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On Changing Climates

Because of the expansion of human economic activities, the amount of greenhouse gases, carbon dioxide, methane, nitrous oxide, HFCs, PFCs, SF6, and etc. have been increasing. The greenhouse effect is intensifying, causing global warming, a rise in the sea level, unbalancing the ecosystem, and decreasing biodiversity, which is becoming a huge threat to the survival of Earth's organisms.

Huge changes in the climate have been occurring a long time ago, and they seem to have a cycle. The Earth ended a lesser ice age at the end of the 19^th century, and the temperature has slowly risen. However, the rise has not been steady and continuous; some of the rises have been quite short. The average ground temperature rose relatively quickly at the beginning of the 20^th century, reaching a high in 1940. The temperature rose 0.6℃ during the 35 year period ending in 1940, then dropped in the 50s, slightly rose in the 60s, but basically stayed low until the 1980s, where it then swiftly rose again. After 1980, there were a few small drops, but the general rise was maintained till it's peak in 1995. It should be noted that a rise in the general global temperature doesn't necessarily mean a rise in every area. Some places may see a more obvious rise in temperature, some may not see much change, and some places may even witness a drop. Regional changes in climate obviously exhibit a much more complex pattern then global changes.

A summary of the changes in global climate trends spanning the 20^th century.

A.A rise of 0.6°C in the global average ground temperature.

B.Since 1950, the frequency of extreme low temperatures has dropped, while the frequency of extreme high temperatures has slightly increased.

C.The sea level has rose 0.1~0.2 m.

D.The frequency of severe droughts and floods has increased.

E.The frequency of severe rain showers has increased 2~4% in the middle to high latitude areas of the northern hemisphere.

F. In continuation with E, the rain fall per 10 years has increased 0.5~1%, while tropical areas have seen an increase of about 0.2~0.3%. However, most of the northern hemisphere's subtropical areas have witnessed a 0.3% drop in the accumulated rainfall per 10 years.

G.The middle to high latitude areas have seen a 2% increase in cloud amounts.

H.From ground observation data, the period of ice coverage for lakes and rivers in the middle to high latitude areas of the northern hemisphere have been decreased by 2 weeks.

I.Satellite data shows that there has been a 10% drop in the global snow coverage area since the end of the 1960s.

Phenomenon caused by global climate changes

A.The WHO pointed out last December that the average global temperature had reached the 5^th highest since records started being kept 140 years ago. Currently, the 5 highest average temperature years have been 1998, 1997, 1995, and 1990.

B.The US recorded the highest winter average temperature in the last 103 years between 1990~2000.

C.Last year England suffered from one of the most serious floods in the past 50 years. Last April, England and Wales recorded the highest amount of rainfall in the past 235 years. This summer though, England suffered from a drought problem.

D. The Mekong River, which passes through China and the Indian Peninsula suffered from an extremely devastating flood last summer. According to the Red Cross, 500,000 people were affected by the floods and left homeless in Thailand and 3 provinces on the borders of Vietnam and Cambodia.

E.2.4 million livestock perished in a 1999 drought in Mongolia.

F.This spring, the East African area has been hit by one of the most severe droughts in history, and millions are in need of help.

G.The spring rainfall in the Korean Peninsula has been the lowest since 1904, being most severe in the middle of the peninsula while the rainfall in the southern areas of North Korea in March is only 10% of the usual.

H.As the Washington Post reports on July 1^st, Mainland China is suffering from one of the worst droughts in 20 years, ranging over 17 provinces, with 23 million people in need of drinking water, and 73 million acres of farmland in waste.

I.Poland was struck by heavy showers around the end of July, thousands were forced to evacuate, and at least 28 are dead. There were over 5 thousand hectares of farmland flooded, and the property losses were over 10 million US dollars.

J.On August 7^th, rare rain showers occurred in Shanghai, which had rarely been seen in the past decade, and 30,000 homes were flooded.

Figure from Phenomenon caused by global climate changes- Long term development group

　　　　　　　http://www.npf.org.tw/PUBLICATION/SD/090/SD-R-090-030.htm　August 10,2001