The anthropogenic hypothesis holds the rising concentration of greenhouse gases is due to human activities alone with no contribution from natural sources. Natural sources can be the result of temperature change from non-greenhouse gas drivers and from natural sources (e.g., ocean, landmass).
Atmospheric GHG has been growing steadily with no material change in slope for more than 60 years. Over that period, climate temperature has varied – cooling in the late 1970s, rising in the 1990s, and then slowly as the solar Modern Minimum approached its end.
Satellite radiometers are the most consistent and most reliable temperature record and data only goes back some 40 years. Here is the satellite record as reported by the University of Alabama.
Simulations generated by IPCC’s CMIP5 is the basis for the UN agency’s claims of a climate crisis. CMIP5 tends to run hotter than actual data.
In the top image of this post, Dr. Roy Spencer (University of Alabama, Hunstville) compares 108 CMIP5 simulations against surface temperatures in Canada recorded over 30 years over latitudes encompassing 51N to 70N.
For observations, Spencer used the same lat/lon bounds and the CRUTem5 dataset, which is heavily relied upon by the UN IPCC and world governments. All data were downloaded from the KNMI Climate Explorer.
We see that Canada has been warming at only 50% the rate of the average of the CMIP5 models; the linear trends are +0.23 C/decade and +0.49 C/decade, respectively. Note that in 7 of the last 8 years, the observations have been below the average of the models.
This finding is consistent with other backtests reported in the peer-reviewed literature.
Simply put, IPCC forecast models “run hot”.
I suspect one of the reasons is that IPCC models assume a much higher ECS than consistent with the current literature. This is not a recent problem:
In the 25 years of IPCC’s First to Fifth Assessment Reports [1–5], the atmosphere has warmed at half the rate predicted in FAR. (Moncton, 2015)
Several researchers observe natural variation (i.e., not caused by GHG) to explain the CMIP model problem, resulting in the poor model performance evident in this 2017 analysis and presentation to Congress:
Christy explains the problem as due to unduly sensitive estimates of climate sensitivity to GHG.
Canada is warming at only 1/2 the rate of climate model simulations « Roy Spencer, PhD. (n.d.). Retrieved January 22, 2021, from Drroyspencer.com website: http://www.drroyspencer.com/2021/01/canada-is-warming-at-only-1-2-the-rate-of-climate-model-simulations/
Christy (2017) https://science.house.gov/imo/media/doc/Christy%20Testimony_1.pdf?1
Monckton, C., Soon, W. W.-H., Legates, D. R., & Briggs, W. M. (2015). Why models run hot: results from an irreducibly simple climate model. Science Bulletin, 60(1), 122–135.