The Copenhagen Accord reaffirms the importance of limiting global warming to 2 °C (3.6 °F), but current national commitments would lead to approximately 3.9 °C (7.0 °F) warming by 2100.
To close that gap global emissions must peak within the next decade and fall approximately 50% below 1990 levels by 2050 (a cut of approximately 60% below current emissions).
The sooner the nations of the world begin to close this gap the cheaper and easier it will be.
The Climate Interactive research team from Sustainability Institute, the MIT Sloan School of Management, and Ventana Systems have analyzed the greenhouse gas emissions reductions targets stated in the final Copenhagen Accord and compared these with the emissions reduction commitments made by individual nations. The analysis, based on the C-ROADS climate policy simulation, assumes that all national commitments offered prior to and during the Copenhagen meeting remain in force, are verifiable and will be fully implemented.
The Accord adopted in Copenhagen (accessed 19 December 2009) calls for “deep cuts in global emissions…so as to hold the increase in global temperature below 2 degrees Celsius” compared to preindustrial levels. Simulations of the C-ROADS model show that doing so requires global greenhouse gas emissions to peak by 2020 and then fall 50% below 1990 levels by 2050 (a cut of approximately 60% below current emissions).
However, simulations of the C-ROADS model show a large gap between the targets in the final Copenhagen agreement and the commitments offered by individual nations. Using the C-ROADS model, the researchers estimate that current confirmed proposals (that is, submissions to the UNFCCC or official government positions) would raise expected global mean temperature by 3.9 °C (7.0 °F) by 2100. Including conditional proposals, legislation under debate and unofficial government statements would lower expected warming to an increase of approximately 2.9°C (5.2°F) over preindustrial levels. Full details and assumptions are here. …