Moreover, to stabilize atmospheric concentrations at levels that will avoid dangerous climate change the entire world will need to peak its emissions in the next few years followed by emissions reductions at hard to imagine rates over the next 40 years. The following chart shows the emissions reduction pathways that are needed in this century to give the world any hope of limiting warming to 2 degrees Centigrade. The later the peaking of global total emissions, the steeper the reduction pathways that are needed. (The different colored lines represent different emissions scenarios in the years ahead)(Anderson, K. 2011)
And so, the US projected emissions reductions fall far short of the 25 to 40 % emissions reductions below 1990 levels by 2020 that are likely necessary to put the world on a pathway that gives any hope of limiting warming to the dangerous 2 degree C warming limit that has been agreed to. Furthermore there is some inconclusive evidence that to prevent dangerous climate change the warming limit should be 1.5 degrees C, a matter that will be investigated under the UNFCCC in the next few years.
If a 1.5 degrees C warming limit should be the goal of the international community rather than 2 degree C, the international community will need to dramatically increase it emissions reductions ambitions to hard to imagine levelst. In fact, all of the commitments made by all nations under the UNFCCC fall far short of the emissions levels necessary to prevent the 2 degree C warming limit . The following chart describes the gap between the emissions reductions commitments that nations have been made under the UNFCCC.
According to a recent report by the United Nations Environment Program, to have any chance of limiting warming to 2 degree C total levels in 2020 must be no greater than 44 GtCO2e (with a range of: 41-47 GtCO2e). Afterwards, global emissions must steeply decline (a median of 2.5% per year, with a range of 2.0% to 3.0% per year) to 2050.
Because current global greenhouse gas emissions, based on 2010 data, are estimated at 50.1 GtCO2e the world is emitting emissions 14% higher than the median estimate (44 GtCO2e) of the emission level in 2020 needed to have any hope of limiting warming to the 2 degree C target and global emissions are currently increasing at 2 to 3% per year, the world is running out time to prevent dangerous climate change (UNEP, 2011).