📢Global Carbon Budget 2024📢

Despite some predicting a peak in global fossil CO2 emissions, we estimate growth of 0.8% [-0.3% to 1.9%] in 2024. Maybe a peak next year?

Is it all bad news, or can we find some good news?

1/ We estimate EU emissions down 3.8%, US edged down 0.6%, & Chinese emissions edged up 0.2%.

Emissions were up strongly in India 4.6% & international aviation 13.5%.

The record growth in renewables is helping bend the curve, just not enough to get a peak in global emissions.

2/

I am still pondering over 2023 & El Nino. Is 2023 an (unusual) outlier or not?

Looking at anomaly in 2023 relative to the trendline (loess 50 year window), without (left) & with (right) annualised ENSO lags, then 2023 is rather mundane.

1/

When looking at the temperature change relative to the previous year, without (left) & with (right) annualised ENSO lags, then 2023 is more unusual depending on the lag.

If 2023 is unusual, then it could be equally explained by 2022 being low (rather than 2023 being high).

2/

I started to take an interest in the 2023 temperature increase...

The first plot I did, to my surprise, seems to suggest that 2023 is not unusual at all (given El Nino).

Why?

1/ It all depends on how you slice the data. The previous figure was the anomaly relative to a trend (loess with 50 year window).

If I plot the change from the previous year (delta T), then 2023 is more unusual. Though, still, is it 2023 that is unusual, or 2022, or 2016, or?

2/

Has the land sink collapsed in 2023?

I am not so convinced. The land sink has a lot of variability, mainly due to El Nino, and an El Nino overlapped 2023. So we expect a lower land sink in 2023.

(My estimate assumes the ocean sink was average).

1/ Was 2023 an El Nino year? That is not so obvious...

How does one average the monthly sea surface data to an annual value El Nino index? How does one account for the lag between El Nino and the change in atmospheric CO2 growth?

There is no unique answer to this.

2/

Nitrous Oxide (N2O) is no laughing matter, atmospheric N2O has increased 25% due to human activities.

Today @gcarbonproject updates the Global Nitrous Oxide Budget, which helps us understand where the N2O comes from and where it goes.



1/ essd.copernicus.org/articles/16/25…
According to IPCC AR6, N2O caused 0.1°C of the current warming of 1.1°C (not this figure is now higher).

This may sound small, but since N2O is long-lived (like CO2) & primarily comes from agriculture, that 0.1°C will only go up in the future.

2/

Greenhouse gas emissions are at record highs, again.

The only good news is that Ozone Depleting Substances (ODS) regulating under the Montreal Protocol have declined substantially in the last decades.

But what does all this mean for climate?



1/ 🧵 essd.copernicus.org/articles/16/26…
Record high emissions means record high radiative forcing.

We have you covered, we also include aerosols (SO2, etc) & have done so for decades. Also shipping!

Short-lived aerosols are important, but should not distract from the drivers of change: greenhouse gas emissions!

2/

"Implemented policies result in projected emissions that lead to warming of 3.2°C, with a range of 2.2°C to 3.5°C (medium confidence)"

According to the landmark, widely reported IPCC Synthesis Report published in 2023.


1/ ipcc.ch/report/ar6/syr/
If you are surprised by this figure, where the median is 2.5°C (not 3.2°C), then I am curious why you think scientists are so optimistic...

The survey reflects more or less what scientists have been saying for years?



2/ theguardian.com/environment/ar…

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/ 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/

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 🧵



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

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

But, 2023 is a La Niña?

2/ metoffice.gov.uk/research/clima…

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 <2°C scenarios, even with continued investment.

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

1/ 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/

📢Global Carbon Budget 2023📢

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/15/53…
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. 🤞
* Has the golden age of gas come to an end thanks to Russia?

2/

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!



🧵1/ academic.oup.com/oocc/article/3…
Equilibrium Climate Sensitivity of 4.8°C ± 1.2°C

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

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

More details:

2/

https://twitter.com/hausfath/status/1720098321161957761?t=3qr7fL1lsk857U8KJ8BLZw&s=03

The Remaining Carbon Budget for 1.5°C 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/s4155…
The update for 2°C 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 1.5°C budget seem dramatic, because the budget is basically gone.

2/

ATTENTION

What is one of the most important decisions in climate science?

The selection of scenarios that will dominate climate research for the next 7+ years.

So, we wrote a perspective...

Here is the preprint:

1/ gmd.copernicus.org/preprints/gmd-…
To illustrate the importance, here is ScenarioMIP from CMIP6/AR6!

This is where SSP5-85 is chosen, & in fact, "considered the highest priority".

Where is SSP1-19, perhaps the most important scenario in climate policy? It was 'forced' in afterwards!



2/ gmd.copernicus.org/articles/9/346…

My father was born in 1921 & it warmed 1°C in his life, but his life improved immensely in 100 years.

The world is on track (currently) to warm another 1°C in 100 years, does that mean a kid born in 2021 will have (similar) improvements in life?

Bold thinking. But why?

1/

https://twitter.com/oneill_bc/status/1699072996516962812

I think the first paragraph of Brian's article highlights a problem.

First, reference 6, @OurWorldInData does not support this statement, only the last phrase.

Second, our current modelling framework simply cannot answer the question, & is arguably unable to.

2/

To get to net zero CO2 emissions in 2050, the @IEA laid out a range of key milestones. There is so much work to do, in so many sectors. We know what to do.

There is also some Carbon Dioxide Removal. The IEA had ~2GtCO2 removed & stored, different to the 7.6GtCO2 'captured'.

1/ The IEA has key pillars:
* energy efficiency
* behaviour (yes, even the IEA)
* electrification
* renewables
* hydrogen
* bioenergy
* CCUS

An industry like steel will have measures in all these pillars.

2/

The scenarios assessed by the IPCC achieve short-term emission reductions (2020-2030) through ~75% decline in coal use. Oil & gas only have moderate declines between 2020 & 2030.

What are the equity implications?

1/ By 2050, basically all coal is gone (~100% reductions), and any coal that remains has CCS (not shown explicitly in the figure).

Oil & gas have only declined ~50% by 2050.

2/

I updated my 'stylised pathways' to 1.5°C figure to include coal, oil, & gas. Here is an example which shares the remaining budget 30:30:30:10 to coal, oil, gas, other.

In this presentation I play with those ratios a little bit:
linkedin.com/posts/glen-pet…

1/ To make it easier to compare, this is what it looks like for each individual fossil fuel with those assumptions.

I have not calibrated these to scenarios from IAMs, but that is an obvious next step.

2/

I find the narrative "we need BOTH emission reductions AND carbon dioxide removal" increasingly problematic.

We need emission reductions. Full stop. Period. End of story.

Here is another attempt to show why emission reductions must come first & be prioritised.

1/ "But we need to invest in CDR now to get the necessary scale in 2050".

Sure, so invest if you must. But your investment is pointless unless emission reductions happen. So, if you want to get a payback from your investment, you need to make emission reductions happen.

2/

"Drastically reduce emissions first, or carbon dioxide removal will be next to useless" writes @_david_ho_

nature.com/articles/d4158…

1/ CDR is in addition to all the hard work reducing emissions from coal, oil, gas, cement, steel, etc. It is not instead of...

Yes, yes, you all know this. In fact, everyone knows this, but CDR has still captured everyone's imagination. Why? Because they don't know!

2/

An update of my 'stylised pathways' figure showing the the implications of exhausting the remaining carbon budget without net negative CO₂ emissions (dark brown) compared to using overshoot (light brown).

The overshoot component is what we ask future generations to do...

1/ This particular configuration overshoots the remaining carbon budget by 270GtCO₂, which is about 0.12°C.

That small amount requires at least 270GtCO₂ carbon dioxide removal & likely more because of the need to counterbalance the 'hard-to-abate' emissions.

2/