HistoPol (#HP) 🏴 🇺🇸 🏴
#CO2 has historically shown a much higher climate sensitivity
(1/n)
via #AlisonGeorge
"...the 👉 last time #CO2 levels were consistently as high as they are today was around 14 million years ago – considerably longer ago than some previous estimates...👈
Today’s climate models estimate that a doubling of atmospheric CO2 levels would result in warming of b/w 1.5°C and 4.5°C. But the 👉 results suggest a much bigger temperature rise: ...
Michael E. Mann :verified:
Ancient climate analysis suggests CO2 causes more warming than thought" by Alison George for @newscientist https://newscientist.com/article/2407270-ancient-climate-analysis-suggests-co2-causes-more-warming-than-thought/
[but--as I note, higher climate sensitivity for past hothouse climates likely doesn't apply to current warming]" #OurFragileMoment
HistoPol (#HP) 🏴 🇺🇸 🏴
(2/n)
...
...it doesn’t tell us what global temperatures are likely to be in 2100. “There’s a sluggish, cascading effect that slowly kicks in,” says Hoenisch...
...climate sensitivity may have been different at other times in Earth’s history compared with now,...
“In short, the estimates of climate sensitivity from this study are probably not applicable to current human-caused warming,” says Mann."
Maybe. Almost all of us will live to see it,...
HistoPol (#HP) 🏴 🇺🇸 🏴
(3/n)
...if what more and more scientists believe to be true:
via #MichaelLePage:
"Major climate tipping points could be triggered 👉 within a decade👈
The climate has warmed so much that we are already at risk of triggering five global “#TippingPoints” that would have catastrophic effects worldwide and 👉couldn’t be reversed easily if at all, according to a major report.👈
“Triggering one tipping point could trigger another in a kind of dangerous domino...
HistoPol (#HP) 🏴 🇺🇸 🏴
(4/n)
...effect,” says #TimLenton at the #UniversityOfExeter in the #UK, the report’s lead author. “But also 👉these tipping points in the Earth system could, in turn, trigger damaging tipping points in societies,👈 things like food security crises, mass displacement [#ClimateRefugees] and conflicts. Stopping these threats is possible, but it’s going to require urgent global action.”
"...the five major tipping points we are near to crossing are: ...
HistoPol (#HP) 🏴 🇺🇸 🏴
(5/n)
...
•the loss of the #Greenland ice sheet,
•the demise of the West #Antarctic #IceSheet,
•the die-off of tropical #CoralReefs,
the abrupt thaw of large areas of #Arctic #permafrost and
•the slowing of an ocean current known as the #NorthAtlanticSubpolarGyre."
"Other #TippingPoints include the die-off of #seagrass meadows and #mangrove forests, and the collapse of #fisheries."
"For some tipping points, we have a very short window for preventive...
HistoPol (#HP) 🏴 🇺🇸 🏴
(6/n)
...action open right now which might close as soon as the 2030s,..."
"“[The slowing of the subpolar gyre] 👉could happen within about 10 years,”👈 says #McKay. “It would have pretty major impacts across both sides of the #Atlantic. It would 👉cause regional cooling and affect agriculture in #Europe and #NorthAmerica👈 , and change the patterns of extreme weather events.”
"...it still isn’t clear which systems have #TippingPoints, how close we are...
HistoPol (#HP) 🏴 🇺🇸 🏴
(7/n)
...to crossing them..."
“Even with a profound acceleration of action, some Earth system tipping points may be unavoidable,” says #Lenton."
And maybe one final thought:
ALL prevalent #ClimateModels have erred on the low side so far.
//
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