In the northern hemisphere, the southern part of the Arctic region (home to 4,000,000 people) has experienced a temperature rise of 1 °C to 3 °C (1.8 °F to 5.4 °F) over the last 50 years. Canada, Alaska and Russia are experiencing initial melting of permafrost. This may disrupt ecosystems and by increasing bacterial activity in the soil lead to these areas becoming carbon sources instead of carbon sinks. A study (published in Science) of changes to eastern Siberia's permafrost suggests that it is gradually disappearing in the southern regions, leading to the loss of nearly 11% of Siberia's nearly 11,000 lakes since 1971. At the same time, western Siberia is at the initial stage where melting permafrost is creating new lakes, which will eventually start disappearing as in the east. Furthermore, permafrost melting will eventually cause methane release from melting permafrost peat bogs.
Prior to March 2004, no tropical cyclone had been observed in the South Atlantic Ocean. The first Atlantic cyclone to form south of the equator hit Brazil on March 28, 2004 with 40 m/s (144 km/h) winds, although some Brazilian meteorologists deny that it was a hurricane. Monitoring systems may have to be extended 1,600 km (1,000 miles) further south. There is no agreement as to whether this hurricane is linked to climate change, but one climate model exhibits increased tropical cyclone genesis in the South Atlantic under global warming by the end of the 21st century.
Tuesday, December 1, 2009
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment