Saturday, September 15, 2018
Abrupt Climate Change
written 8 Sep 2018
published 15 September 2018
Radio Curious (www.radiocurious.org) recently posted two interviews with Guy McPherson, about abrupt climate change producing human extinction within a decade, updating information from 3 years ago. McPherson represents an extreme position on this subject, but even if his timing is in error, the science of the unfolding events is solid.
With the president denying man made climate change, it is comforting to believe that if there is a problem, the effects are decades away. To protect profits, fossil fuel corporations continue to spend millions of dollars creating doubt about the science. Reality ignores these political and economic fantasies.
For almost a million years, the planet went through a series of ices ages, broken by warmer periods, called inter-glacial. The average Earth temperature during the last ice age was 12°C, which warmed to 13.5°C for the current inter-glacial, during which human civilizations arose. Since 1750, CO2 emitted by industrial activity has warmed the Earth to 15.25°C. We have changed the Earth temperature more than the difference between an ice age and the present inter-glacial period. The steady addition of atmospheric CO2 increases the temperature slowly, but other forces in motion are massively non-linear, with abrupt consequences.
The most sensitive area is the Arctic Ocean basin, which has been covered in ice for most of human existence. The Arctic is warming 3-5 times faster than the rest of the planet, and minimum coverage in summer has declined 75% since 1980. In 1984, 61% of Arctic ice was multi-year ice, crunched into thick, dense ridges, and resistant to melting. This year only 34% is multi-year ice, and only 2% is over 5 years old. Last month, warming winds broke up the oldest ice, and much of it moved into the Atlantic, causing iceberg problems in the shipping lanes.
Open water warms more quickly because the darker water absorbs sunlight and heat the white ice used to reflect. Without a protective ice cover, storms mix the water, transporting heat deeper into the ocean, which slows ice growth the following winter.
While climate models predict an ice-free Arctic summer in the mid 2040s, current warming trend suggests an Arctic ice-free summer by the early 2030s. In an interview podcast on September 4th (www.tucradio.org), Arctic scientist Peter Wadhams said Arctic warming is accelerating, and an ice-free summer could happen in the next few years.
This is worrisome, because the Arctic basin is shallow, with a large Russian continental shelf less than 150' deep. Buried on that shelf are 1-10 trillion tons of frozen methane, a short-lived greenhouse gas almost 100 times more potent than CO2. A release of only 50 billion tons, a tiny fraction of what is there, would raise the Earth temperature .6°C within a few years.
As long as there is ice in the water, the ocean can't get much warmer than freezing, but an ice-free Arctic would quickly warm, and a massive methane release could happen at any time, which has scientists very worried. This temperature spike would heat the Arctic first, releasing even more methane, a tipping point for thermal runaway. Methane plumes are increasing, from none in mid-1990s to 150,000 in 2012, indicating thawing of the Arctic seafloor has begun.
In addition to more wildfires, rapid temperature increase threatens humans in two ways. We are exothermic beings, giving off heat as a result of our biochemistry. We cool our bodies through evaporation. When the combination of temperature and humidity is too high evaporation becomes impossible, our vital organs cook, and we die. Some areas of the planet hit this lethal heat each year, and thousands die. With more heating, more territory will be uninhabitable by people or animals.
The crops we depend on, primarily wheat and rice, die when the temperature gets too high. The current warming is already causing local crop failures and contributing to the rising cost of food. A large, rapid temperature increases would devastate global agriculture, leading to wide spread starvation and migration, and probable economic collapse.
At a recent conference in Rome, convened to advise the Pope on climate issues, world famous physical oceanographer, Walter Munk, was asked for his solution to the climate challenge. He said it would take a miracle and involve love.