Humans are the main cause of global warming


Climate Change


Credit: NASA

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BRISBANE: An annual review of climate science by the World Resources Institute (WRI) has provided further evidence that humans are the main cause of global temperature rises in the last century, and highlights the urgent need for substantial greenhouse gas mitigation.

The WRI Climate Science Issue Brief is an annual report for non-scientists that documents climate change impacts, describes their potential ramifications and identifies technological advances from work published in prestigious peer-reviewed scientific journals such as Nature, Science and Proceedings of the National Academy of Sciences.

Covering research into the physical climate, the hydrological cycle, ecosystems and ecosystem services, the Brief makes grim reading, although 2008 also saw some promising innovations in climate change mitigation technologies.

Corals, alpine species, glaciers, food security, and human populations that rely on glacial run-off or ocean fisheries are all in the firing line, according to the report.

Some of the papers covered by the report reconstruct past climate events, such as two papers using Antarctic ice cores to show that greenhouse gas levels today are higher than any time in the past 800,000 years.

Another paper examined a metre-long stalagmite, revealing that fluctuations the Asian monsoon correlated with the rise and fall of several Chinese dynasties, with weak monsoons coinciding with periods of major social unrest.

Other papers highlighted by the report deal with likely future effects of climate change, such as a one reporting a feedback loop between sea ice loss and land warming that could increase land temperatures up to 1,500km inland in the Arctic and lead to wide-scale permafrost degradation.

One paper suggests that, even with stringent mitigation regulations, temperatures may rise more than the current target of 2 C over pre-industrial levels, making climate adaptation efforts essential, and another suggested that daily maximum temperatures could rise to 50 C in Australia if carbon dioxide concentrations double by 2100.

Researchers reported in Science that dead zones in tropical oceans - areas that lack oxygen and cannot support life - are likely to increase by 50 per cent in the next century, affecting the millions of people who rely on fisheries for food.

Not all the effects of climate change lie in the future, however, as shown by several papers highlighted in the Brief.

The World Glacier Monitoring Service showed that 30 glaciers around the world had doubled their rates of melting between the 2004-2006 and 2005-2006 seasons, and a Nature meta-analysis of the changes in 28,800 plant and animal species between 1970 and 2004 show that global warming is already having a significant impact on ecosystems world-wide.

In just one example, scientists found that anthropogenic warming promoted beetle infestations in the forests of British Colombia so much that the forests, once a carbon sink, are now becoming a large carbon source.

However, some promising technologies to mitigate climate change are also being developed, including solar cells with vastly improved efficiency, better batteries for storing renewable energy, cheaper, non-toxic methods of generating hydrogen from solar power or biofuel, and a method for capturing carbon dioxide straight from the air.