One of the major governance 'innovations' of #COP21 - agreeing on a >3°C deal while putting a 1.5°C label on it… Image
of course, there's the promise of 'ratcheting-up' pledges, and it remains to be seen if (or to what extent) it happens, but no, despite a lot of talk, the #ParisAgreement presents no legal obligation to do so…
then how can it even be possible to consider #1o5 still to be a feasible #climate target?
temperature overshoot (to be brought down by massive volumes of negative emissions) - probably not a particular hot topic next week [MT @WMO] Image
and finally, there is the overarching question of the size of the new remaining carbon budget, of course…
plus: &
#IPCC #SR15 Image

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More from @Oliver_Geden

Apr 11
➡️Only 6 out of 97 scenarios in the #IPCC #AR6 WG3 category C1 ('no to limited overshoot') never cross 1.5C
➡️91 out of 97 cross 1.5C temporarily, and then go back to 1.5°C by 2100

If you read the Summary for Policymakers of IPCC AR6 WG1 (Aug. 2021), this cannot come as surprise
Below the numbers from #IPCC #AR6 WG1. Not sure if this knowledge was conciously included in "keeping 1.5C alive and within reach" messaging around #COP26.
'Overshoot' pathways (= exceedance & return) didn't make it onto the high-level #UNFCCC agenda yet…
The overshoot logic might also a little bit hard to detect in this #IPCC #AR6 WG1 SPM figure. That's because overshoot is quite small (0.1°C) for SSP1-1.9, while at the same time all standard RCP levels (1.9-8.5) are shown in one figure…
Read 6 tweets
Apr 4
The #IPCC #AR6 WG3 report includes a comprehensive assessment of Carbon Dioxide Removal (CDR), its role in mitigation strategies and long-term pathways, but also a techno-economic assessment of ~10 CDR methods
An ongoing 🧵
[1/n] Image
For Carbon Dioxide Removal, it's still early days in #climate policy, although there are already established methods (mainly forestry-related and soil carbon sequestration, not necessarily done to remove CO2)
In #AR6 reports, there aren't chapters dealing solely with CDR
There was quite some CDR coverage already in the #AR6 Special Reports on 1.5°C (#SR15) and on land (#SRCCL). In WG I, CDR was mainly assessed in chapter 5 ('Biogeochemical Cycles'), and a bit in chapter 4

Read 45 tweets
Apr 4
#IPCC #AR6 Working Group III SPM and Full Report on "Mitigation of Climate Change" is now available
🧵on key figures and tables from Summary for Policymakers
#ClimateReport Image
Key figures & tables from the #IPCC #AR6 WG III Summary for Policymakers
SPM.1: Global net anthropogenic GHG emissions (GtCO2-eq yr-1) 1990–2019
#ClimateReport Image
Key figures & tables from the #IPCC #AR6 WG III Summary for Policymakers
SPM.2a: Regional GHG emissions, and the regional proportion of total cumulative production-based CO2 emissions from 1850–2019
#ClimateReport Image
Read 9 tweets
Mar 21
Today, we'll enter the long but final stretch for #IPCC #AR6 WG III report on mitigation - the virtual approval session, finalizing the 'Summary for Policymakers' (SPM) with governments Full Report and SPM to be published on April 4
Some insights...… [1/n]
First WG IIl lead author meeting took place 3 years ago, the process in itself way earlier. There've been delays because of #COVID19, but "Final Draft Report" has been submitted already in Nov 2021. The last months of work have been mainly about SPM…
There are strict confidentiality rules in the #IPCC when it comes to content, but as an intergovernmental organization, the #IPCC is quite transparent when it comes to process.…
Read 9 tweets
Oct 29, 2021
How will climate negotiators deal with diminishing carbon budget for 1.5C?
Some thoughts from our recent @OneEarth_CP paper "#UNFCCC must confront the political economy of net-negative emissions"
Now available #OpenAccess for 2 months… #COP26
Basic problem is quite easy to understand. We're very close to 1.5C, and even if you think it's still possible to stay within the remaining carbon budget (<500 Gt), this would mean that every country needs to reach net zero pretty soon.
Read 10 tweets
Oct 29, 2021
Remarkable framing shift ahead of #COP26

While "close to 1.5C" is politically more plausible than "limit to 1.5C", it's quite ambiguous, similarly to already established "well below 2C"

Is this the new language incorporating (initial) overshoot of 1.5C?…
Some background on #IPCC WG1 projections for threshold 1.5C crossing times under different scenarios, explained by @hausfath for @CarbonBrief…
"Constructive ambiguity" is a useful tool to reach agreement under #UNFCCC. But problematic that #ParisAgreement doesn't exclude or at least sets clear constraints for 1.5C overshoot. Creates way too much flexibility
See our 2017 @NatureGeosci piece #COP26
Read 4 tweets

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