Carbon budget? What carbon budget?

From Climate Code Red.

There's a lot of delusional talk about how much "carbon budget" (or new emissions) are allowable that would still keep global heating to the Paris target of 1.5 degrees Celsius (°C). The reality is that over the last year, global average warming was already close to 1.5°C, based on a true, pre-industrial baseline.

And the warming already in the system may well be enough to take the planet past 2°C, without any more emissions. The propositions pushed by governments, big business and many large climate movement NGOs that we have a "carbon budget" available for the Paris targets runs contrary to the evidence and suggests a world of politically convenient make-believe. 

Global warming July-to-June, illustrated here with a 1981-2010 baseline.  Image by CarbonBrief.

Here's why:

• According to CopernicusECMWF, globally, the twelve-month period from July 2019 to June 2020 was 0.65°C warmer than the 1981-2010 average (see chart above).

• Then 0.63°C should be added to these values to relate recent global temperatures to the pre-industrial level defined as a late 19th century baseline.

• So warming for the period July 2019-June 2020 is 1.28°C, compared to the late 19th  century, for which instrumental temperature records are available from 1850.  This ties with the warmest year on record.

• But there was also warming from the start of the industrial revolution and the use of coal from the mid-eighteenth century, up to the end of the nineteenth century. That figure ranges up to 0.19°C, according to Importance of the pre-industrial baseline for likelihood of exceeding Paris goals. 

• And new research published last year found that gaps with missing data in the observational temperature record are responsible for an underestimation of the global warming between 1881–1910 and 1986–2015 by 0.1°C.

• Adding up all those components takes the warming over the last year, from a true pre-industrial base, very close to the lower end of the 1.5-2°C Paris goal, whilst recognising there is some uncertainty about warming in the pre-1850 period. 

The article then goes on to argue that there are some signs that the recent decadal temperature rise has increased from 0.2 degrees C to 0.3 degrees C, and although we don't have enough data to be sure—we'd need 20 to 30 years to confirm a new trend—it's very plausible that the steady and accelerating rise the atmospheric CO₂ and methane is leading to a more rapid rise in global temperatures.

I do the calculation more simply.  If global temperatures continue to rise by 0.2 degrees per decade, and we are already up by 1.3 degrees since 1850, and assuming it takes 3 decades (2050) to get to zero emissions, global temperatures will rise by another 0.6 degrees between now and then, taking the increase over 1850 to 1.9.  Which assume that the rise per decade isn't increasing.  There's no way we're going to limit the rise to 1.5 degrees C.

The whole concept of a carbon budget is misleading.  In the simplest possible terms, we need to cut our output of CO₂ and methane as much as possible as rapidly as possible, never mind what "budget" we are supposed to have left.  And every year that we don't cut emissions takes us closer to disaster. 

There are some hopeful signs: the continued decline in the costs of renewables and storage; the cost declines in EVs.  On the other hand,  subsidies to fossil fuels continue, and China, the world's largest polluter, continues to build new coal power stations, and fund them in developing countries.  We need to cut emissions by 3.3% of the 2020 level each year to halve emissions by 2035.  That's perfectly doable if we transition electricity generation and land transport, which cause half of all emissions.  Renewables are now cheaper than fossil fuels in most markets, and of course continue to get cheaper still all the time.  And we have already seen the emergence of an EV which costs $10,000.