In a new documentary, researchers investigate when Greenland was ice-free

[John Nissen]

In a new documentary, researchers investigate when Greenland was ice-free https://share.google/W6dUsy1itsnuTIE3m 

[John Nissen]

Here's support for our argument that GIS is melting away much faster than the modellers would admit, and there is a "grave risk of irreversibly melting off" [1].  To judge this risk, we need to look at what is causing the melting: high and rising temperature in the Arctic, driven mainly by a combination of albedo loss and atlantification.  To halt and reverse the melt, we need more cooling power than the heating power given by albedo loss and atlantification.  (A qualification on this is that there is some negative feedback from the Greenland meltwater and a weakening of the AMOC.)

Cheers, John

[1] https://phys.org/news/2023-07-greenland-years-high-sea-today.html

Extract:

Understanding Greenland's past is critical for predicting how its giant ice sheet will respond to climate warming in the future and how quickly it will melt. Since about 23 feet of sea-level rise is tied up in Greenland's ice, every coastal region in the world is at risk. The new study provides strong and precise evidence that Greenland is more sensitive to climate change than previously understood—and at grave risk of irreversibly melting off.

"Greenland's past, preserved in 12 feet of frozen soil, suggests a warm, wet, and largely ice-free future for planet Earth," says Bierman, a geoscientist in UVM's Rubenstein School of the Environment and Natural Resources and a fellow in the Gund Institute for Environment, "unless we can dramatically lower the concentration of carbon dioxide in the atmosphere."

[Tom Goreau]

Thanks, Rob! 

 

The key AI point, after the ritual “how wise you are to ask this question, master” stuff is:

 

• Orbital forcing + ice-sheet albedo set the timing and basic structure of the cycles.
• CO₂ and other GHGs provide a comparable chunk of the total temperature swing once feedbacks kick in. AGU Publications+1

 

Except it should say “MOST” not “a comparable chunk” the net amplification of the astronomical temperature effect by positive climate feedbacks is more than an order of magnitude!

 

But it is teleological to claim that these feedbacks are constantly optimizing, as in your Panglossian version of Gaia (which is NOT that of Lynn Margulis, long discussion for another time). While they tend to  do so over evolutionary time, species’ biogeochemical system interconnections are constantly being broken and reset by extreme stochastic events, such as plate tectonic volcanic eruptions, meteorites, fires, plagues, pestilences, and people. 

 

Human destabilization of the climate system by fossil fuels will likely cause an extremely low biodiversity world of weeds, pests, and parasites superbly adapted to decomposing each other in the worst of all possible worlds; a Runaway Hothouse that will take millions of years to flush its excess CO2 out of the system into carbon buried safely in sediments, and lower temperature to one safe for humans and almost all extant species not living in Hot Springs (which will be supremely happy at getting to dominate the world again after billions of years in exile).

 

Best wishes,

Tom

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