[MCN] Meanwhile, what can we expect for the young when the heat rises to 3-4C hotter than 1850?

[Lance Olsen]

Excerpt : In his forthcoming book, Our Final Warning <https://www.harpercollins.co.uk/9780008308599/our-final-warning-six-degrees-of-climate-emergency/>, Mark Lynas explains what is likely to happen to our food supply with every extra degree of global heating. He finds that extreme danger kicks in somewhere between 3C and 4C above pre-industrial levels. At this point, a series of interlocking impacts threatens to send food production into a death spiral. Outdoor temperatures become too high for humans to tolerate <https://www.thelancet.com/journals/lanplh/article/PIIS2542-5196(18)30240-7/fulltext>, making subsistence farming impossible across Africa and South Asia. Livestock die from heat stress. Temperatures start to exceed the lethal thresholds <https://www.cbd.int/financial/2017docs/usa-climateagro.pdf> for crop plants <https://www.cbd.int/financial/2017docs/usa-climateagro.pdf> across much of the world, and major food producing regions turn into dust bowls <https://epic.uchicago.edu/wp-content/uploads/2019/07/nplants2016193.pdf>. Simultaneous global harvest failure <https://www.pnas.org/content/115/26/6644> – something that has never happened in the modern world – becomes highly likely.

In combination with a rising human population, and the loss of irrigation water, soil and pollinators <https://www.theguardian.com/environment/2019/jun/19/us-beekeepers-lost-40-of-honeybee-colonies-over-past-year-survey-finds>, this could push the world into structural famine. Even today, when the world has a total food surplus, hundreds of millions are malnourished as a result of the unequal distribution of wealth and power. A food deficit could result in billions starving. Hoarding will happen, as it always has, at the global level, as powerful people snatch food from the mouths of the poor. Yet, even if every nation keeps its promises under the Paris  <http://paris-equity-check.org/warming-check>agreement <http://paris-equity-check.org/warming-check>, which currently seems unlikely, global heating will amount to between 3C and 4C.

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“Our sweat-based cooling mechanism is crude; beyond a certain combination of high temperature and humidity, it fails. To be outside and exposed to such an environment for any length of time soon becomes a death sentence.

“And that environment is spreading. A death zone is creeping over the surface of Earth, gaining a little more ground each year. 

As an analysis published this week in Nature Climate Change shows, since 1980, these temporary hells on Earth have opened up hundreds of times to take life (C. Mora et al. Nature Clim. Change http://dx.doi.org/10.1038/nclimate3322 <http://dx.doi.org/10.1038/nclimate3322>; 2017). At present, roughly one-third of the world’s population lives for about three weeks a year under such conditions. If greenhouse-gas emissions continue to rise unchecked, that figure could climb, exposing almost three-quarters of the population by the end of the century.

“The analysis also reveals that even aggressive reductions in emissions will lead the number of deadly heatwaves to soar in the coming decades. Cities including London, New York, Tokyo and Sydney have all seen citizens die from the effects of excessive heat. By 2100, people in the tropics could be living in these death zones for entire summers. It’s true that warmer winters will save lives further north. And those living in urban environments may find ways to adapt to the new norm of extreme heat. 

“But, if the researchers are correct, the politics of Pruitt and those who try to hold him to account will seem quaint and anachronistic to our grandchildren. For they will live in a world in which most will see the environment less as something to protect, and more as something to protect themselves and their families from.”

Nature 546, 452 (22 June 2017) doi:10.1038/546452a

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