A Simple Question for Climate Alarmists

What physical evidence supports the contention that carbon dioxide emissions from burning fossil fuels are the principal cause of global warming since 1970?

(Remember back in the 1970s, climate scientists and media were predicting a return to an “ice age.”)

I have posed that question to five “climate scientist” professors at the University of Arizona who claim that our carbon dioxide emissions are the principal cause of dangerous global warming. Yet, when asked the question, none could cite any supporting physical evidence.

Some of the professors would claim that computer models, when corrected for natural variation, required carbon dioxide emissions to correlate with observed warming of the late 20th Century. But computer modeling is not physical evidence; it is mere speculation. And correlation does not prove causation. One could easily substitute any increasing time series of data to produce similar results. In fact, an Australian group did a tongue-in-cheek exercise of comparing the historic price rise of a first class U.S. postage stamp with temperature. Results are shown on the graph below. The rise in the price of a stamp shows a remarkable correlation with the rise of global temperature.

In seeking an answer to the initial question, I also read the many reports from the UN Intergovernmental Panel on Climate Change. The reports provide no physical evidence, only various scenarios generated by computers. The outputs from computer models diverge widely from observational evidence because the models attribute too much warming influence to carbon dioxide emissions and too little to natural variation. (See Why Climate Models Run Hot by Rud Istvan.)

It appears that there is no physical evidence showing that carbon dioxide emissions have a significant effect on global temperature. There is, however, physical evidence showing that our carbon dioxide emissions are not having any significant effect, see my article Evidence that CO2 emissions do not intensify the greenhouse effect for details. That article examines four predictions made by climate alarmists of what we should see as atmospheric carbon dioxide content rises. In each case, what really happened was the opposite of what was predicted.

The benighted, eco-faddish, Tucson City council wants to reduce the City’s carbon footprint by installing 100 percent renewable energy for all city government operations so Tucson will not get as hot as Phoenix. (Source) If they do that, they really will be in the dark. In another article, Impact of Paris climate accord and why Trump was right to dump it, I present research which shows that even if all countries fulfilled their pledges to reduce carbon dioxide emissions made in the Paris Climate Accord, it would make a difference of only 0.17°C by the year 2100.

Can anyone provide an answer to the initial question?

Note: evidence of warming is not evidence of the cause of warming.

One other complication, Fake warming: A new peer-reviewed study finds that nearly all reported warming in the 20th century is a result of historic adjustments made to the original data. The study concludes: “The conclusive findings of this research are that the three GAST data sets [ Global Average Surface Temperature (GAST) data, produced by NOAA, NASA, and HADLEY] are not a valid representation of reality. In fact, the magnitude of their historical data adjustments, that removed their cyclical temperature patterns, are totally inconsistent with published and credible U.S. and other temperature data. Thus, it is impossible to conclude from the three published GAST data sets that recent years have been the warmest ever –despite current claims of record setting warming.” Read the study

Bottom line: Reducing carbon dioxide emissions will have little, if any, effect on global temperature. Such efforts are therefore a waste of money and other resources.

See also:

An examination of the relationship between temperature and carbon dioxide

Carbon dioxide is necessary for life on Earth

What keeps Earth warm – the greenhouse effect or something else?

Satellite data show that CO2 has almost no effect on global warming

Geology is responsible for some phenomena blamed on global warming

The past is getting cooler – an example of fake warming





  1. ROFL U.S. Postal charges – We should start a meme contest to see how many things correlate with climate change like that – just hilarious! Thank you!

    1. CarbonBrief misses the point. Evidence of warming is not the same as evidence of cause of the warming. Here are some comments by Dr. Roy Spencer of the UAH satellite system.

      Warming in the Tropics? Even the New RSS Satellite Dataset Says the Models are Wrong
      July 14th, 2017 by Roy W. Spencer, Ph. D.
      From recent media reports (e.g. the WaPo’s Capital Weather Gang) you would think that the new RSS satellite dataset for the lower troposphere (LT) has resolved the discrepancy between climate models and observations.
      But the new LT dataset (Version 4, compared to Version 3.3) didn’t really change in the tropics. This can be seen in the following plot of a variety of observational datasets and the average of 102 CMIP5 climate model simulations. (see URL below)

      Comparison of 102 CMIP5 climate model runs (average of 32 groups) against various observations for tropical lower tropospheric temperature anomalies during 1979-2016. All yearly time series were vertically placed so that their linear trends all intersect at zero, which is the proper way to display them to compare how much warming has occurred over the entire time period. The results were then displayed as running 5 year averages.
      It’s pretty clear that the models are producing too much atmospheric warming compared to satellites, radiosondes (weather balloons), and multi-observational atmospheric reanalyses. (And remember, the observations have a record warm El Nino at the end of the time series, which the model average does not. Without that, the discrepancy would be even larger).

      For those who claim, But humans live at the surface, not up in the atmosphere, do those same people ignore the warming of the deep oceans, too? Or maybe they will claim, But most people don’t live in the tropics — do those people worry about Arctic sea ice melting? (The Arctic Ocean covers 2.8% of the Earth, while the tropical results in the above plot are for 35.5% of the Earth).

      The fact is that how much warming is occurring in the troposphere (and in the deep oceans) tells us something about whether the climate models can be trusted. If their feedbacks are reasonably correct (which will determine how much global warming we should see in the future), the models should tell a reasonably consistent story in the atmosphere, in the ocean, at the surface, in the tropics, and outside the tropics.

      Remember, the climate models are the basis for energy policy changes, and so their quantitative projections are central to the case that we must do something about our greenhouse gas emissions.

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