Spending the Carbon Budget

Everyone is familiar with the idea of a “budget”.  It’s the amount you can afford to spend or allocate on certain things.  Once it’s all spent, that’s about it unless you overspend and are prepared to face the consequences like debt or bankruptcy.

The Paris Climate Accord seeks to limit global average temperature rise to 2°C, or even better 1.5°C (it’s already risen about 1°C).  One way of looking at it is to estimate (from the physics of climate) how much more carbon dioxide we can afford to emit into the atmosphere.  That’s our “carbon budget”, and if we overspend this budget the laws of physics will make it impossible to keep the temperature rise below our desired target.

One research institute in Germany has created a nice carbon budget clock.  It shows, based on the remaining budget and the rate of “spending” (i.e. emissions), how much time we have left until the temperature target becomes an impossibility. Here is a recent screen-shot of the countdown clock (click on the link for a live version).

Carbon budget remaining for 1.5C target, as of May 14, 2019.

Unfortunately, there is less than 9 years until we blow the 1.5°C budget.  This doesn’t mean the global average temperature rise will suddenly jump to 1.5°C, but it means that it will eventually rise that high and there is essentially nothing that will stop it.  Like with gravity, the laws of climate physics can’t be broken.   However, if we can slow down the spending (emissions), we can stretch our budget out over a longer time.  So far that hasn’t been happening, as seen below in the emissions graph from the past 20 years.

Engineers and others have the knowledge and ideas to reduce the carbon emissions rate.  We just need the collective societal will and government leadership to do so.  Hopefully well before the carbon budget is already spent, because it will take time.  Here is a rough estimate of where the temperature is heading over the next couple of decades based on current rates.

Very rough estimate of future global average temperature rise, from Berkeley Earth project.

It looks like we will reach 1.5°C around 2040, and 2°C around 2060, unless emission rates drop significantly and soon. That won’t stop the rise, only delay it somewhat. Achieving net-zero emissions is the only way to stop the rise. Unfortunately with the current leaders (and prospective leaders) in Canada and around the world the hope for emissions reductions seems dim. So, prepare for the continuing consequences.


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