[Vision2020] 8-6-18 Proceedings of the National Academy of Sciences: Disastrous 'hothouse Earth, ' climate scientists warn

[Ted Moffett]

News article on PNAS paper lower down.
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http://www.pnas.org/content/early/2018/07/31/1810141115
Trajectories of the Earth System in the Anthropocene
Will Steffen, Johan Rockström, Katherine Richardson, Timothy M. Lenton, Carl
Folke, Diana Liverman, Colin P. Summerhayes, Anthony D. Barnosky, Sarah E.
Cornell, Michel Crucifix, Jonathan F. Donges, Ingo Fetzer, Steven J.
Lade, Marten
Scheffer, Ricarda Winkelmann, and Hans Joachim Schellnhuber
PNAS August 6, 2018. 201810141; published ahead of print August 6, 2018.
https://doi.org/10.1073/pnas.1810141115
Abstract

We explore the risk that self-reinforcing feedbacks could push the Earth
System toward a planetary threshold that, if crossed, could prevent
stabilization of the climate at intermediate temperature rises and cause
continued warming on a “Hothouse Earth” pathway even as human emissions are
reduced. Crossing the threshold would lead to a much higher global average
temperature than any interglacial in the past 1.2 million years and to sea
levels significantly higher than at any time in the Holocene. We examine
the evidence that such a threshold might exist and where it might be. If
the threshold is crossed, the resulting trajectory would likely cause
serious disruptions to ecosystems, society, and economies. Collective human
action is required to steer the Earth System away from a potential
threshold and stabilize it in a habitable interglacial-like state. Such
action entails stewardship of the entire Earth System—biosphere, climate,
and societies—and could include decarbonization of the global economy,
enhancement of biosphere carbon sinks, behavioral changes, technological
innovations, new governance arrangements, and transformed social values.



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https://www.oregonlive.com/trending/2018/08/were_well_on_the_way_to_disast.html

We're well on the way to disastrous 'hothouse Earth,' climate scientists
warn in new study

By Douglas Perry <http://connect.oregonlive.com/user/dperry/posts.html>

dperry at oregonian.com

The Oregonian/OregonLive

Longer, hotter heatwaves. Larger and more frequent wildfires. Less snowpack
and water reservoirs that remain stubbornly low.

We're already seeing the results of a warming planet. But we probably
haven't seen anything yet, scientists continue to warn.

A new study found that the planet could be heading toward a "hothouse
Earth" scenario in which natural feedback loops -- such as massive methane
release from melting permafrost -- would crank up the warming of the planet
to disastrous levels. If this happens, even the ending of fossil-fuel
emissions wouldn't arrest it.

"If the threshold is crossed, the resulting trajectory would likely cause
serious disruptions to ecosystems, society and economies," states the
study, titled "Trajectories of the Earth System in the Anthropocene."

The paper is published in PNAS
<http://www.pnas.org/content/early/2018/07/31/1810141115> (Proceedings of
the National Academy of Sciences of the United States of America).

"These tipping elements can potentially act like a row of dominoes,"
Stockholm Resilience Center executive director and study co-author Johan
Rockstrom said
<https://www.independent.co.uk/environment/climate-change-hothouse-earth-global-warming-rainforests-sea-ice-heatwave-a8479706.html>
this week. "Once one is pushed over, it pushes Earth towards another. It
may be very difficult or impossible to stop the whole row of dominoes from
tumbling over."


The conventional wisdom in the scientific community is that global warming
of about 2 degrees Celsius
<https://www.cnn.com/2018/08/07/health/hothouse-earth-warming-intl/index.html>
above pre-industrial levels could be the tipping point for the climate,
causing unstoppable warming up to 5C -- "a much higher global average
temperature," the study notes, "than any interglacial in the past 1.2
million years." Right now, the Earth is a little over 1C above the
pre-industrial period.

The study is not all doom and gloom. Possible solutions, it states, include
"decarbonization of the global economy, enhancement of biosphere carbon
sinks, behavioral changes, technological innovations, new governance
arrangements and transformed social values."

-- Douglas Perry

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Vision2020 Post: Ted Moffett
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