Joeri Rogelj

⚖️Climate litigation is entering a new era 🌏

Thanks to attribution science, courts now have the tools to link climate impacts, such as floods, wildfires and extreme heat to major polluters — and assign legal responsibility. 🧵

📒 imperial.ac.uk/stories/polluters-on-trial

Implications of states’ dependence on carbon dioxide removal for achieving the Paris temperature goal Achieving the Paris Agreement’s long-term temperature goal of limiting global warming well below 2°C while pursuing efforts to limit it to 1.5°C requires rapid and sustained reductions in greenhous...

www.tandfonline.com/doi/full/10....

New research on limits to CO2 removal (CDR). CDR is key to our ambition to stop adding climate pollution to the atmosphere. Because it's uncertain how much will be delivered and it clearly comes with risks of social & environmental side-effects, legal issues arise. This paper provides an overview. 👇

⛈️ @frediotto.bsky.social reviewed extreme weather, such as the LA wildfires, to show that climate change is outpacing adaptation efforts.

🎯 @joerirogelj.bsky.social warns that passing the 1.5°C goal only intensifies the legal & ethical obligations of the Paris Agreement.

buff.ly/dIdDn5a

The pursuit of 1.5°C endures as a legal and ethical imperative in a changing world As the world nears 1.5°C of global warming, near-term emissions reductions and adequate adaptation become ever more important to ensure a safe and livable planet for present and future generations

What becomes of the 1.5°C goal now that global warming is approaching that level?🌍🔥🌡️

In a new @science.org Policy Forum we explain how the 1.5°C goal remains a critical legal & ethical benchmark, even as the world nears and may soon exceed 1.5°C of global warming🧵1/
www.science.org/doi/10.1126/...

From litigation to misinformation, and COP30 to populism, our panel discussion was a lively affair.

Thank you to all of our panellists, everyone who attended the event, our co-hosts, the EU Delegation to the UK. #COP30 #CountdownToCOP30

Prof @joerirogelj.bsky.social warned that passing the 1.5°C goal only intensifies the legal & ethical obligations of the Paris Agreement.

Every fraction of warming creates a more dangerous world. Achieving net-negative emissions & bring warming back below 1.5°C must be the long-term goal.

In case you missed it...

The 🇪🇺 Scientific Advisory Board on Climate Change #ESABCC warns "against international carbon credits to meet the 2040 target, as they risk diverting resources from domestic investments and could undermine environmental integrity."

News item 👇 | Link to full report below

The paper, published in Science by @joerirogelj.bsky.social‬ & Lavanya Rajamani, argues that determining precisely when the world crosses 1.5°C is not necessary, because the decisions needed in response are already clear and do not suddenly change at that point.

Incisive and brilliant, an absolute must-read from Professors @joerirogelj.bsky.social & Lavanya Rajamani!

The pursuit of 1.5°C endures as a legal and ethical imperative in a changing world As the world nears 1.5°C of global warming, near-term emissions reductions and adequate adaptation become ever more important to ensure a safe and livable planet for present and future generations

For more insights and more details, read the full @science.org Policy Forum article: www.science.org/doi/10.1126/...
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🔍To conclude
The 1.5°C goal remains a critical organizing principle for climate governance.
Exceeding 1.5°C is not an endpoint but a signal for urgent, equitable, and legally grounded action to:
- Limit overshoot
- Reduce harm
- Restore ambition
12/

📑Legal salience increases with warming
Far from weakening the Paris Agreement, approaching or exceeding 1.5°C:
- Strengthens normative pressure
- Informs litigation and international legal interpretation
- Reaffirms the PA’s institutional relevance 11/

⚠️Loss & damage
Climate-related extreme weather already causes over 100-billion USD in attributable damages, and will increase strongly in a world beyond 1.5°C.
Current finance in the Fund for Responding to Loss and Damage remains several orders of magnitude below what is needed. 10/
www.frld.org

Emissions Gap Report 2024 As climate impacts intensify globally, the Emissions Gap Report 2024: No more hot air … please! finds that nations must deliver dramatically stronger ambition and action in the next round of Nationall...

👐Adaptation essential (2)
Current policy projections of the past decade have pointed towards global warming levels around 2°C by mid-century and 2.5-3°C by 2100.
Reaching 1.5°C of global warming would fundamentally not change much to this outlook. 9/
www.unep.org/resources/em...

👐Adaptation essential (1)
Adaptation should focus on managing climate risks equitably, focussing on global warming that cannot be categorically excluded rather than on global warming targets we aim to achieve. 9/

🌍 Equity and mitigation (2)
Many developing countries have not used their fair share of the 1.5°C-aligned carbon budget. Yet they now face intensified climate impacts and this reality raises a tension between emissions equity and rights-based climate action needs. 8/

Using net-zero carbon debt to track climate overshoot responsibility | PNAS Current emissions trends will likely deplete a 1.5 °C consistent carbon budget around the year 2030, resulting in at least a temporary exceedance, ...

🌍 Equity and mitigation (1)
Country responses include reducing emissions, supporting others, and planning for net-negative emissions.
The latter supports reversing global warming and reducing a country's net-zero carbon debt. 7/
www.pnas.org/doi/abs/10.1...

🔄 Continued relevance for mitigation
Even in an overshoot world, countries can pursue 1.5°C-aligned pathways, which are defined by equitable contributions from 2015 onward - the year in which the Paris Agreement was adopted. 6/

🌡️Overshoot matters
Every 0.1°C of warming increases the harm and damages vulnerable populations are exposed to.
Overshooting risks increase with both magnitude and duration by which 1.5°C is exceeded. Failure to minimize overshoot heightens states’ legal exposure for inadequate climate action. 5/

⚖️ Ongoing obligations
Crossing 1.5°C does not nullify states’ duties. Rather, it intensifies legal and moral responsibilities to act, grounded in:
1) Due diligence standards
2) The prevention of harm
3) Intergenerational equity 4/

🧾The Paris Agreement's 1.5°C goal
The 1.5°C goal within the Paris Agreement's temperature goal refers to pursuing efforts to limit warming to 1.5°C.

This pursuit can continue whether we are below, at, or above 1.5°C of global warming. 3/

🧾Legal status of the goal
The Paris Agreement’s temperature goal is not voided by temporary exceedance. It remains legally binding, directing ambition and accountability in mitigation, adaptation, and climate finance. 3/
unfccc.int/files/meetin...

📈For context
2024 was the warmest year on record with global temperatures exceeding 1.5°C above pre-industrial levels.
The underlying long-term warming trend (what the Paris Agreement refers to) is approaching 1.4°C and rising at ~0.27°C per decade.2/
agupubs.onlinelibrary.wiley.com/doi/10.1002/...

The pursuit of 1.5°C endures as a legal and ethical imperative in a changing world As the world nears 1.5°C of global warming, near-term emissions reductions and adequate adaptation become ever more important to ensure a safe and livable planet for present and future generations

What becomes of the 1.5°C goal now that global warming is approaching that level?🌍🔥🌡️

In a new @science.org Policy Forum we explain how the 1.5°C goal remains a critical legal & ethical benchmark, even as the world nears and may soon exceed 1.5°C of global warming🧵1/
www.science.org/doi/10.1126/...

Staple crops yields face ‘substantial losses’ in warming world – even with adaptation - Carbon Brief Average global yields of six staple crops could fall by more than 11% under a moderate warming scenario by the end of the century.

This is really important because it shows the limits of adaptation. We cannot adapt to everything - we cannot adapt our way out of climate change. Nice coverage of recent paper by Hultgren et al in @nature.com on impacts on agriculture considering adaptation.

www.carbonbrief.org/staple-crops...

Indicators of Global Climate Change 2024: annual update of key indicators of the state of the climate system and human influence Abstract. In a rapidly changing climate, evidence-based decision-making benefits from up-to-date and timely information. Here we compile monitoring datasets (published at https://doi.org/10.5281/zenod...

To explore the IGCC paper in more detail see here: essd.copernicus.org/articles/17/...
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Substantial reductions in non-CO2 greenhouse gas emissions reductions implied by IPCC estimates of the remaining carbon budget - Communications Earth & Environment Current best estimates of the remaining carbon budgets to meet the Paris Agreements goals assume substantial reductions in methane and other non-CO2 greenhouse gases, and failure to achieve these redu...

This makes for a remaining 1.5C carbon budget of 130 GtCO2. But note that depending on how successful or unsuccessful we are in limiting non-CO2 emissions, and particularly methane, this value can easily already be zero. For more information on this see this recent paper: doi.org/10.1038/s432... /7

IV) The last update takes into account the latest estimate of global warming. This estimate increased slightly due to the high observed temperatures in the last few years and resulted in a further reduction of the budget by around 40 GtCO2 relative to values reported in last year’s assessment. /6

III) Updates to the most recent set of scenarios that were compiled as part of IPCC Working Group 3 report meant a further very small reduction of 10 GtCO2. /5
zenodo.org/record/5886912