Oliver Geden Profile picture
Mar 20 16 tweets 18 min read
After 3 yrs of hard work & a long approval plenary, we got the #IPCC #AR6 Synthesis Report published today, consisting of the Summary for Policymakers and a full report version ➡️ ipcc.ch/report/ar6/syr/
An ongoing 🧵, starting with SPM fig 1 on adverse climate change impacts
1/n
Every increment of warming matters (SPM.2)
#IPCC #AR6 #SYR
ipcc.ch/report/ar6/syr/
[2/n]
Future climate change to increase impacts and regional differences
#IPCC #AR6 #SYR
ipcc.ch/report/ar6/syr/
[3/n]
Risks are increasing with every increment of warming (SPM.4)
#IPCC #AR6 #SYR
ipcc.ch/report/ar6/syr/
[4/n]
Limiting warming to 1.5°C & 2°C involves rapid and deep GHG emission reductions (SPM.5)
#IPCC #AR6 #SYR
ipcc.ch/report/ar6/syr/
[5/n]
Rapidly narrowing window of opportunity to enable climate resilient development (SPM.6)
#IPCC #AR6 #SYR
ipcc.ch/report/ar6/syr/
[6/n]
Multiple opportunities for scaling up climate action (SPM.7)
#IPCC #AR6 #SYR
ipcc.ch/report/ar6/syr/
[7/n]
Focus on 1st day of #IPCC reports usually on Summary for Policymakers, a co-produced document leading to co-ownership that can't contradict findings in underlying report.
Approval plenary most visible aspect of #SciPol interface, but there're also review comments & responses
8/n
A full summary of the SPM can be found in the collection of "Headline Statements". The "Longer Report" hasn't been published yet, so we can't continue with its (many) figures for now. In the meantime, some SPM findings I was involved in
#IPCC #AR6 #SYR
ipcc.ch/report/ar6/syr/
9/n
Let's start with "Overshoot" (B.7), where I was responsible for drafting and 'negotiating' in plenary, but of course not alone (mainly together with @chrisd_jones, with whom I worked on corresponding section 3.3.4 in underlying report)
#IPCC #SYR
ipcc.ch/report/ar6/syr/
10/n
To understand the Overshoot bullet B.7, we need to start with B.1 on "Future Climate Change", led by @JuneYiLee1 & @sorensson_anna (who will hopefully correct me if I get something wrong).
#IPCC #AR6 #SYR
ipcc.ch/report/ar6/syr/
[10a/n]
The main overshoot-relevant message here: 1.5C probably reached (& exceeded) in 2030s, even in the most ambitious WG I and WG III scenarios
#IPCC #AR6 #SYR
ipcc.ch/report/ar6/syr/
[10b/n]
Scenarios aren't predictions when exactly 1.5C will be reached (& usually exceeded), but estimates given in footnote, pointing to first half of 2030s.
Important: '1.5C target' is abou multi-year averages, not individual years, to reach 1.5C even before
#IPCC #AR6 #SYR
[10C/n]
Summaries for Policymakers of both WG I (Aug 21) and WG III (Apr 22) reports already included these 2030s timeframes for 1.5C threshold reaching/crossing. Yet, the message did not really stick, neither in media nor in broader #climate (policy) community
#IPCC #AR6 #SYR
[10D]
The SPM text on the timeframes for 1.5C threshold reaching/crossing got a lot of attention in the approval plenary. You can get an impression by looking at the recently published @IISD_ENB report on the #IPCC #AR6 #SYR approval plenary
enb.iisd.org/58th-session-i…
[10E]
Btw, @IISD_ENB reports on #IPCC meetings provide very useful insights. But ENB observers are only allowed in plenaries, not in contact groups & huddles, where detailed deliberations take place. Government delegations certainly take this into account
enb.iisd.org/58th-session-i…
[10F]

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More from @Oliver_Geden

Mar 20
Unfortunately, the UN Secretary General still doesn't understand difference betw net-zero CO2 and much more ambitious net-zero GHG targets. The famous 2050 is net-zero CO2 for 1.5C, net-zero GHG only some decades later, as per #IPCC WG3 & Synthesis Report
politico.eu/article/climat…
UN Secretary General has been ill-advised by his own high-level expert group on net-zero, which also confuses net-zero CO2 and net-zero GHG.
It is all in the latest #IPCC reports, including the one released today. Why not just "listen to the science"?
Read 4 tweets
Jan 19
Today we publish the 1st edition of the "State of Carbon Dioxide Removal" report, a global assessment of the current #StateofCDR, and the gap we need to close to achieve the Paris temperature goal.
Full report➡️stateofcdr.org
An ongoing 🧵
[1]
This report compiles a first estimate of the total CDR being deployed (2 GtCO2/yr).
Almost all comes from "conventional" CDR on land, via afforestation, reforestation & forest management.
"Novel" methods don’t contribute much yet.
#StateofCDR
[2]
We provide a calculation of total gross CDR in #IPCC-assessed pathways to keep warming below 1.5C and 2C, including all methods. All pathways involve substantial cumulative CDR volumes (450-1100 GtCO2 by 2100) - in addition to immediate & deep emissions reductions
#StateofCDR
[3]
Read 35 tweets
Nov 8, 2022
The @UN #HLEGReport on Net-zero Emissions Committments is out
The problem though: #IPCC 1.5C pathways don't reach net zero GHG emissions by "2050 or sooner", but by the end of the century. The famous "net zero by 2050" (better "early 2050s) is CO2 only
un.org/en/climatechan…
1/
You might be in disbelief, but have a look at the #IPCC AR6 WG3 Summary for Policymakers, Table SPM.2:
For 1.5C with no or limited overshoot (category C1), pathways reach net-zero CO2 in 2050-2055, but net-zero GHG in 2095-2100
ipcc.ch/report/ar6/wg3…
2/n
The difference between net-zero CO2 and net-zero GHG can be explained by the dominant role of non-CO2 GHGs (methane, nitrous oxide, f-gases) in residual emissions and the dominant role of CO2 in removals
Read 14 tweets
Apr 11, 2022
➡️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
ipcc.ch/report/ar6/wg1…
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
ipcc.ch/report/ar6/wg1…
Read 6 tweets
Apr 4, 2022
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
[2/n]
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

[3/n]
Read 50 tweets
Apr 4, 2022
#IPCC #AR6 Working Group III SPM and Full Report on "Mitigation of Climate Change" is now available
ipcc.ch/report/ar6/wg3/
🧵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
ipcc.ch/report/ar6/wg3/
#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
ipcc.ch/report/ar6/wg3/
#ClimateReport Image
Read 9 tweets

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