A provocative piece by @TedNordhaus in today's Wall Street Journal makes the case that effective climate policy is one that promotes human prosperity – particularly in poorer countries – while adopting policies to invest in and promote clean energy. wsj.com/articles/ignor… 1/7
The piece argues continuing political, economic and technological modernization, not a radical remaking of society, is key to both slowing climate change and adapting to it. It suggests a richer world is one of lower population growth, higher equality and adaptive capacity. 2/7
This is also the assumption underlying the future scenarios used by the IPCC. The most sustainable future (SSP1) with the easiest path to deep decarbonization is also one of the highest economic growth and lowest population scenarios considered: 3/7
Nordhaus argues "Long-term economic growth is associated with both rising per capita energy consumption and slower population growth. For this reason, as the world continues to get richer, higher per capita energy consumption is likely to be offset by a lower population." 4/7
Furthermore, a richer world is one where it is easier to decouple the growth of human welfare from environmental degradation, where "energy consumption should be less carbon-intensive than it would be in a poorer, less technologically advanced future." 5/7
There are strong linkages between growth and adaptive capacity: "In Bangladesh, 300,000 people died in Cyclone Bhola in 1970, when 80% of the population lived in extreme poverty. In 2019, with less than 20% in extreme poverty, Cyclone Fani killed just five people." 6/7
Of course, building human prosperity in a way that also reduces global emissions requires substantial policy interventions. The world has started bending the curve away from high emissions outcomes with investments in clean energy. This needs to have to expand dramatically: 7/7
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As a rare climate scientist working in Silicon Valley, I've been drinking from the AI firehose a lot more than my peers. I thought it would be helpful to lay out my experiences of both the promise and pitfalls of using AI to accelerate scientific research.
As a bit of background, I've been working with these tools since late 2022, and seen firsthand how they have dramatically improved over time. I’ve also worked with frontier AI labs to evaluate how well LLMs answer climate questions, and to help enable AI tools to support scientific collaboration.
So what do AI tools do well for scientific work? In short, coding.
Scientists are generally not software engineers. Much of their coding is self-taught, and many struggle with writing code quickly, producing well-documented reproducible code, and fixing errors.
My new State of the Climate report over at @CarbonBrief finds that 2025 had the:
⬆️ Warmest ocean heat content
⬆️ Tied as second warmest surface temps
⬆️ Second warmest troposphere
⬆️ Record high sea level and GHGs
⬇️ Record low winter Arctic ice
Read the article here:
Ocean heat content increased by 23 billion trillion joules, which was around 39 times greater than global primary energy use this year. This is the largest rise in OHC since 2017; overall OHC has increased by over 500 zettajoules since the 1940s.carbonbrief.org/state-of-the-c…
@CarbonBrief 2025 tied with 2023 as the second warmest surface temperatures. It was nominally the second warmest in NASA and DCENT datasets, and third warmest in NOAA, Hadley, Berkeley, Copernicus, JRA-3Q, and China-MST. In all cases uncertainties overlap with 2023.
After a modest decline over the first half of the year (and after record 2024 warmth), global temperatures are ticking back up. The past two days have been the warmest on record for this time of year in ERA5 and the highest temperature anomalies since January.
With 26 days of October now reporting in ERA5, October 2025 will be the third warmest on record after 2023 and 2024.
Weather models expect global temperatures to remain relatively flat over the coming week as extreme Northern Hemisphere warmth persists, and anomalies (departures from normal) will be at or above the levels the highest levels any we've seen earlier in the year
Last week the German Meteorological Society warned that "the 3-degree limit could be exceeded as early as 2050".
While not possible to fully rule out, the assessed warming scenarios we published in the IPCC AR6 report find this to be extremely unlikely.
If we look a the full ensemble of CMIP6 models we see a small number (3 of 37 models) reaching 3C by 2050. However, these three have both too much historical warming (~2.2C in 2024) and what an unrealistically high climate sensitivity (>5C per doubling CO2) as we noted here: nature.com/articles/d4158…
However, if we constrain CMIP6 to match recent observed global temperatures, we see no models reaching 3C until at least 2060: carbonbrief.org/analysis-what-…
The EPA cited my paper in their argument against the endangerment finding today. However, their point is completely backwards: my paper actually supports the EPA's 2009 range of 1.8C to 4C warming by 2100. nature.com/articles/d4158…
Specifically, in our paper we argue that RCP4.5 or RCP6.0 are more realistic representations of 2100 warming under current policy than the increasingly implausible RCP8.5 scenario. But the lower of those two – RCP4.5 – gives a 2100 warming range of 1.8C to 4C!
Its only the high end warming outcomes of >4C that have become increasingly unlikely as the world has moved toward lower emissions scenarios. The wide range of climate sensitivity and carbon cycle feedbacks still makes it impossible to rule out up to 4C: journals.sagepub.com/doi/10.1177/29…
I just published an explainer on aerosols and their role in the climate that I've been working on for the past few months! It includes both how aerosols work, how emissions have changed, and how thats driven recent warming (link below).
Human-caused emissions of aerosols – tiny, light‑scattering particles produced mainly by burning fossil fuels – have long acted as an invisible brake on global warming. This is largely because they absorb or reflect incoming sunlight and influence the formation and brightness of clouds.
Aerosols also have a substantial impact on human health, with poor outdoor air quality from particulate matter contributing to millions of premature deaths. Efforts to improve air quality around the world in recent decades have reduced aerosol emissions, bringing widespread benefits for health.