GLOBAL CARBON BUDGET 2021 🧵

After dropping 5.4% in 2020, global fossil CO₂ emissions are expected to increase 4.9% [4.1-5.7%] in 2021, finishing just 0.8% below 2019 emission levels.

globalcarbonproject.org/carbonbudget/i…

1/
Coal & gas are now back above their pre-pandemic (2019) levels, while oil remains suppressed.

Assuming oil returns to 2019 levels in the next year or two, a drop in coal use is required to avoid further emissions growth.

2/
China grew in 2020 & especially 2021, now with solid growth since 2016.

Other major countries had a rebound which puts them back on their decade trends.

The recovery is also uneven across smaller countries (all others).

3/
Our projections are the hard work of @robbie_andrew & @jikorsbakken, who use monthly energy data to estimate emissions & then project forward for the months without data.

This means we have estimates by coal, oil, gas, & cement for major emitters.

4/
This year there was a major update of CO₂ emissions from land-use change, mainly in Brazil.

Land-use change emissions now trend downwards in the last decade instead of trending upwards in the earlier budgets (dotted line).

5/
In the @gcarbonproject, we update all the data every year (come on, seriously, you think we just add an extra year?).

With the new land-use data, total emissions are now flat in the last decade.

6/
The revised LUC data does not help keep RCP8.5 alive, unfortunately (?).

Now total CO₂ emissions are clearly deviating from high-end emission pathways (this was not the case previously).

More here: nature.com/articles/d4158…

7/
All these CO₂ emissions lead to an increase in the atmospheric concentration of CO₂, which are estimated to reach 415 parts per million (ppm) this year.

@robbie_andrew uses available observational data & projects for the rest of the year using the seasonal cycle.

8/
In the last decade, the atmospheric CO₂ increase has averaged ~2.4ppm.

Even though emissions dropped 5.4% in 2020, CO₂ increased 2.4ppm.

In 2021 emissions went up 4.9%, but CO₂ may increase only 2.0ppm.

Why? rdcu.be/buifD

/9
Understanding the year-to-year changes in the carbon cycle is why we update carbon budget annually.

We now also project all components of the budget to the current year!

This baseline historical data is critical to help improve future modelling, like in @4C_H2020

10/
This thread is only a flavor of the global carbon budget:
* Find links to all the resources here: globalcarbonproject.org/carbonbudget/i…
* All the figures & data here tinyurl.com/GCB21figs

Thanks to the almost 100 colleagues for the hard work!

11/11
PS: Don't worry, I will tweet more in the coming days, weeks, months, years, ...

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More from @Peters_Glen

5 Nov
You may have heard that after revisions to land-use change emissions, total global CO₂ emissions are approximately flat over the last decade (black line).

But, how much do we revise carbon budget components each year?

Let's have a look...

1/
Fossil CO₂ emissions are revised each year, particularly the last decades. We update data & improve methods. Chinese data has had major revisions & cement was completely revised in 2018, plus lots of smaller improvements.

More details: zenodo.org/record/5569235

2/
Land-use change (LUC) emissions are much more uncertain:
* 2014-2015: one bookkeeping model used
* 2016-2019: two bookkeeping models used
* 2020-2021: three bookkeeping models used
* 2021: major update of land-use forcing (change) datasets

Uncertainty remains high! Beware!

3/
Read 10 tweets
2 Nov
"Everyone wants to keep the dream of 1.5°C alive. In every practical sense you are kidding yourself if you think that we are remotely heading towards 1.5°C"

So why the optimism? #COP26

businessgreen.com/feature/403897…

1/
The world has made progress from where we were 10 years ago (2010), but on the “current policy scenario” emissions will continue to rise.

According to UNEP EGR, emissions will remain flattish to 2030, if governments implement the necessary policies.

unep.org/resources/emis…

2/
The UNFCCC Synthesis Report says NDCs will lead to a 5% rise in emissions from 2019 to 2030. This is 16% above 2010 levels, as opposed to ~50% below as required for <1.5C.
unfccc.int/news/updated-n…

3/
Read 7 tweets
14 Oct
THREAD🧵

Is it time to move beyond net zero emissions & start discussing net negative emissions?

Why? To allow developing countries to reach net zero later (fairness) & help them escape poverty while still limiting warming to 1.5°C.

@aniruddh_mohan sciencedirect.com/science/articl…

1/
The carbon budget for 1.5°C is depleting rapidly, with a large share used by today’s developed countries.

Even if developed countries mitigate fast, the carbon space remaining for developing countries is minuscule.

(also see cicero.oslo.no/no/posts/cicer…)

2/
If global CO₂ emissions stay at net zero, either:
* All countries need to be net zero ~2050, or
* Rich countries have net negative emissions post-2050, allowing developing countries to emit longer post-2050.

3/
Read 12 tweets
13 Oct
Did you know that 30% of cumulative CO₂ emissions are from land-use change?

If the starting point is 1750 or earlier, this share just goes up.

essd.copernicus.org/articles/12/32…

1/ Image
Another factoid. Half of global CO₂ emissions in 1950 were from land-use change. That is not so long ago!

The declining share of land-use change in the total is not because the world ended deforestation, but coal, oil, & gas grew.

2/ Image
CO₂ emissions from land-use change are incredibly uncertain. Uncertainty is 50% or more.

There are also definition issues in what is defined as anthropogenic (what is a carbon sink?).

3/ Image
Read 5 tweets
8 Oct
"Instead of leaving such work to volunteers, global institutions should marshal the funding & expertise to collect crucial data, & mandate their publication"

💯agree with @_HannahRitchie. No one wants to fund the giant who's shoulders we stand on.

1/

nature.com/articles/d4158…
The approach to science is to fund big models, expensive observations, etc. All this is needed, but somehow science seems to have forgotten the importance careful curation & maintenance of data.
2/
Science is full of projects that improve models, do model comparisons, process some satellite data, etc, & if you are lucky there might be a task that scrapes together some data to feed the models.
3/
Read 10 tweets
7 Oct
It is a top day for a top ten day...

We often do plots of the top emitters, especially for fossil CO₂ emissions. But, what about other GHGs? Is it the same distribution of top emitters?

We need a thread for that...

(I know about per capita, so no need to @ me)

1/
CO₂ emissions from net LUC (one bookkeeping model). These are net numbers, some countries are net sources, others net sinks.

Current LUC sources are concentrated in several developing countries (the rich countries cut their forests down long ago).

2/

agupubs.onlinelibrary.wiley.com/doi/full/10.10…
Don't over interpret the LUC numbers.

Different LUC datasets give different numbers. Here is the FAO data (from 2020). Indonesia is much less important in this dataset, Brazil dominates.

There is a lot of uncertainty at the country level, so be careful.

3/
Read 10 tweets

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