1/ 'At 412 ppm and rising, ...temperature rises of 3-4C are likely now locked in.
"It's like a crazy experiment: 'Let's take that CO2 that took 100 million years to be sequestrated and put it back—instantly, on a geological timescale—in the atmosphere and see what happens"
"It's like a crazy experiment: 'Let's take that CO2 that took 100 million years to be sequestrated and put it back—instantly, on a geological timescale—in the atmosphere and see what happens"
https://twitter.com/cohan_ds/status/1346301080272048128
2/ 'Earth has seen sustained concentrations of carbon dioxide was even higher than 400 ppm, but it took millions of years for those increases to occur.
Manmade greenhouse gas emissions, on the other hand, have boosted CO2 levels by more than 40% in a little over 150 years.'
Manmade greenhouse gas emissions, on the other hand, have boosted CO2 levels by more than 40% in a little over 150 years.'
3/ 'The last time that CO2 hit 400 parts per million (ppm) Greenland was ice free and trees grew at the edge of Antarctica.
..400 ppm was last surpassed 3 million years ago during the Late Pliocene, when temperatures were several degrees Celsius higher'..
..400 ppm was last surpassed 3 million years ago during the Late Pliocene, when temperatures were several degrees Celsius higher'..
4/ 'unless humans figure a way to suck CO2 out of the air on a massive scale, severe impacts are inevitable, sooner or later.' phys.org/news/2019-04-d…
5/ So how much global warming from greenhouse gases that have already been emitted is now 'baked in'?
Is 2C unavoidable? Is 3.5C unavoidable?
It depends how you define committed warming (see thread I quoted at the beginning) and also what assumptions are used in calculations 👇
Is 2C unavoidable? Is 3.5C unavoidable?
It depends how you define committed warming (see thread I quoted at the beginning) and also what assumptions are used in calculations 👇
6a/ James Hansen has indicated that over 405ppm puts us on course for +3.5°C
All journalists and editors should be investigating these discussions between scientists.
All journalists and editors should be investigating these discussions between scientists.
https://twitter.com/DavidLWindt/status/1346206815831412736?s=20
6b/ We're now seeing 415-418ppm of CO2 and emissions are still rising.
See this thread with articles including James Hansen's view:
See this thread with articles including James Hansen's view:
https://twitter.com/ClimateBen/status/1218534027965140992?s=20
7/ I started with the quote about our predicament being like an out of control scientific experiment because I think it describes well the disturbing uncertainties we face. Our understanding of the severity of deeply catastrophic global warming depends on various assumptions.
8/ Some scientists still cling to the fantasy of limiting warming to 1.5°C, whilst others see 3.5-4°C as essentially inevitable over centuries (and possible/likely over decades with continued emissions) at current CO2 concentrations.
This is being ignored by journalists.
Shame.
This is being ignored by journalists.
Shame.
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