Joeri Rogelj Profile picture
climate scientist | 1.5°C, net zero, carbon budgets, climate justice | director of research @Grantham_IC | lead author @UNEP #emissionsgap, @IPCC_CH SR15 & AR6
RadReduction (Larry Edwards) Profile picture 1 added to My Authors
Feb 7 12 tweets 3 min read
Excellent conversation going on about how media messaging following the @IPCC_CH 1.5 report sating we have "12 years left" until [your favorite climate pandemonium term] has been a disservice to science communication, and is damaging to date 👇
(1/n) @guardian @Fridays4future As one of the coordinating authors of the report I can only wholeheartedly agree with @bobkopp @PFriedling @theresphysics and others that this is a dangerous misrepresentation of the report's assessment and messages.

Let me explain why

Nov 30, 2021 9 tweets 5 min read
Two years ago - we published a new scenario logic to avoid risky and unfair climate change scenarios in @Nature.

Yesterday, two new studies in @NatureClimate apply this logic and find that avoiding overshoot is the right thing to do both to reduce risks and overall costs.
Our initial @Nature study highlighted that focussing on a target in 2100 and not caring about what happens until then results in scenarios that suggest the best way to meet a target is to plan to first miss it.

Weird, irresponsible, and arguably wrong.
Nov 13, 2021 11 tweets 3 min read
#COP26 is concluding after two years of work with some important decisions.

Some highlights of those areas I have followed most closely:
1) science
2) increased ambition
3) the Paris Rulebook

Some quick reflections (1/n) 1) science
For the first time ever, scientific evidence is included as a key framing of the various COP decisions. This is historic and includes strong messages on the scientific requirements as identified by @IPCC_CH to keep warming to 1.5C.
Nov 10, 2021 10 tweets 6 min read
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)
Nov 2, 2021 4 tweets 3 min read
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.
Nov 2, 2021 4 tweets 4 min read
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_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)
Oct 26, 2021 15 tweets 10 min read
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.
Aug 19, 2021 12 tweets 6 min read
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)
Aug 18, 2021 12 tweets 5 min read
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.
Aug 9, 2021 25 tweets 6 min read
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)
May 27, 2021 8 tweets 5 min read
EXPLAINER: new projections for the next 5 years by @metoffice and @WMO indicate that there's a high chance that one of these years is 1.5°C warmer than average preindustrial levels.

What does this mean?
A short explainer.


(1/n) The 1.5C level in the @metoffice announcement should not be confused with the 1.5C limit in the Paris Agreement.

The Paris targets refer to global warming - that is, the temperature increase of our planet once we smooth out important year-to-year variations (see👇)
May 18, 2021 11 tweets 6 min read
*Great NEWS*
Today @IEA published its #NetZero2050Roadmap-a scenario that brings global CO2 emissions down to #NetZero by 2050.

This is the first time IEA presents a detailed picture of how the global economy can be transformed in line with 1.5C (1/n)… A detailed look at the report shows that @IEA has done a thorough job.

Modelling choices underpinning the pathway are well argued, reliance on speculative technologies is limited, and the carbon budget is in line with the most ambitious pathways available in the literature (2/n)
Mar 31, 2021 14 tweets 8 min read
Today's news from Australia's @Science_Academy latest climate report: "limiting climate change to 1.5°C is now virtually impossible"

I'm quite confused by their finding & scientific evidence backing it up is questionable at best.

- a thread (1/n)… The @Science_Academy's analysis starts from carbon budgets reported in @IPCC_CH's 1.5°C Special Report's Table 2.2 (orig. below).

Then makes adjustments & updates.

Having had the pleasure to compile Table 2.2 for #SR15, let's compare and try to make sense of the numbers

Mar 17, 2021 17 tweets 11 min read
How can #NetZero targets be made rigorous, fair and transparent?

We published 10 guidelines that can help

Details are buried in the supplement of our @nature comment.

Here I'll be going through them, one per day

@COP26 @topnigel @PEspinosaC


The supplement contains an overview table (👇) and a detailed set of guidelines for #NetZero targets

They cover:
I. Scope (of target)
II. Adequacy & Fairness
III. Long term roadmap

It's a long list - so let's get through it one day at a time

(2/n)… Image
Mar 16, 2021 21 tweets 14 min read
what are #NetZero targets?
why do they matter?
and why do vague targets lull the world in missing its climate goals?

A (long) thread with scientific and policy background on our recent @nature commentary

#ClimateScience @NatureNews… What are #NetZero targets?

#NetZero targets are key benchmarks towards a world where we avoid the worst of climate change. But if defined vaguely, they leave a lot of wiggle room and can compromise achievement of the #ParisAgreement

We provide guidelines to avoid this.

Mar 16, 2021 6 tweets 4 min read
"Net-zero emissions targets are vague: three ways to fix"
In a new @Nature piece we explain how countries & companies can set rigorous, fair and transparent net-zero targets.

Thread (1/n)

With @Oliver_Geden, @CowieAnnette & @ReisingerAndy
(@NatureNews)… Countries and companies around the world are declaring net-zero targets - all in their own way, often in vague terms, and mostly without considering what it means for others or where it leads to. (2/n)
Oct 15, 2020 8 tweets 4 min read
Solving the #ClimateCrisis too expensive?
Think again.

#COVID19 recovery stimulus dwarfs green energy investment needs for a 1.5°C-compatible world

A thread on our new scientific analysis published in @ScienceMagazine In the wake of the economic crisis caused by the #COVID19 pandemic, governments have pledged unprecedented amounts of economic recovery and stimulus.

We tally up all pledges and compare them to what we would need to transform the global energy system to #netzero by 2050 (2/n)
Sep 19, 2019 11 tweets 9 min read
THREAD: In a new study in @nature we present a way to avoid the bias that burdens future generations and the risky strategies that current #climate change mitigation pathways suffer from.

A #climatetwitter explainer

#Fridays4Future #ClimateStrike #ParisAgreement

(1/n) Existing #ClimateChange scenarios focus on reaching a target in 2100

but by doing so weirdly suggest that the best way to achieve a #climate target is to delay action first, miss it over the next decades, and then to try to make up for it later