Theory vs. Evidence: the great climate debate


GHGs: Over the last century, mankind's activities -- mainly fossil fuel use -- have increased atmospheric CO2 from about 0.03% of the Earth's atmosphere to just over 0.04% (400 ppmv) today.

Theory: Increased “greenhouse gas” (GHG), levels, mainly carbon dioxide (CO2) will cause dramatic, destructive increases in the Earth’s temperature, in sea-level rise, and in severe weather events.

Evidence: The worrisome negative effects of anthropogenic CO2 are merely theoretical. The benefits of anthropogenic CO2, however, are saving millions of lives, already.

The warming from anthropogenic GHGs is modest and benign. When ENSO and volcanic aerosols are taken into account there’s been very little warming in the 21st century [Santor, Schmidt, et al 2014, Volcanic contribution to decadal changes in tropospheric temperature. Nature Geoscience, 7: 185–189].

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Worldwide storminess actually seems to have decreased slightly, rather than increased, as greenhouse gas levels have gone up. Hurricanes & tropical cyclones have no clear trend, and tornadoes are trending down:   

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Sea level rise has been essentially linear for nine decades, and with little or no effect from elevated CO2:

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Every high-quality, long-term coastal sea-level measurement record in the world shows the same thing: adding >100 ppmv of CO2 (and ~1 ppmv CH4) to the atmosphere has not significantly affected sea-level rise.


The benefits of higher CO2 levels are important and well-documented. 15-20% of current agricultural productivity is directly due to the beneficial “fertilization” effects of anthropogenic CO2. 

About 40% of the Earth's land is used for agriculture. So we can calculate that without anthropogenic CO2, 47%-50% of the Earth's land would need to be devoted to agriculture, to make up for the loss of productivity, i.e., 10-15 million km² of land.

Unfortunately, much of the Earth's land is not suitable for agriculture, with a very notable exception: rainforests. Rainforests cover about 9 million km² of the Earth's surface. If CO2 were at pre-industrial levels (about 0.028%), then cutting down all the world's rainforests and converting them to agriculture would almost make up for the lost of agricultural productivity due to lack of anthropogenic CO2.

Here's a picture from a very old issue of Scientific American, showing the effect of anthropogenic carbon dioxide on crops. Scientific American called anthropogenic CO2 “the precious air fertilizer.”

1. Yield of potatoes in fields over which the air was fertilized with carbonic acid gas and left unfertilized.

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Anyone who cares about starvation and poverty (and anyone who cares about the Earth's rainforests!) should be thankful that mankind's use of fossil fuels has raised atmospheric CO2 from about 0.03% of the atmosphere (a century ago) to the current 0.04%. That’s why I and 31,486 other American scientists (including engineers in relevant specialties) have signed the Global Warming Petition, signifying our agreement with this statement:

“There is no convincing scientific evidence that human release of carbon dioxide, methane, or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth's atmosphere and disruption of the Earth's climate. Moreover, there is substantial scientific evidence that increases in atmospheric carbon dioxide produce many beneficial effects upon the natural plant and animal environments of the Earth.”


From the “Climategate” leaker’s “readme” manifesto:


“Over 2.5 billion people live on less than $2 a day.”

“Every day nearly 16000 children die from hunger and related causes.”

“One dollar can save a life” -- the opposite must also be true.

“Poverty is a death sentence.”

“Nations must invest $37 trillion in energy technologies by 2030 to stabilize greenhouse gas emissions at sustainable levels.”

Today's decisions should be based on all the information we can get, not on hiding the decline.


Dave Burton       M: 919-244-3316         October 9, 2017

NC Sea Level Rise Impact Study Advisory Committee member, U.N. IPCC AR5 WG1 Expert Reviewer, NC-20 Science Advisor.

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