“Further global warming of 1 °C defines a critical threshold. Beyond that we will likely see changes that make Earth a different planet than the one we know.” Read the article.
According to Jim Hansen, director of NASA’s Goddard Institute for Space Studies in New York, the idea that we have a long time to figure out solutions to the global warming problem is completely wrong. In fact, we have a narrow window of time to reverse course, because we are on the threshold of what scientists fear most–runaway global warming, where the warming drives changes that drive more warming. Hansen’s team concluced that even one more decade of global warming pollution that’s business as usual will probably make it too late to prevent northern ecosystems from changing in dramatic ways that trigger runaway warming (Proceedings of the National Academy of Sciences, vol 103, p 14288).

Hansen and colleagues have analyzed global temperature records and found that surface temperatures have been increasing by an average of 0.2 °C every decade for the past 30 years. Warming is greatest in the high latitudes of the northern hemisphere, particularly in the sub-Arctic boreal forests of Siberia and North America. Here, the melting of ice and snow is exposing darker surfaces that absorb more sunlight and increase warming, creating a positive feedback.

Earth is already as warm as at any time in the last 10,000 years and is within 1 °C of being its hottest for a million years, says Hansen’s team.

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