Pachauri goes on to describe the steps humanity will need to take in order to adapt to the changing conditions: reforming agriculture, erecting better flooding protection measures, reducing water scarcity and helping developing nations cope. Despite the grim scenario he lays out, Pachauri is hopeful that humans will step up to this immense challenge; he dismisses the doom-mongers by asserting that, "if we start today, we can really make a difference in the next two to three decades."
Here's Rajendra K. Pachauri's panic-inducing assertion: We have a window of seven years to stabilize CO2 at today's levels if we are to limit our global mean temperature increase to around 2.40C. A world this hot would be a very unpleasant place to be. Pachauri lays out unequivocal" evidence of climate change, and describes how extreme precipitation events, heat waves and other natural catastrophes will become more frequent, endangering vast swaths of humanity. We stand to lose 20-30% of species if warming exceeds 1.5 to 2.5 0C. Pachauri also notes this "scary prospect": the rapid loss of ice sheets on polar land, leading to sea level rises of several meters, and the flight of large populations in response.
Stabilizing atmospheric carbon dioxide levels around 500 ppm (for a more ambitious take, head over to Joe Romm's blog or Bill McKibben's 350.org site) by 2030 would incur costs amounting to less than 3% of global GDP, or a paltry .12% annually, Pachauri says. Key to achieving this emissions goal will renewed investment in public transport, renewable energy technologies and more efficient vehicles, he elaborates.