A September, 2009, conference at Oxford examined the climate impacts of a global mean four degree (C) temperature rise, and compares those impacts with impacts of a two degree (C) world.

The Royal Society, the oldest scientific academy in existence and home to some of the world’s most preeminent scientists, has just published an issue on the four degrees–warmer theme.

While the international community agitates for a 2 degrees Celsius cap on climate warming, many scientists are predicting that we will inherit a world warmer than 2 degrees Celsius. Under a 450 ppm scenario, for example, there is a 50 percent chance of meeting the 2 degree (C) temperature threshold. Every year since Rio, global climate emissions have increased. Thus from a legal standpoint, developed countries have an obligation to prepare for the worst case scenarios of a three, four, five, even six degree (C) warmer world (applying the range of warming projections reported by the IPCC), despite our best intentions for mitigation.

The Royal Society articles consider a range of climate impacts and human adaptation challenges, such as sea-level rise, population migration, and water availability. You can download the articles here.