The Andy May Paper on Climate Change (1)

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(No German translation of this post)

For future reference — perhaps: a two-part series in which Andy May summarises what we know or rather do not know about puported human induced global warming (Climate Change, due to Solar Variability or Greenhouse Gases? Part A.) and natural variability (Climate Change, due to Solar Variability or Greenhouse Gases? Part B.). He seems to conclude: we know — in the phrase of my former economics professor — very nearly bugger-all about the causes of climate change.

Among the many gems to be found in these papers, I liked this one in particular:

Clearly the Earth has been warming for the past 150 years or so, the warming could be natural or human-caused or both. Will it continue warming until dangerous temperatures are reached? Newell and Dopplick (Newell and Dopplick 1979) and Sud, et al. (Sud, Walker and Lau 1999) have pointed out that evaporation from the oceans limits maximum average atmospheric temperatures to 303K (30°C or 86°F). 

Evaporation stores latent energy (heat) in water vapor that is released when the water vapor cools and precipitates as liquid water. The water vapor can be transported great distances, often in clouds, before the precipitation occurs and the heat is released. This process of evaporation, convection and precipitation is the primary mechanism for cooling the surface of the Earth according to (Pierrehumbert 2011), (Benestad 2016) and others. 

Thus, as long as the oceans exist, it is highly unlikely dangerous temperatures will be reached on Earth (Miskolczi 2014).

Christopher Scotese has compiled a detailed reconstruction of Earth surface temperatures for the past 550 million years (Scotese 2015). The Earth’s surface average temperature has been as warm as 28°C in the past and as cold as 12°C. The average surface temperature over the last 550 million years is around 20°C (68°F), some 5°C warmer than today. 

At no time in the Earth’s past do we see average temperatures that exceed 30°C, which agrees with the conclusions of Newell and Dopplick and Sud, et al.

And this comment by a certain Eustace Cranch: 

as long as the oceans exist, it is highly unlikely dangerous temperatures will be reached on Earth

I think “highly unlikely” is a vast understatement. The Earth has had 4 billion years or so of opportunity, under wildly varying atmospheric compositions, yet thermal runaway has never occurred.

Q: What’s so special about right now? A: Nothing.

The source. 

Continued here.