New #COP26 analysis: 🚨🌡️🌍
Is COP26 on track to keep 1.5°C alive?

Here I connect the dots between findings of the most recent scientific reports and look at what current pledges mean for carbon budgets limiting warming to 1.5C

(1/n)
I start with historical CO2 emissions from the Global Carbon Project @gcarbonproject as assessed in the latest @IPCC_CH #AR6 #ClimateReport

About 2400 billion tonnes of CO2 (GtCO2) have already been emitted between the years 1850 and the end of 2019 (2/n)
I then add global emissions pathways consistent with current policies, and various interpretations of country pledges (called NDCs, or nationally determined contributions) from the latest update of the @UNEP #EmissionsGap Report 2021. (3/n)

wedocs.unep.org/bitstream/hand…
The lowest, most optimistic pathway assumes that all conditions that countries include in NDCs are met, and all #NetZero are achieved.

(Note: the @UNEP report highlights that few 2030 targets are in line with meeting countries' long-term net zero targets at this stage) (4/n)
For the remainder of the analysis, I only work with this lowest, most optimistic pathway.

And compare the emissions under the curve with the remaining carbon budgets for limiting warming to 1.5°C from the latest @IPCC_CH AR6 #ClimateReport
(5/n)
ipcc.ch/report/ar6/wg1/
As it stands today, under the most optimistic pathway of #COP26 pledges and announcements, the carbon budget for keeping warming to 1.5°C with 50% or higher chance will be exhausted by the early 2030s.
(6/n)
What can be done?
What about increasing near-term ambition to ensure emissions are halved by 2030?

This postpones the date and is critical to keep 1.5°C alive, but action (and emissions reductions) cannot end there.

(7/n)
Only when further combined with the achievement of #NetZero CO2 emissions by 2050 can total CO2 emissions be kept to within a 1.5°C carbon budget.

Even then the likelihood that warming is kept to 1.5°C is barely about 50%. Not great, but keeping 1.5°C alive!

(8/n)
Uncertainties in past emissions, interpretations of pledges, and the size of carbon budgets do not change the core message that ambition needs to be increased to keep 1.5°C alive. (end)
With a big thank you to @RobinLamboll for helping to calculate these pathways!

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More from @JoeriRogelj

2 Nov
Often misunderstood, even by climate change scholars like @jasonhickel, a 2050 #netzero greenhouse gas emissions is not the global average!

It is two decades earlier than the global average in 1.5C pathways. (1/2)
1.5C pathways with no or limited overshoot reach #netzero CO2 emissions by 2050, and #netzero greenhouse gas emissions around 2070.

A target of #netzero GHG by 2050, like the EU, US, UK, and others, is thus well in advance of the global average.
This year's @UNEP #emissions report gives an overview of global timings of net zero CO2 and total greenhouse gas emissions.

Note the difference of about two decades between the timing of global #netzero CO2 and total GHG emissions. Image
Read 4 tweets
2 Nov
What makes a good #NetZero pledge?

Many things but picking three:
1) focus on reductions then removals (& separate them out)
2) justify how it is fair and adequate
3) have a clear plan showing how reductions are achieved in the near term (1/n)
bbc.com/future/article… @BBC_Future
Together with @CFyson from @climateactiontr and @katecullen_ we comment on how #NetZero targets can help, but also on how there is a series of boxes to be ticked by before any #NetZero target becomes a solid and ambitious contribution to tackling the #ClimateCrisis. (2/n)
Interested in more on #netzero targets?

I wrote a long thread on 10 guidelines that we published earlier this year in the scientific journal @Nature (with Annette Cowie, @ReisingerAndy and @Oliver_Geden) (3/n)

👇👇
Image
Read 4 tweets
26 Oct
The Heat is On🔥🌍
A world of climate promises not yet delivered

Today we’ve publish the @UNEP #EmissionsGap report

Good news:
we are doing increasingly better closing in on 2°C
Bad news:
it is still far from meeting the goals of the #ParisAgreement

A short thread (1/n)
The @UNEP #emissionsgap report takes stock of current pledges of countries and compares them to where emissions emissions should be going to limit warming to 1.5°C or 2°C.

The difference is called the emissions gap.
(2/n)
The latest @UNEP #EmissionsGap Report finds new and updated Nationally Determined Contributions only take 7.5% off predicted 2030 emissions compared to previous commitments. Reductions of 30% are needed to stay on the least-cost pathway for 2°C and 55% for 1.5°C. (3/n)
Read 15 tweets
19 Aug
Visuals in the latest #IPCCReport are a marvel I cannot stop talking about!

Here's part 2 of my overview of @IPCC_CH AR6 SPM visuals.

Kudos once again to @angelamorelli @tomhal99 @jordanharold and @MelichatGo for helping to visualize our insights (1/n)
After yesterday, we now landed on changes in extremes🌡️⛈️🥵🧺!

And although I don't like to pick favorites, I do like this visual very much.

Too big for a single tweet, this one shows how hot extremes over land change compared to when our great-grandparents were alive. (2/n)
Did you notice in the previous figure: a heat extreme that our great-grandparents would have experienced once in their lifetime, will occur about once every 4 years in a 2°C warmer world. It will be the norm in a 4°C warmer world.

I like the clarity of this figure! :)
(3/n)
Read 12 tweets
18 Aug
After the first bang of the @IPCC_CH AR6 report, it's time to look at my favorite part of the report:
visuals in the SPM.

It was a privilege to work with a team of #dataviz and information design experts @angelamorelli @tomhal99 @jordanharold on these visuals
(1/n)
The first visual shows us that human influence has warmed the climate at a rate unprecedented in at least 2000 years.

I really like how it contrasts the climate our societies were used to during their development with the evidence that we are responsible.
(2/n)
Read 12 tweets
9 Aug
Carbon budgets tell us how much CO2 we can still emit while keeping warming below specific limits.

The latest @IPCC_CH report provides updated estimates of these budgets.

Here’s an insider's view with a deep dive looking at how they have changed since previous reports. (1/n)
I have been involved in the estimation of carbon budgets since the IPCC Fifth Assessment Report in early 2010s.

And since the first IPCC estimates published in 2013, we have learned a lot and have gotten much better at estimating remaining carbon budgets. (2/n)
The scientific basis underlying a carbon budget is our robust scientific understanding that global warming is near-linearly proportional to the total amount of CO2 we ever emit as a society.

This is shown in Fig. SPM10, both for the past and future projections. (3/n)
Read 25 tweets

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