The World Bank yesterday released a report prepared by the Potsdam Institute spelling out what the world is likely to experience if it warmed by 4 degrees -- that's looking increasingly likely by the end of the century without some serious policy changes by governments globally.
The report essentially attempts to summarise much of the research literature that has built up since the 2007 fourth IPCC Assessment Report and puts it in the context of the path we’re on unless we start taking this problem seriously. It doesn't make for pleasant reading. World Bank President Dr Jim Yong Kim says "it is my hope that this report shocks us into action", as he believes "a 4 degree world can, and must, be avoided".
For the World Bank, with a primary purpose to help impoverished nations out of poverty, "the lack of action on climate change not only risks putting prosperity out of reach of millions of people in the developing world, it threatens to roll back decades of sustainable development".
The chart below provides an impression of the alternative emission paths and their likely implications for temperature rise. According to the report, we are on a path illustrated by the red line. However, if governments follow through on the pledges they've made at the UN's Copenhagen and Cancun summits then it would put us on the purple line, giving a mean temperature rise estimate of 3 degrees.
But even this path still carries a 20% chance of temperature exceeding 4 degrees. If governments don't make good on their pledges then the red line would imply a 40% chance of warming above 4 degrees.
Median estimates of temperature rise from probabilistic projections for several scenarios