Despite 17 years of negotiations since the 1992 Rio Earth Summit, global greenhouse gas emissions have continued to rise. Since 2000 the rates of annual emissions growth have increased at rates at the upper end of the IPCC scenarios, presenting the global community with a stark challenge: either instigate an immediate and radical reversal in existing emission trends or accept global temperature rises well beyond 4°.

The immediacy and scale of the reductions necessary to avoid anything below 4°C, and indeed the human and ecosystem implications of living with 4°C, are beyond anything we have been prepared to countenance. Understanding the implications of 4°C and higher temperatures is essential if global society is to make informed choices about the balance between "extreme" rates of mitigation and "extreme" impacts and adaptation costs.

The aim of this conference is therefore to: (i) assess the consequences of a change in global temperature above 4°C for a range of systems and sectors, and (ii) explore the options that are open for avoiding climate changes of this magnitude. The results of the conference will form an important background to the COP 15 United Nations Climate Change Conference, in Copenhagen, December 2009, and the inevitable negotiations that will follow COP 15.