You may have heard that global climate change is happening faster than predicted. A recent feature in the New Scientist (17 November, 2012), ‘Global warning’ by Michael Le Page, describes the current situation, as does this blog on the Scientific American website:
Polar melting is accelerating, as is sea level rise.
Climate models are having to be updated as more data is gathered worldwide and as methodology is refined. In 2007 the IPCC Intergovernmental Panel on Climate Change (IPCC) predicted a global temperature rise of 4 deg C by 2100 as a worst case scenario. More powerful models developed since then by the MIT in the USA and the Met Office in the UK suggest that the 4 deg level will be reached by 2070 or before. By 2100 it could be as high as 7 deg C (10% chance).
Overall, the acceleration arises from both natural and man-made causes. The main points:
More importantly, natural trends (e.g. changes in the Earth’s orbit) seem to be adding to the rate of climate change calculated by even the updated models and despite green measures the carbon emissions per capita are rising world-wide as the developing world seeks to emulate the extravagant life style of westerners.
- Only very small changes 5,500 years ago turned the savannahs and wetlands of N.Africa into the Sahara desert over a relatively short period - centuries, perhaps decades.
- 5 to 3 million years ago the world was 2 to 4 deg C warmer than today. According to K Emanuel et al (MIT, USA) the rising number of hurricanes altered the distribution of heat in the oceans and tipped the global climate into a different state, with warmer tropics and hurricanes over a much larger area than today.
- A mass extinction 250 million years ago is thought to have been caused by temperatures being too high for most animals.
see also http://www.scientificamerican.com/article.cfm?id=how-the-ipcc-underestimated-climate-change
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