Oliver Geden Profile picture
Sep 19, 2020 8 tweets 6 min read Read on X
A bit disturbing that #showyourbudgets contributes to ongoing confusion abt net-zero targets
Net zero CO2 ≠ net zero GHG ('climate neutral'), the latter reached 10-20 yrs later in scenarios due to harder-to-abate non-CO2, offset by CDR
National targets usually set in GHG not CO2
As you can see in global #IPCC pathways, most of the residual emissions at the time of net-zero (and later) are non-CO2, mainly methane and nitrous oxide from agriculture
swp-berlin.org/10.18449/2020R… Image
The same applies to the European Union's emissions trajectory towards net zero.
Residual emissions are to a large extent non-CO2 from agriculture
swp-berlin.org/10.18449/2020R… Image
In global 1.5C pathways, net zero CO2 is reached by 2050, net zero GHG by 2067 - so 17 years later!
The European Union's target of net zero emissions by 2050 is in GHG, not in CO2. I don't know of any EU country with an official CO2 reduction target
swp-berlin.org/10.18449/2020R… Image
This should be basic knowledge in the research community and among scientific advisors - but it obviously isn't
Even @sciforfuture Germany had to correct this point in their basic facts list (but it took some months to get them there...)
scientists4future.org/stellungnahme/… Image
Others, like @Umweltrat continue to add to the confusion
Here's already a good example how activists draw wrong conclusions from @showyourbudgets:
@KlimaVorAcht talks about 'linear GHG reduction paths', whereas #showyourbudgets figure only shows 'CO2 reduction paths'
I'd suggest that @showyourbudgets changes 'climate neutral' into 'carbon neutral' and makes clear how net-zero CO2 relates to standard GHG reduction targets.
In the meantime, just add 10-20 yrs to the numbers reported here, and maybe have a look at this
royalsocietypublishing.org/doi/full/10.10… Image

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More from @Oliver_Geden

Mar 31, 2023
As promised, now more on the topics I was deeply involved in as #IPCC #AR6 Synthesis Report author, both in the Summary for Policymakers & the so-called 'Longer Report':
overhoot, net zero, mitigation pathways (incl. CDR)

1/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 #AR6 #SYR
ipcc.ch/report/ar6/syr/
2/n
To understand the Overshoot SPM section B.7, we need to start with B.1 on "Future Climate Change", led by @JuneYiLee1 & @sorensson_anna
#IPCC #AR6 #SYR
ipcc.ch/report/ar6/syr/
3/n
Read 15 tweets
Mar 20, 2023
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
Mar 20, 2023
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]
Read 16 tweets
Jan 19, 2023
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

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