Rise in world's temperatures accelerates

 Open Mind (Tamino) produced a previous piece about the acceleration in the rise in global temperatures, which I reported on here.  He has returned to the analysis, and confirms his position in his latest post. 

I now have global temperature data through October of this year from NASA, NOAA, and ERA5, as well as data through September from HadCRU and Berkeley. I’ve translated them to “since pre-industrial” values using one of the methods in the IPCC special report on 1.5°C. Then I computed yearly averages (this year is incomplete so values for 2024 are year-so-far averages)

There are two clear episodes in this plot: before and after 1975. Before, GMST was fluctuating but not trending either way; since, it has been trending consistenly up and fluctuating. As for its rate of increase, for four and a half decades (from 1975 until 2020) temperature seemed to rise at a pace (about 0.02°C per year) that was unchanging, and statistics couldn’t deny it.

But the last two years (2023 and 2024) have been “off the charts,” so to speak. For the data from ERA5, the value for 2024 year-so-far is already above 1.5°C, which is exactly what the Paris agreement seeks to avoid.

I investigated the rate of warming, and how it may have changed over time, in two ways. First, I fit a modified lowess smooth which I’ve programmed to estimate the rate as well as the value. Second, I computed a piecewise linear fit (PLF) with knots at 1975 and 2010. Both models (lowess and PLF) were fit to the monthly-average data, but in the graphs that follow I’ll plot yearly averages so the graphs will be less cluttered. Here’s how the PLF model fits the data from NASA:

PLF = piecewise linear fit 

 

[....]

For the 45-year period from 1975 through 2009, the average warming rate according to NASA data is just about 0.018°C/yr. For the 15-year period since 2010, it has been a lot faster at 0.031°C/yr. Statistically, the difference is significant at over 99% confidence.

I have also adjusted all the data sets, to compensate for the influence of el Niño, volcanic eruptions, and solar variations, with a method not unlike that of Foster & Rahmstorf (2011). Here are the adjusted temperatures, together with their PLF fit, for the data from NASA:

This chart shows the temperature anomaly adjusted for El Niño/La Niña and for vulcanism. 
PLF = piecewise least fit.

The rate from 1975 to 2010 now seems to be only 0.017°C/yr, and after 2010, the best estimate is 0.033°C/yr. These aren’t much different from the estimates using the raw data, although the uncertainties are now smaller so the confidence intervals are narrower.

Falling emissions (which of course we don't have--emissions continue to rise) do NOT mean that temperatures will start falling.  The RISE in the temperature anomaly is proportional to the LEVEL of emissions.  In other words, for temperatures to stop rising, we need to reduce emissions to zero.  If we halve emissions, the increase in temperature anomaly will halve, but that only reduces it to what it was before this recent acceleration, 0.17 degrees per decade.  

There are positive signs that emissions will peak soon.  Wind and solar continue to expand exponentially.  The costs of battery storage are plunging, and the recent first commercial solid-state battery point to continues and sustained cost declines and efficiency improvements.  Yet, even if we completely switch ALL electricity generation and ALL land transport to carbon-free methods, that will still only halve emissions.  If we were to start cutting emissions by 5% a year, compound, it would take us 40 years to reduce emissions to 10% of current levels.  Assuming we did this (but we are not) temperatures would rise for the next decade by 0.33 degrees, for the decade after by 0.17, by the decade after that by 0.l2 degrees and for the final decade by 0.06.  Roughly.  In other words, temperatures would rise by another 0.33+0.17+0.12+0.06, or ~0.7 degrees, making the rise since 1850-1900, the traditional "pre-industrial" starting point 2.2 degrees.

We face catastrophe, and still we dither and phaff.  The Right is dead against doing anything at all to slash emissions, and the Left argues with itself about what to do.  Meanwhile, we are lied to by corporations and governments, and protesters go to jail while oil execs are fêted.