(Reuters) – A recent slowdown in the rise of the Earth’s surface temperatures has led some commentators to question whether scientists have exaggerated the global warming problem.
…Scientists have provided a wide range of views on how the planet could respond to a doubling of carbon dioxide levels, a measure known as climate sensitivity.
One area of uncertainty is whether the net effect of more clouds will lead to warming or cooling.
The record for observed surface temperatures (there are few observations in the deep oceans) in the past decade have found no evidence for an extreme response to greenhouse gases.
…There are plenty of potential causes for a blip in the warming trend besides a revised assessment of the impact of greenhouse gases.
Candidates include manmade aerosols from a huge increase in coal burn in the past 10 years in China (which forms hazy clouds that can reflect back sunlight and cool the Earth); changes in the El Nino Pacific Ocean weather pattern (which warms the Earth and whose last big maximum was 1998); an observed fall in stratospheric water vapour (a strong greenhouse gas); and the role of the deep oceans in masking surface warming by sequestering heat.
Without scientific certainty, governments will probably maintain their default positions regarding international action