2022 looks set to be the 4th/5th warmest year averaging 0.86C above the 1961-1991 baseline after 10 months. The underlying trend is better represented by the decadal integration which implies an overall warming of about 1.2C since the “pre-industrial” period. (Note however that coverage uncertainty increases pre 1960, especially ocean temperatures).
Annual temperatures calculated by spherical triangulation. The Decadal temperatures are calculated independently using a 10 year integration over an icosahedral grid.
La Ninja remains a strong influence.
October 2022 regional temperatures are visualised below.
Regional temperature anomalies. La Nina remains strong.
The decadal trend in global temperatures shows a clear almost linear increase since the 1970s. We can compare this increase to that of CO2 in the atmosphere.
Comparison of decadal temperature increase with Moana-Loa CO2 measurements.
One sees a nearly proportional agreement between temperature and CO2 after ~1970. However CO2 levels have recently been rising faster than linear as highlighted by the green arrow. So the question is can we isolate what the climate response is to CO2 and measure the climate sensitivity?
Each decadal temperature measurement has an associated average CO2 value for that decade. Is the global temperature a simple function of CO2 and if so how does that compare to theory ? One problem we have is that the early data from 1850 to 1960 shows a non linear trend. There are two possible reasons for this. Either the effect is real and there was a natural variability before 1960 or instead the early data coverage was not reliable enough to infer trends.
Decadal temperatures from 1850 – 2020
However for arguments sake we will ignore this and assume that the trends are correct. So next we plot the temperature rise versus CO2 levels and compare this to the logarithmic radiative formula I derived earlier here. For each decade I calculate the corresponding average CO2 level . In this way I can then plot temperature versus concurrent CO2 level and compare this to the logarithmic temperature dependence.
Unfortunately there is still a normalisation problem because global temperatures are always calculated as anomalies relative to some 30 year baseline period, (1961 – 1990) in my case. CO2 levels in 1970 were 330ppm so I simply normalise the result to this value. Then we can derive a “rough and ready” climate sensitivity to increasing CO2 levels.
With these assumptions a doubling of CO2 would lead to a 1.7C net increase in global temperatures relative to what appears to have been a cooler period in the 19th century.
Long term temperature trends are best visualised on decadal timescales. This is because it smooths out short term local effects caused for example by ENSO and other ocean oscillations. My method to achieve this in a consistent way uses an icosahedral grid where each equal area cell is averaged over 10 years (see here). I have now updated my previous results to cover also the 2011-2020 decade. These results are shown below. If you click on each header such as 2011-2020 West-Hemisphere then you access the 3D icosahedral gridded temperature data directly. Simply click and spin the globe (thanks to Nick Stokes!)
The colour scale shows temperature differences relative to a baseline of 1961-1990
The warming trend since 1970 appears to be linear as shown below.
Ten year average temperatures based spherical triangulation of GHCN4/HadSST4
Overall the world has warmed by about 0.8C starting around 1965. However, CO2 levels have if anything been rising faster than the temperature response.
Moana Loa CO2 measurements.
The temperature response appears to be linear to an exponential increase in CO2 levels. Therefore there is no evidence of any positive climate feedback to CO2. Instead it is far more likely to be a negative feedback.
We need to eventually stop burning fossil fuels and find realistic alternatives, but there is no imminent “climate emergency” or “climate breakdown”.
. Thanks to Nick Stokes for the WebGL visualisation