Felix Schaumann

Is "overshoot" replacing "tipping points" in the climate discourse?

I wrote a short blog post exploring this idea.

Bottom line: it's all about urgency and irreversibility, but overshoot can circumvent some problems that the tipping points framing has.

Read the full post here: s.gwdg.de/wRWft8

🚨 We are hiring! I am looking for a postdoc to join my team at the… | Rupert Stuart-Smith 🚨 We are hiring! I am looking for a postdoc to join my team at the University of Oxford, working on a Wellcome Trust-funded project on climate change and health. The post will run until February 2028....

🚨 We are hiring! I am looking for a climate scientist postdoc to join my team at Oxford working on a project on climate change and health until Feb 2028. For more details: www.linkedin.com/feed/update/...

📅 Apply by 14 May here: my.corehr.com/pls/uoxrecru...

YouTube video by MaxPlanckSociety Billionen Kosten durch schwächere Meeresströmung | Wissen Was News

[Video] AMOC-Schwächung könnte Billionen kosten. Die #AMOC-Abschwächung verringert die #CO₂-Aufnahme, verstärkt die Erderwärmung & erhöht die Kosten - so die neue Studie von @felixschaumann.bsky.social & @edualastrue.bsky.social (MPI für Meteorologie). Carolin Riethmüller fasst für Euch zusammen➡️🔗

Thanks a lot! We look at the global ocean, so we didn't check whether AABW might counteract this, but the net effect is to recuce carbon uptake. The main difference to LGM studies is that we have emissions scenarios, so the downwelling water is relatively more carbon-rich than the upwelling water.

Overview of the modeling approach. (A) The Max Planck Institute Earth System Model is used to simulate climate states with an artificially weakened Atlantic Meridional Overturning Circulation (AMOC). (B) The resulting changes in annual ocean carbon storage are then analyzed as a function of the simulated AMOC. (C) The strength of the AMOC carbon feedback is estimated until 2100. (D) The economic impact of these projected changes is then analyzed.

Climate change could weaken the Atlantic Meridional Overturning Circulation (AMOC), which would cool the Northern Hemisphere. A weaker AMOC could also diminish ocean carbon uptake, thus increasing the social cost of carbon. In PNAS: www.pnas.org/doi/10.1073/...

Economic impact studies tend to find a weaker AMOC globally beneficial, as lower temperatures in the Northern Hemisphere would offset some global warming & associated economic damages - but new paper shows this ignores reduced C uptake by oceans & Social Cost of Carbon. See bsky.app/profile/feli...

AMOC: Eine kleine Wahrscheinlichkeit, dass etwas sehr Schlimmes passiert Der Kollaps einer Meeresströmung könnte Europa extrem kalte Winter wie in Kanada bringen, warnten Forschende zuletzt. Unwahrscheinlich, sagt eine neue Studie. Was stimmt?

Der Kollaps einer Meeresströmung könnte Europa extrem kalte Winter wie in Kanada bringen, warnten Forschende zuletzt. Unwahrscheinlich, sagt eine neue Studie. Was stimmt?

Check out this great paper by @felixschaumann.bsky.social with @edualastrue.bsky.social out now in @pnas.org that integrates climate science with climate economics to study the social cost of carbon implications of reduced AMOC weakening. Super impressive work for a first PhD chapter👇

thanks!

Weaker ocean current could cost trillions Faculties

💰 Weaker ocean circulation may cost trillions

A new study by @felixschaumann.bsky.social and @edualastrue.bsky.social in @pnas.org reveals that a weakening Atlantic Meridional Overturning Circulation (AMOC) could lead to costs of several trillion euros. #CLICCS #climate #ocean @uni-hamburg.de

No cheers for warming slowdown from potential weakening of AMOC given carbon drawdown impact. New study.

Die Abschwächung der #AMOC bietet neben den bereits oft prognostizierten Abkühlungseffekten für Nordeuropa weitere spannende Skills: Sie wird wohl auch die CO2-Aufnahmekapazität des Nordatlantiks verringern.
#Klimakrise #Nordatlantik #Ozean #Ozeanographie

[11/11]

Of interest? @ayeshatandon.carbonbrief.org @daisydunne.carbonbrief.org @klimareporter.bsky.social @fionaharvey.bsky.social @jonathan-watts.bsky.social @dpcarrington.bsky.social @muellerjung.bsky.social @sventitz.bsky.social @jonaswaack.bsky.social @fischblog.bsky.social @revkin.bsky.social

[10/11]

📖 If you are still curious, check out the news items by the CEN research center @cenunihh.bsky.social of the University of Hamburg @uni-hamburg.de and the Max Planck Institute for Meteorology (mas.to/@MPI_Meteo@w...).

[9/11] Where to go from here?

With one more impact channel of AMOC weakening - probably not the most relevant - the picture already changes quite a bit.

A lot of other impacts remain, and we should research them if we want to properly understand the risks that are associated with a changing AMOC.

Relative SCC changes due to AMOC temperature effects and AMOC carbon effects in comparison.

[8/11]

The SCC is raised by about 1% because of the AMOC carbon feedback (right panel).

This is of similar magnitude, but of opposite sign, to the previous economic impact estimates of AMOC weakening (left panel):

[7/11] What do we find? Economic impacts

Looking at the additional (Burke) economic damages induced by this feedback, we estimate numbers in the range of trillion US dollars, cumulated over this century.

But the more important economic indicator is the social cost of carbon (SCC).

CMPI6 projections of AMOC strength and the associated ocean carbon storage reductions in 2100.

[6/11]

But the cumulative effect for this century is - depending on the projection of AMOC strength - between 4 and 12 PgC.

For context: Every year we emit around 10 PgC, so by 2100, AMOC weakening could reduce ocean storage by up to a full year of current emissions to the atmosphere.

Scatter plot of carbon flux changes over AMOC strength with a linear regression line.

[5/11] What do we find? Carbon cycle impacts

We find that, in a year with a 1 Sv weaker AMOC, 0.023 PgC less will flow into the ocean. That doesn't sound like much, maybe 0.2% of current anthropogenic CO2 emissions.

Overview of our methodology in 4 steps.

[4/11] How do we do it?

Our methods in a cartoon:

a) freshwater hosing in a biogeochemically-only coupled ESM
b) yearly carbon flux changes as a function of yearly AMOC strength
c) cumulative carbon flux reductions in the 21st century following CMIP6 AMOC projections
d) changes in SCC estimates

[3/11]

But what about all the other climate impacts that AMOC weakening would have, beyond just surface temperatures?

They have yet to be integrated into economic impact assessments, and we start by looking at the carbon cycle.

[2/11] Why is this relevant?

Existing economic impact estimates deem AMOC weakening globally beneficial. Why?

Because a weaker AMOC would reduce temperatures in the Northern Hemisphere and thereby locally offset parts of global warming and the associated economic damages.

🚨 First PhD paper in @pnas.org 🥳

🌊 @edualastrue.bsky.social and I looked at how much less CO2 will be taken up by the ocean if the #AMOC weakens - and how this reduced ocean carbon uptake affects the social cost of CO2 emissions.

📝 Read the paper here: doi.org/10.1073/pnas...

🧵 A thread [1/11]

Synthesis of evidence yields high social cost of carbon due to structural model variation and uncertainties | PNAS Estimating the cost to society from a ton of CO2—termed the social cost of carbon (SCC)—requires connecting a model of the climate system with a re...

Excited to announce a new @pnas.org publication on the Social Cost of Carbon. We integrate evidence from the literature and expert survey to provide an SCC distribution inclusive of both parametric and structural uncertainties. Our mean 2020 value is $283 per ton CO2
www.pnas.org/doi/10.1073/...

In a new interdisciplinary Nature Climate Change Perspective paper, led by me, @lisgilmore and Rachael Shwom, we offer a critical perspective on #climate and social “tipping points.” 🎁: rdcu.be/d2gBC 🧵

fair-calibrate v1.4.1: calibration, constraining, and validation of the FaIR simple climate model for reliable future climate projections Abstract. Simple climate models (also known as emulators) have re-emerged as critical tools for the analysis of climate policy. Emulators are efficient and highly parameterised, where the parameters a...

The model calibration paper for fair is now published in Geoscientific Model Development! 🎉

TLDR: how do we constrain a highly parameterised model to observational and assessed constrained ranges, with uncertainty?

gmd.copernicus.org/articles/17/...

There are so many cool starter packs around here 💙 But I have not seen yet any specifically on the AMOC, so I decided to create one now 🌊 Let me know if you want to be included too!

#AMOC #Atlantic #OceanCirculation

go.bsky.app/JxFDh6b

Countries could use nature to ‘cheat’ on net zero targets, scientists warn By relying on natural carbon sinks such as forests and peatlands to offset emissions, governments can appear closer to goals than they actually are

Softening the definition of Net Zero won’t stop global warming. As authors of the 2009 “Net Zero Papers” we call on countries and companies to recognise the need for Geological Net Zero, balancing flows of carbon into and out of the Earth’s crust.
www.theguardian.com/environment/...

go.bsky.app/7PReUyF

#AcademicSky

Maybe dealing with GPTs hallucinating papers should give us a reason to update our 20th century approaches to article referencing. Can't we just use the DOI when writing papers and stop pretending that anybody is going to go to a physical library to find a specific journal volume?