conquered, but development paths leading to low greenhouse gas emissions "depend on a wide range of policy choices and require major policy changes in areas other than climate change."
Technological options for emission reduction include improved efficiency of end use devices and energy conversion technologies, shift to low carbon and renewable biomass fuels, zero emissions technologies, improved energy management, reduction of industrial byproduct and process gas emissions, and carbon removal and storage, the IPCC report says.
In the period 2010 to 2020, the scientists conclude, hundreds of technologies and practices for more efficient energy use in buildings, transportation and manufacturing can deliver over half the total potential emission reductions.
The three IPCC reports set the stage for the next round of international climate negotiations for implementation of the Kyoto Protocol set to start this July in Bonn.
The complete three-volume report, with downloadable summaries, has now been published by IPCC.
Visit UNEP's Global Resource Information Database at Arendal, Norway, for useful climate graphs.
World Meteorological Organisation (WMO), Geneva.
Explore official documents about the climate talks at the UN Framework Convention on Climate Change.
Jeremy Hamand is a freelance journalist and former Associate Editor of People & the Planet.