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Glen Peters Profile picture
@Peters_Glen
Sep 9, 2020 โ€ข 3 tweets โ€ข 1 min read โ€ข Read on X
The Paris Agreement aims to hold "the increase in the global average temperature to ๐ฐ๐ž๐ฅ๐ฅ ๐›๐ž๐ฅ๐จ๐ฐ ๐Ÿยฐ๐‚ above pre-industrial levels & ๐ฉ๐ฎ๐ซ๐ฌ๐ฎ๐ข๐ง๐  ๐ž๐Ÿ๐Ÿ๐จ๐ซ๐ญ๐ฌ to limit the temperature increase to ๐Ÿ.๐Ÿ“ยฐ๐‚..."

Which of the SR15 scenario categories meet that criteria? Image
A few points:
* Does "lower 2ยฐC" or "upper 2ยฐC" qualify as "well below 2ยฐC"?
* Are scenarios that never go above 1.5ยฐC too extreme (ie, scenarios that exceed the aims)
* What to do with the peak & decline profile (which has consequences on large-scale carbon dioxide removal)?
Data from the #SR15 scenario database data.ene.iiasa.ac.at/iamc-1.5c-explโ€ฆ

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More from @Peters_Glen

Glen Peters Profile picture
Apr 12
There is a very strong linear relationship between atmospheric CO2 (concentration) and cumulative CO2 emissions.

In the last days, quite a few have been commenting there are feedbacks kicking in.

A thread...

1/ Image
If atmospheric CO2 is proportional to cumulative CO2 emissions, then the annual change in atmospheric CO2 is proportional to annual CO2 emissions.

The ratio of the two is the 'airborne fraction', which is rather constant. Maybe a slight increase in trend lately, maybe...

2/ Image
Since emissions have leveled out in the last decade, one would expect therefore that the atmospheric increase has leveled out.

The concentration data is noisy, and it has leveled out or not depending on how it is smoothed! (look at last 10 years).

3/ Image
Read 8 tweets
Glen Peters Profile picture
Apr 9
Is the atmospheric growth rate of CO2 slowing down?

Total CO2 emissions have gone from 2%/yr growth (2000s) to 0%/yr (2010s).

Do we see that change in the atmosphere?

It is hard to answer ๐Ÿงต



1/ rdcu.be/buifD
Image
I can make this figure incredibly complex by adjusting for ENSO (red dots and line).

We know the response of atmospheric CO2 to El Niรฑo is lagged. This figure shows a 9 month lag, as used by Betts & Jones in their projection

But, 2023 is a La Niรฑa?

2/ metoffice.gov.uk/research/climaโ€ฆ
Image
The same figure with a three month lag says 2023 is a El Niรฑo.

In either case, adjusting the growth rate for ENSO makes it look like the atmospheric CO2 growth rate is maintained, and not slowing down.

This is worrying. It should be slowing down...

3/ Image
Read 8 tweets
Glen Peters Profile picture
Dec 15, 2023
One of the key arguments that Norway uses to continue oil & gas developments, is that under BAU it is expected that oil & gas production will decline in line with <2ยฐC scenarios, even with continued investment.

Let's look closer at these projections & reality...

1/ Image
Here is the projections from the 2003 report from the petroleum agency.

In reality (tweet 1) there was a dip around 2010, but production is now up around 250 million cubic again.

The forecast was totally & utterly WRONG!

2/ Image
In 2011 there was a forecast for an increase in production to 2020, but then a decline. This is probably since they started to put the Johan Sverdrup field on the books.

The increase in production was way too low, again, they got it wrong.

3/ Image
Read 9 tweets
Glen Peters Profile picture
Dec 5, 2023
๐Ÿ“ขGlobal Carbon Budget 2023๐Ÿ“ข

Despite record growth in clean energy, global fossil CO2 emissions are expected to grow 1.1% [0-2.1%] in 2023.

Strong policies are needed to ensure fossil fuels decline as clean energy grows!



1/ essd.copernicus.org/articles/15/53โ€ฆ
Image
CO2 emissions by fossil fuel:
* We thought coal peaked in 2014. No, & up another 1.1% in 2023
* Oil up 1.5%, on the back of a 28% increase in international aviation & China, but oil remains below 2019 level. ๐Ÿคž
* Has the golden age of gas come to an end thanks to Russia?

2/ Image
By top emitters:
* China up 4.0% & a peak this year would be a surprise
*US down 3.0%, with coal at 1903 levels
* India up 8.2%, with fossil CO2 clearly above the EU27
* EU27, down 7.4% with drops in all fuels
* Bunkers, up 11.9% due to exploding international aviation

3/ Image
Read 11 tweets
Glen Peters Profile picture
Nov 3, 2023
Is the new @DrJamesEHansen et al article an outlier, or rather mainstream?

At least in terms of the key headline numbers, it seems rather mainstream, particularly if you remember most headline key numbers have quite some uncertainty!



๐Ÿงต1/ academic.oup.com/oocc/article/3โ€ฆ
Image
Equilibrium Climate Sensitivity of 4.8ยฐC ยฑ 1.2ยฐC

IPCC best estimate 3ยฐC
IPCC likely range: 2.5-4ยฐC
IPCC very likely range: 2-5ยฐC

Sure, Hansen et al are in the high end, but so are many others.

More details:

2/
Image
"...global warming will exceed 1.5ยฐC in the 2020s & 2ยฐC before 2050"

Here is the global warming from "Current Policies" in IPCC AR6 WGIII. Sorry folks, but Hansen is actually conservative.

Also, cast your eyes to 2020-2030: WARMING ACCELERATES

3/ Image
Read 7 tweets
Glen Peters Profile picture
Oct 31, 2023
The Remaining Carbon Budget for 1.5ยฐC is now smaller because:
1) We have not reduced emissions in three years
2) Updated simple climate models because of updated historical aerosol emissions
3) Some new method choices



1/ nature.com/articles/s4155โ€ฆ
Image
The update for 2ยฐC has similar changes for each component, but because the budget is much bigger, the changes don't seem that dramatic. Not Nature Climate Change worthy...

The changes to the 1.5ยฐC budget seem dramatic, because the budget is basically gone.

2/ Image
These updates are not new. A few years back 1.5ยฐC was considered "geophysically impossible", but not after a revised budget:


I wrote a post on the utility of 1.5ยฐC budgets back then, obviously ignored. Also on non-CO2.


3/ nature.com/articles/ngeo3โ€ฆ
rdcu.be/0Tiv
Image
Read 5 tweets

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