Read on Twitter
*Another* great @Peters_Glen thread.
A specific tweet↓prompts a small tangent from me re: a simple detail most ongoing discussions of "1.5°C!" seem to casually skip over:
"remaining carbon budget... from SR1.5 𝙖𝙛𝙩𝙚𝙧 𝙙𝙚𝙙𝙪𝙘𝙩𝙞𝙣𝙜 3 𝙮𝙚𝙖𝙧𝙨"
https://twitter.com/Peters_Glen/status/1361227700158009346?s=19
A specific tweet↓prompts a small tangent from me re: a simple detail most ongoing discussions of "1.5°C!" seem to casually skip over:
"remaining carbon budget... from SR1.5 𝙖𝙛𝙩𝙚𝙧 𝙙𝙚𝙙𝙪𝙘𝙩𝙞𝙣𝙜 3 𝙮𝙚𝙖𝙧𝙨"
https://twitter.com/Peters_Glen/status/1361227700158009346?s=19
Maybe it's obvious &/or implied in various current "discussions" about favoured pathways to 1.5°C (or "well-below" 2°C).
I don't sense it.
IPCC SR1.5 remaining CO₂ budgets are calculated↓from end-*𝟮𝟬𝟭𝟳*. We *already* need to deduct ~127 GtCO₂ emissions of subsequent 3yrs
I don't sense it.
IPCC SR1.5 remaining CO₂ budgets are calculated↓from end-*𝟮𝟬𝟭𝟳*. We *already* need to deduct ~127 GtCO₂ emissions of subsequent 3yrs
So, applying that delta↑by rote, the "66% and 50% chances of 1.5°C" SR1.5 carbon budgets have already been reduced from 420 to 293 GtCO₂ (-30%), and from 580 to 453 GtCO₂ (-22%), respectively. (best estimates, ±,...)
In fact, Matthews, et al., 2021,↓,...
In fact, Matthews, et al., 2021,↓,...
... reworked post-2020 budgets, using updated TCRE calculations, finding best estimates for "66% and 50% chance of 1.5°C" budgets of just 230 and 440 GtCO₂, respectively. https://www.nature.com/articles/s43247-020-00064-9
Substituting either "deduct 3 years of emissions from SR1.5 budgets" or "Matthews 2021 recalculation" into the plot below↓from Matthews, et al., 2020, (which, presumably by convention, still used the SR1.5 budget of post-2017, i.e. 420 GtCO₂), and the "blue" line...
... which circumscribes the "no-negative emissions, straightline reduction, 66% chance at below 1.5°C" budget, would no longer hit zero *global* emissions in 2040, but rather in ~2035 or 2032, respectively. Halving during 2027 or 2026.
"Challenging." https://www.nature.com/articles/s41561-020-00663-3
"Challenging." https://www.nature.com/articles/s41561-020-00663-3
Adjust with either the 2018-2020+ actual emissions or new estimates, and similar dynamics/crunch are at play for the remaining carbon budget if you relax either the temperature objective and/or likelihood of staying below it.
My point simply being that some "discussions"...
My point simply being that some "discussions"...
... in favour of, or, more often, opposed to a particular mitigation technology sometimes seem detached from or unaware of how fast the carbon budgets associated with the temperature targets they advocate for are tightening in real-time, and how even more demanding they are if...
... certain options are arbitrarily (or otherwise) excluded. It's simply the math.
Just saying.
And for no particular reason, I'll sign off sharing two "quotes".
"Time waits for no one, no favours has he
Time waits for no one, and he won’t wait for me."
Just saying.
And for no particular reason, I'll sign off sharing two "quotes".
"Time waits for no one, no favours has he
Time waits for no one, and he won’t wait for me."
And something I heard Robert Socolow say in a session roughly 10 years - and 400 GtCO₂ of emissions! - ago:
"What is safe is no longer fair. And what's fair is no longer safe."
He was specifically talking about the inter- and intranational equity of... https://www.mdpi.com/2071-1050/4/2/210
"What is safe is no longer fair. And what's fair is no longer safe."
He was specifically talking about the inter- and intranational equity of... https://www.mdpi.com/2071-1050/4/2/210
... emissions reductions...
But 400 GtCO₂ of emissions later, it is equally instructive about some of the awkward, reluctant compromises and sacrifices we will have to make if we are serious about rapidly getting to net zero emissions and stabilizing temperatures.
But 400 GtCO₂ of emissions later, it is equally instructive about some of the awkward, reluctant compromises and sacrifices we will have to make if we are serious about rapidly getting to net zero emissions and stabilizing temperatures.
