[MCN] Unsuitable for 'human life to flourish': Up to 3B will live in extreme heat by 2070, study warns

[Lance Olsen]

Global warming to push billions outside climate range that has sustained society for 6,000 years, study finds <https://news.google.com/articles/CBMiRmh0dHBzOi8vd3d3Lndhc2hpbmd0b25wb3N0LmNvbS93ZWF0aGVyLzIwMjAvMDUvMDQvaHVtYW4tY2xpbWF0ZS1uaWNoZS_SAVVodHRwczovL3d3dy53YXNoaW5ndG9ucG9zdC5jb20vd2VhdGhlci8yMDIwLzA1LzA0L2h1bWFuLWNsaW1hdGUtbmljaGUvP291dHB1dFR5cGU9YW1w?hl=en-US&gl=US&ceid=US%3Aen>
The narrow climate range that humanity has preferred for 6000 years is shifting poleward.
Washington Post
2 hours ago

Unsuitable for 'human life to flourish': Up to 3B will live in extreme heat by 2070, study warns <https://news.google.com/articles/CAIiELmIU9x9J2v3zxusd38MQz8qGQgEKhAIACoHCAowjsP7CjCSpPQCMM_b5QU?hl=en-US&gl=US&ceid=US%3Aen>
By 2070, up to 3 billion people are likely to live in climate conditions that are "warmer than conditions deemed suitable for human life to flourish."
USA TODAY <https://news.google.com/publications/CAAqBwgKMI7D-wowkqT0Ag?hl=en-US&gl=US&ceid=US%3Aen>
2 hours ago

PNAS first published May 4, 2020 
https://doi.org/10.1073/pnas.1910114117 <https://doi.org/10.1073/pnas.1910114117>

Future of the human climate niche
Chi Xu, Timothy A. Kohler, Timothy M. Lenton, Jens-Christian Svenning, and Marten Scheffer

Significance
We show that for thousands of years, humans have concentrated in a surprisingly narrow subset of Earth’s available climates, characterized by mean annual temperatures around ∼13 °C. This distribution likely reflects a human temperature niche related to fundamental constraints. We demonstrate that depending on scenarios of population growth and warming, over the coming 50 y, 1 to 3 billion people are projected to be left outside the climate conditions that have served humanity well over the past 6,000 y. Absent climate mitigation or migration, a substantial part of humanity will be exposed to mean annual temperatures warmer than nearly anywhere today.

Abstract

All species have an environmental niche, and despite technological advances, humans are unlikely to be an exception. Here, we demonstrate that for millennia, human populations have resided in the same narrow part of the climatic envelope available on the globe, characterized by a major mode around ∼11 °C to 15 °C mean annual temperature (MAT). Supporting the fundamental nature of this temperature niche, current production of crops and livestock is largely limited to the same conditions, and the same optimum has been found for agricultural and nonagricultural economic output of countries through analyses of year-to-year variation. We show that in a business-as-usual climate change scenario, the geographical position of this temperature niche is projected to shift more over the coming 50 y than it has moved since 6000 BP. Populations will not simply track the shifting climate, as adaptation in situ may address some of the challenges, and many other factors affect decisions to migrate. Nevertheless, in the absence of migration, one third of the global population is projected to experience a MAT >29 °C currently found in only 0.8% of the Earth’s land surface, mostly concentrated in the Sahara. As the potentially most affected regions are among the poorest in the world, where adaptive capacity is low, enhancing human development in those areas should be a priority alongside climate mitigation.

2004
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 More Intense, More Frequent, and Longer Lasting Heat Waves in the 21st Century. 

Gerald A. Meehl and Claudia Tebaldi. 
Science, 13 AUGUST 2004

2008
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"All organisms live within a limited range of body temperatures …. Direct effects of climatic warming can be understood through fatal decrements in an organism's performance in growth, reproduction, foraging, immune competence, behaviors and competitiveness."
 
Hans O. Pörtner and Anthony P. Farrell. Physiology and Climate Change. 
SCIENCE 31 OCTOBER 2008       VOL 322

2009
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"Observed heat wave intensities in the current decade are larger than worst-case projections."

Auroop R. Gangulya, et al. Higher trends but larger uncertainty and geographic variability in 21st century temperature and heat waves. 
PNAS, September 15, 2009.

2013
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“  … organisms have a physiological response to temperature, and these responses have important consequences …. biological rates and times (e.g., growth, reproduction, mortality and activity) vary with temperature.”
 
Anthony I. Dell, Samraat Pawar and Van M. Savage, Temperature dependence of trophic interactions are driven by asymmetry of species responses and foraging strategy.
Journal of Animal Ecology 2013 
   
1970  
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“What can be said with some assurance is that there is a unique and nearly ubiquitous compound, with the empirical formula H(2960)O(1480)C(1480)N(16)P(1.8)S, called living matter.  Its synthesis, on an oxidized and uncarboxylated earth, is the most intricate feat of chemical engineering ever performed - and the most delicate operation that people have ever tampered with.”

Edward S. Deevey, Jr.  Mineral Cycles. 
Scientific American, September 1970.

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