climate change
The global climate has seen significant changes over the past century, with global temperatures having risen consistently over this period. This rise has been most significant in the past few decades and with no evidence to suggest that this trend will divert from this course and cease, the potential of forthcoming global environmental disaster is real and extremely distressing. (Birkeland, 2004)
Eleven of the hottest years since 1850 have occurred between 1995 and 2006 and the 1990’s was recorded as the hottest decade in history. In 2007, the United Nations Intergovernmental Panel on Climate Change (IPCC) reported that the earth was approximately 0.75C warmer than it was in 1850 (Pitts, 2004). This may appear negligible, however small difference in average temperature can have a significant impact on climate change. This change can be put into perspective when viewed in terms of historical comparisons. For example, during the last global ice age the earth was only about 5C colder than it is now (Cairns, 2004).
The substantial temperature increase over the last 30 years have seen a 10% decrease in the Northern Hemisphere’s amount of ice and snow coverage. Furthermore, glaciers and ice caps have depleted significantly in polar and non-polar regions alike (Pitts,2004). In 2005, the Zurich- based World Glacier monitoring service stated that European glaciers had lost half of their volume since 1850. The melting of these large tracts of ice has resulted in average sea levels rising up to 0.2 metres. This ostensibly modest rise, while seemingly insignificant, can and has had dramatic and devastating consequences for low lying areas worldwide. (Pitts, 2004)
Rainfall and humidity levels have shifted on a global scale over the past 100 years, with an increase over northern continental latitudes and a decrease in sub-tropical zones. Warmer temperatures are also responsible for a 2.2% increase in the earth’s humidity over the past 30 years (Carpenter,2001). Cloud cover and instances of heavy rainfall have intensified in the Northern Hemisphere as a result. The phenomenon known as El Nino, which has been the cause of several disastrous climactic events in the Pacific region has increased in severity and consistency over the past few decades. (Yeang, 1999)
The earth’s temperature has experienced natural variations over its lifetime, with periods of relatively cold temperatures and periods that are relatively warm. These past variations, however, occurred gradually over time. But in the 20th and 21st century, especially in the last 30 years, temperatures have risen more quickly than during any century in the past 1000 years (Pitts, 2004). The change in climate to some extent be explained by natural variations and natural climactic events, but the IPCC has concluded that human activities, in particular the emissions of certain gases, has altered the earth’s atmosphere and the climate. This influence will continue to prevail and intensify change temperature levels unless there is a shift in human activity which causes the emissions of greenhouse gases. (Williamson et al, 2003)