Carbon Budget

Dec 2015 = 401.85 ppm CO2

Dec 2016 = 404.48 ppm CO2

This represents an increase of 2.63ppm year over year. Converting ppm CO2 into GtCO2 multiply by 7.81 .

This tells us there is 20.54 GtCO2 more CO2 in the air than the year before. The earth absorbs half so 41 GtCO2 was emitted by man and natural forces.

In terms of PgC or GtC 41/3.67 = 11.17 GtC was emitted in the year and half was absorbed by the earth.

The remaining carbon budget is 485PgC @ 2011, in 2017 it is 485-55 = 430PgC @ 2017

If we are to stay within their 2C limit we have 430/11= 39 years at Business as usual levels.

However there is one major problem:

Read the fine print of the bottom infographic. If we factor non-CO2 gases the available budget drops to 275PgC @ 2011. Adjust that for now 275-55=220PgC @ 2017 or 20 years remaining. In ppm terms this would be 60ppm CO2 more or 22 years at current growth rate. 464ppm is the 2C budget target assuming all non-CO2 gases remain constant.

There is one additional problem. The non-CO2 GHG assumption is based on RCP2.5, which is the most conservative estimated scenario. So it is very likely that we have less than 20 years to hit the 2C carbon budget ie 2026-2036.

Still more problems:

• Piece it all together. They are saying we have 20 years to reduce CO2 emissions to zero, otherwise we overshoot 2C.
• Albedo loss has not been factored, According to Wadhams a .6C rise can be attributed to arctic albedo loss alone.
• Global Dimming is only used as parameter to offset forcings. They have not included the implication SO2 reduction in emissions, you will get an immediate rise temps up to about 1C or more.