As this is my last post before Christmas I thought I would look forward to some good cheer and also perhaps some seasonal gifts. Here’s my request to Father Christmas at the North Pole (or according to your preferred tradition Papa Noel, St Nicolas, Santa Claus, or another bringer of good cheer at this time of year).
“Dear Father Christmas,
can we please have for Christmas something that makes global carbon dioxide emissions rise no more than 0.5 % p.a. until they reach that peak, leads them to peak in 2025, and then fall at 3.5% p.a. forever, so that global temperatures this century increases by no more than 2.0 degrees centigrade due to extra carbon dioxide in the atmosphere.
You can fill in your own numbers for your own particular wish in this spreadsheet
Adam Whitmore’s summary of the Allen and Stocker model
Sometimes it seems like it will need a miracle from Father Christmas to get to the sorts of numbers you have probably entered, certainly if they are like mine. But if the world can at least make good progress towards these numbers next year, it will make the best Christmas present the planet could have.
Here’s hoping it works out that way, and in the meantime enjoy the holiday season.
Adam Whitmore – 18th December 2014
If you want to know more about the basis of this calculation see my earlier post here. The parameters define cumulative CO2 emissions given current emissions (area under the curve), and this converts to linearly to temperature. I’ve assumed a transient climate response to emissions (TCRE) of 2 degrees, a variable which is subject to considerable uncertainty. The calculation is for CO2 warming only, and there may be another perhaps 0.4 degrees due to other greenhouse gasses, so you might want to be more ambitious about what you wish from CO2 than I have been here, even though the numbers already look rather ambitious.