New Evidence of Rapid Global Warming
Leading climate change scientists and government officials from around the world have finalised a major report confirming the strengthening evidence for humanity's influence on the global climate. The new assessment by the Intergovernmental Panel on Climate Change (IPCC) projects a potentially devastating global warming of 1.4-5.8°C over the coming century.
Some of the report's main findings are:
- There is new and stronger evidence that most of the warming observed over the last 50 years was caused by human activities.
- Globally it is very likely that the 1990s were the warmest decade, and 1998 the warmest year, in the instrumental record, since 1861. Also, the increase in temperature in the 20th century is likely to have been the largest of any century during the past 1000 years.
- In the mid- and high-latitudes of the northern hemisphere it is very likely that snow cover has decreased by about 10% since the late 1960s, and the annual duration of lake- and river-ice cover has shortened by about 2 weeks over the 20th century.
- It is likely that there has been about a 40% decline in Arctic sea-ice thickness during late summer to early autumn in recent decades.
- Since 1750, the atmospheric concentration of carbon dioxide has increased by 31% from 280 parts per million (ppm) to about 367 ppm today. The present CO2 concentration has not been exceeded during the past 420,000 years and probably not during the past 20 million years.
- Sea-levels are projected to rise by 0.09 to 0.88 metres from 1990 to 2100.
Over 150 delegates from about 100 governments participated in the working group meeting. The full report is over 1000 pages, has been 3 years in production, and was written by 123 lead authors, assisted by more than 516 contributing authors.
Second IPCC Report
The second IPCC report shows that global warming will have far reaching impacts on natural and human systems. This report focuses on the effects of climate change on water resources, agriculture, human settlements and natural ecosystems.
NZ Effects
Apart from rising temperatures, the report says the greatest effect of climate change on NZ is likely to be on water resources. This arises from the possibility of increasing rainfall in the west and decreases in the east, more frequent heavy rainfall events, and a tendency for conditions to become more El Niño-like.
The report explains that in some areas the impacts may not be all bad initially, as agricultural productivity in temperate regions may be improved by a warmer climate. But changes in rainfall patterns and extreme climate events such as droughts, heat waves and floods are also predicted to increase over the 21st century, reducing the potentially beneficial effects of climate change.
The Rest of the World
The countries that will be hit hardest by climate change are the poorest nations with the least capacity to adapt, while developed nations in temperate regions may even be able to improve their productivity, at least in the short to medium term. This will have major consequences on the world's economy. The draft Geneva report gave a regional breakdown of what may lie ahead for the rest of the world:
- Africa: Grain yields are expected to decrease, and less water will be available. Desertification will be worsened by reductions in average annual rainfall, especially in Southern, North and West Africa. Coastal settlements in Nigeria, Senegal, Gambia, Egypt, and along the East-Southern African coast will be hit by rising sea levels and coastal erosion
- Asia: High temperatures, drought, floods and soil degradation will probably lessen food production in arid and tropical parts of Asia. Northern areas may see an increase in productivity. Rises in the sea level and more intense tropical cyclones are likely to displace tens of millions of people in low-lying coastal areas of temperate and tropical Asia.
- Europe: Southern Europe will become more prone to drought. In other areas, flood hazards will increase. Half of Alpine glaciers could disappear by the end of the 21st century. Heat waves may change traditional summer tourist destinations and less reliable snow conditions may hurt winter tourism. Agricultural productivity may increase in northern Europe but decrease in southern Europe.
- Latin America: Floods and droughts will become more frequent. Yields of important crops will very likely decrease in many parts of Latin America. Subsistence farming in north-eastern Brazil could be threatened. Exposure to diseases such as malaria and cholera may increase.
- North America: Food production could benefit from modest warming, but there will be strong regional effects including declines in Canada's Prairies and the US Great Plains. Rising sea levels could increase coastal erosion, flooding and lead to more storm surges, particularly in Florida and the Atlantic coast. Diseases like malaria, dengue fever and lyme disease may expand their ranges in North America.
- Polar: Climate change in polar regions is expected to be among the largest anywhere. Already, the extent and thickness of Arctic sea ice have decreased, permafrost has thawed and the distribution and abundance of species has been affected. The trends may continue even long after greenhouse gas emissions are stabilised, and cause irreversible impact on ice sheets, global ocean circulation and sea levels.
Contact for Enquiries
The Ministry of Agriculture and Forestry
Pastoral House
25 The Terrace
PO Box 2526, Wellington
Tel: 0800 00 83 33
Fax: +64 4 894 0720
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