Peter Pfleiderer

How well can we quantify when 1.5 °C of global warming has been exceeded? Abstract. Parties to the 2015 Paris Agreement agreed to limit the long-term increase in global average temperature to well below 2 °C and pursue efforts to keep temperatures below 1.5 °C relative to p...

New discussion paper just dropped that’s taken shall we say a little work to get this far … essd.copernicus.org/preprints/es... please be kind. Not on an at all sensitive topic in the slightest.

D & A style attribution with fair and HadCRUT5 updated to 2025 (emissions extrapolated beyond 2022, but should make little difference)

[code: github.com/chrisroadmap...

Very nice, thanks for doing this! Can you quickly explain why the natural forcing is generally positive except a few dips?

This was a joint effort with:
Anna Merrifield, István Dunkl, Homer Durand, Enora Cariou, Julien Cattiaux, Gustau Camps-Valls, @sebastian-sippel.bsky.social

Decomposing a temperature signal into a "thermodynamic" and a "circulation-induced" part is a strong simplification and designing a benchmark dataset (-> nudged simulations) is not straight forward. A summary of our discussion on these challenges is in the paper. We are looking forward to your ideas

The decomposition methods adequately identify the spatial trend pattern. However, they all tend to underestimate the magnitude of the trend pattern. This shows that such evaluation efforts are crucial: By just comparing different methods we cannot identify biases that they all share.

We evaluate the statistical and machine learning decomposition methods against nudged circulation simulations: we apply the decomposition to a freely running simulation and compare it's estimated dynamical component to a simulation without GHG forcing but circulation nudged to the tested simulation

Emerging Climate Change Signals in Atmospheric Circulation Long term trends in atmospheric circulation are emerging across different regions and seasons with some attributed to human activities Many circulation signals have been linked to dynamical mecha...

We do not investigate to which extent this circulation induced warming is forced. Given that a changes in atmospheric circulation have been attributed to climate change, we assume that part of this signal is forced. More research is required to quantify the forced part. doi.org/10.1029/2024...

Over the period 1979-2023 circulation changes have contributed considerably to the warming of European summers. Over the mid-latitudes, a wavelike pattern is apparent with alternating regions of circulation induced warming and cooling.

Considerable yet contrasting regional imprint of circulation change on summer temperature trends across the Northern hemisphere mid-latitudes Abstract. Rising summer temperatures and more frequent heat extremes are well-documented outcomes of anthropogenic climate change. However, the extent to which atmospheric circulation changes contribu...

Summer temperatures have strongly been influenced by circulation changes in the northern mid-latitudes.

In our new study we evaluate and compare 4 statistical and ML methods that decompose trends into a "thermodynamical" and a "circulation induced" part.
wcd.copernicus.org/articles/7/8...

Graph that shows black dots for the annual average mean temperature (rising from 1970 to 2025) and the underlying contributions from GHGs in various shades of red.

5 Panels that schematically show the contribution to the global temperature change during the last 10 years. Red and blue colours indicate warming or cooling contributions

[...] We consider it more likely that the recent rate of global warming has been larger than anticipated, exceeding both the previous trend and what would be expected when considering only the observed pattern of greenhouse gas emissions.

berkeleyearth.org/global-tempe...

Multi-dataset comparison of global temperatures from 1850-2025, with 2025 values highlighted in a separate panel for each individual dataset. Baseline is a combination of 1850-1900 means.

Most 2025 global temperatures are now out (degrees C above 1850-1900 baseline)

1.41 HadCRUT5
1.44 Berkeley
1.46 JRA-3Q
1.47 Copernicus
1.53 DCENT-I

NOAA and NASA GISS values will be public at 2pm UK time and but based on already public Jan-Nov data they will likely be between 1.3 and 1.4 degC.

🌡️ 2025 was the third-warmest year on record, with a global average temperature 0.59°C above the 1991–2020 average & 1.47°C above the 1850–1900 pre-industrial level. It was 0.13°C below 2024, the warmest year on record, and only 0.01°C cooler than 2023.
@ecmwf.int

⬇️

🙀 Don't forget to submit your abstract for #EGU26

And please consider submitting to our nice session on Synoptic and Large-Scale Circulation Dynamics 😻

www.egu26.eu/session/56938

I'm to announce our session on Synoptic and Large-Scale Circulation Dynamics at #EGU26

www.egu26.eu/session/56938

... and I'm looking forward to read your abstracts together with
@mittermeierm.bsky.social
Jan Stryhal, Christoph Beck, Ileana Bladé

great enough :)

Nice graph! Is the colorscale stopping at 2? 0_o

Interesting update on SSTs and the state of warming:

I developed the model as part of my PhD at @climateanalytics.org together with @carlschleussner.bsky.social @marleneclimate.bsky.social and Tobias Geiger in 2020.
Since then, I'm doing the forecasts every year. Now from the climate causality and attribution group (lim-climate-causality.github.io)

Here is the model the description of the model: wcd.copernicus.org/articles/1/3...

2025 was again a severe #hurricane season with 4 major hurricanes (3 cat 5 hurricanes).
In terms of accumulated cyclone energy (ACE) it was slightly above a normal season.
Seasonal forecasts (including ours 🥳) predicted the ACE well this year 💪

The slightly above average ACE matches very well with seasonal forecasts 🥳

seasonalhurricanepredictions.bsc.es/forecast/sea...

I'm to announce our session on Synoptic and Large-Scale Circulation Dynamics at #EGU26

www.egu26.eu/session/56938

... and I'm looking forward to read your abstracts together with
@mittermeierm.bsky.social
Jan Stryhal, Christoph Beck, Ileana Bladé

.. and as a fundamental innovation also enabling us to investigate compound hazards.

Great work @shrutinath97.bsky.social @carlschleussner.bsky.social
@klimapeter.bsky.social J. Carreau & P. Naveau

@iiasa.ac.at @lamont.columbia.edu

MERCURY: A Fast and Versatile Multi‐Resolution Based Global Emulator of Compound Climate Hazards Climate model emulators traditionally generate global fields amounting to Peta-Bytes of data We introduce the emulator MERCURY, that employs a lifting scheme based on image compression techniques...

Climate emulators are a great tool to explore a wide range of possible climate futures. Here comes MERCURY - utilising the power of image-compression-based techniques for memory-efficient emulation. Fantastic work led by @shrutinath97.bsky.social agupubs.onlinelibrary.wiley.com/doi/10.1029/...

“Heat pumps are superior in efficiency to condensing boilers, even if the heat pumps are powered by electricity from a power station burning natural gas.”

Not me saying that but the late Prof Sir David MacKay.

More in my @carbonbrief.org article 👇

interactive.carbonbrief.org/factcheck/he...

METEORv1.0.1: a novel framework for emulating multi-timescale regional climate responses Abstract. Resolved spatial information for climate change projections is critical to any robust assessment of climate impacts and adaptation options. However, the range of spatially resolved future sc...

Want to get gridded temperature and precipitation responses to any future climate scenarios, including overshoot?
--> check out METEOR - a framework for emulating multi-timescale regional climate responses, with Marit Sandstad, Susanne Baur and @benmsanderson.bsky.social.

doi.org/10.5194/gmd-...

Hurricanes feed off of warm water. Watch how quickly the eye of #Melissa collapsed as it moved onto land and over the mountainous terrain of Jamaica, and how quickly it is reforming now that it has moved back over water! I will be adding this radar loop to my earth science lectures.

Screenshot that says "Melissa has passed over waters made 1.4°C warmer, on average, by climate change." and "Climate change made the ocean temperatures along Melissa's path 500 to 900 times more likely." along with a map of Hurricane Melissa's path.

To understand the climate connection to Hurricane Melissa, check out our real-time attribution page at @climatecentral.org: www.climatecentral.org/tropical-cyc...

"Climate change made the ocean temperatures along Melissa's path 500 to 900 times more likely."