In brief:

  • Scientists expect dramatic swings between active and inactive hurricane seasons in the future.
  • The risk of back-to-back hurricanes is growing. 
  • Hurricanes are expected to get more damaging and deadly. 

Wild year-to-year swings — from punishing hyperactive seasons to quiet years with little activity — could well become the norm for future Atlantic hurricane seasons, according to recent climate change research. 

The latest science paints a complex but alarming future, as the unprecedented amount of heat that humans are supplying to the climate system disrupts the fundamental atmospheric circulation pattern in which we designed our civilization. 

During the coming busy seasons, death and destruction from unprecedented hurricane catastrophes will probably grow much more commonplace, because even as risks grow, people have continued to build in risky flood-prone regions. But eventually, the coming hurricane catastrophes will pose an increasing threat to the viability of living in many coastal areas, particularly in the Caribbean.

Hurricane seasons will likely grow more erratic

The year-to-year variability of Atlantic basin hurricane activity already is the largest of any of the globe’s tropical cyclone basins. And climate change will make extreme swings between active and inactive hurricane seasons the norm, according to a 2024 paper, Projected increase in the frequency of extremely active Atlantic hurricane seasons. 

The high-resolution climate models used in the study projected a 36% increase by 2050 in the variance of Atlantic tropical cyclone activity. The main causes: an increase in the variability of wind shear (strong upper-level winds that tend to tear a storm apart), and major swings in how stable the atmosphere is in the tropical Atlantic. One good thing is that the study found that the increased activity during hyperactive seasons would be focused farther from land over the eastern and central Atlantic, with less activity over the Caribbean.

A 2022 study, Extreme Atlantic hurricane seasons made twice as likely by ocean warming, found that ocean warming from 1982 to 2020 doubled the probability of extremely active hurricane seasons over that time period. However, the authors did not clearly separate out how much of that change resulted from increased heat-trapping greenhouse gases and how much was caused by a reduction in planet-cooling air pollution particles called aerosols. These particles are not likely to change much in the future, while greenhouse gases will be increasing, so it is important to know their relative impacts on ocean warming.

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On the death of RCP8.5

Posted on 26 May 2026 by Zeke Hausfather

This is a re-post from The Climate Brink by Zeke Hausfather, Glen Peters, and Piers Forster

With the release of the new van Vuuren et al 2026 paper on the emissions scenarios that will be used in the upcoming IPCC 7th Assessment Report, the internet has been abuzz with debate over the implications of the formal retirement of the RCP8.5/SSP5-8.5 scenario. The president of the United States even weighed in over the weekend in his own unique style, posting that “the United Nations TOP Climate Committee just admitted that its own projections (RCP8.5) were WRONG! WRONG! WRONG!”.

van Vuuren et al justify this move by noting that “the CMIP6 high emission levels (quantified by SSP5-8.5) have become implausible, based on trends in the costs of renewables, the emergence of climate policy and recent emission trends,” citing the paper that we published in Nature back in 2020.

Actual global CO2 emissions (black) compared to different generations of emissions scenarios featured in IPCC reports. Updated by Glen Peters through 2025.

Others have pointed out that RCP8.5 was never particularly plausible, and have criticized claims that the move away from using these scenarios reflects actual progress on reducing emissions.

So what actually happened here? It turns out that two things can be true at the same time:

  • RCP8.5 (and its successor SSP5-8.5) were designed to be a worst case emissions scenario, not the most likely outcome even in a world that did nothing to address climate change. We were probably never headed to a tripling of global emissions by 2100 (to say nothing of a five-fold increase in coal use), even in the absence of climate policy.

  • Rapid declines in clean energy costs have bent the curve of future emissions downward, with new scenarios designed to reflect current policies notably lower than most baseline scenarios in the literature. The 21st century is now unlikely to see a continued expansion of fossil fuel use globally, with current policy scenarios reflecting relatively flat global emissions going forward.

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RCP8.5 Update

Posted on 25 May 2026 by Ken Rice

This is a re-post from And Then There's Physics

If you’ve been paying attention to the climate debate on social media you might have noticed the RCP8.5 debate rearing it’s ugly head again. This is because a new set of emission/concentration projections have been developed for the climate modelling community (CMIP7). These new projections no longer include an RCP8.5-like projection and so all of those who have been critical of its use are now crowing about this proving them right.

I’ve written about RCP8.5 numerous times before. My views have probably evolve somewhat over time, but my previous posts are probably a reasonably good reflection of them. So, if you do want to know them, you could read some of these earlier post. I don’t want to delve too much into the re-invigorated “debate” but instead thought I’d post links to other posts/articles that I think explain the situation pretty well. If you want to read alternative takes, they’re not all that difficult to find. You can probably guess the authors.

I will, though, repeat the sub-heading of Gavin’s Realclimate post:

The fantasy version of the normal updating of scenarios for a new round of CMIP simulations doing the rounds is bad faith BS.

Links to other posts:

Scenarios, Schemarios – Gavin Schmidt at Realclimate.
On the death of RCP8.5 – Zeke Hausfather, Glen Peters and Piers Foster at Climate Brink.
Factcheck: Trump’s false claims about the IPCC and ‘RCP8.5’ climate scenario – multiple authors at Carbon Brief.
IPCC does not create scenarios – Reto Knutti at Linkedin
Sorry, climate change is still dangerous, no matter what nonsense Trump emits – Bulletin article by Genevieve Guenther

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2026 SkS Weekly Climate Change & Global Warming News Roundup #21

Posted on 24 May 2026 by BaerbelW, Doug Bostrom

A listing of 28 news and opinion articles we found interesting and shared on social media during the past week: Sun, May 17, 2026 thru Sat, May 23, 2026.

Stories we promoted this week, by category:

Climate Policy and Politics (6 articles)

Climate Change Impacts (5 articles)

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Skeptical Science New Research for Week #21 2026

Posted on 21 May 2026 by Doug Bostrom, Marc Kodack

Open access notables

A desk piled high with research reports

Attribution of UK Temperature Changes to Anthropogenic and Natural Factors, Amos et al., Atmospheric Science Letters

Understanding the extent to which human activities have influenced regional climate is a key scientific and policy challenge. The UK is one of the world's best observed regions climatically, with a long and reliable temperature record that makes it an important test case for regional detection and attribution. Here, for the first time, we apply optimal fingerprinting to UK mean 2-m air temperature changes using the Estimating Equations method, HadUK-Grid observations, and CMIP6 simulations. We assess the extent to which observed UK temperature changes can be explained by natural internal variability, anthropogenic forcings, and natural external forcings. We detect a significant anthropogenic influence on warming in recent decades and identify greenhouse gases as the main driver. We also detect a cooling contribution from other anthropogenic influences in the mid-twentieth century, likely dominated by sulphate aerosols. These results update earlier UK-focused work and demonstrate that human influences, both warming and cooling, are detectable even at the national scale.

Sustained deoxygenation in global flowing waters under climate warming, Guan et al., Science Advances

Dissolved oxygen (DO), as a vital material sustaining aquatic ecosystems, has declined markedly in oceans, lakes, and coastal waters, yet unbiased understandings of changing DO concentrations in each individual river segment globally remain a challenge. Here, we estimate DO concentrations in 21,439 rivers globally between 1985 and 2023, based on Landsat observations and climatic data, and examine their patterns and trends. We find sustained deoxygenation in global rivers, at a rate of −0.045 mg liter−1 decade−1, with 78.8% experiencing fluvial deoxygenation, driven mainly by oxygen solubility and temperature. Moreover, short-term heatwaves and dam impoundment exert non-neglecting influence on these changes. Future projections demonstrate that global fluvial DO concentrations decline by 1.1% ± 1.6% under SSP1–2.6 and 4.7% ± 2.7% under SSP5–8.5 throughout the 21st century. Our study provides an unbiased baseline for escalating deoxygenation in global fluvial ecosystems that underscores targeted measures to mitigate deoxygenation threats and protect ecosystem health.

Emergent constraints on future methane emissions from global wetlands, Zhang et al., Nature Geoscience

Future methane (CH4) emissions from natural wetlands are predicted to increase due to global warming, leading to positive feedback on climate change. However, the magnitude of this increase remains highly uncertain. Here we present novel ensemble simulations of seven state-of-the-art terrestrial biosphere models to estimate wetland CH4 emissions (eCH4) during the twenty-first century. Our estimates suggest that for every 1 °C increase in global land surface temperature, there is a 24 ± 10 Tg CH4 yr−1 increase in eCH4. We also identify an emergent relationship between contemporary temperature dependence and projected eCH4. When constrained by 163 site-year eddy-covariance measurements of eCH4, we show that wetland emissions can increase by 50–60% by the 2090s relative to the 2010s under a high-warming scenario. The projected decadal increase in eCH4 from the 2010–2019 baseline to the 2030s would very likely (90% probability) offset an amount equivalent in scale to 8–10% of anthropogenic eCH4 at the 2020 level, comparable to the reductions committed under the Global Methane Pledge. However, the constraint is dominated by mid- and high-latitude observations, with limited tropical coverage, and uncertainties in projected wetland inundation contribute substantially to uncertainty in eCH4. Our findings reduce the uncertainty in projected wetland methane–climate feedback and highlight its potential impacts on methane mitigation efforts to slow global warming.

Challenges and opportunities of the full phase-out of fossil fuels under the 1.5 °C goal, Mori et al., Nature Communications

The COP28 decision called for transitioning away from fossil fuels, sparking a growing interest in their full phase-out. However, energy system transformation pathways towards a phase-out of fossil fuels, which may reduce the reliance on carbon dioxide removal to meet the 1.5 °C goal, remain unclear. Here, we employ two global energy system models to explore energy system transformations and the challenges and opportunities associated with attaining a full phase-out of fossil fuels. We found that phasing out fossil fuels by 2050 would require accelerating direct and indirect electrification, involving 1.6–1.8-fold increases in power generation compared to the conventional cost-effective 1.5 °C pathways. This transition from cost-effective to fossil fuel phase-out pathways would increase energy supply investments by up to 34% over this century and require accelerated deployment of solar and wind power, as well as electrolysers. Despite opportunities including lower reliance on carbon dioxide removal and increasing probability of returning to 1.5 °C after temperature overshoot, these additional requirements imply that international society must approach the transition towards zero-fossil energy systems with strong determination.

Scientific authority cues increase the spread of misinformation, Harrando et al., Proceedings of the National Academy of Sciences 

Misinformation continues to circulate on social media, often because people unintentionally share posts without verifying their accuracy. We show that references to scientific entities, what we call Scientific Authority Cues, play an important role in this problem. Analyzing 8.7 million posts on Twitter (X), we find that these cues are associated with an increase in sharing, especially when sharing low veracity content, and when users lean politically to the right. A preregistered experiment with U.S. adults shows that attributing claims to scientific entities increases people’s willingness to share them by making claims seem more accurate. These findings reveal an important tension: Signals of scientific authority can also make misinformation more credible and thus easier to spread.

From this week's government/NGO section:

The AI Climate Hoax: Behind the Curtain of How Big Tech Greenwashes Impacts, Ketan Joshi, Beyond Fossil Fuels, Standearth, Climate Action Against Disinformation et al

The analysis collected the most prominent AI climate claims and determined a) what types of AI were referred to and b) what evidence was presented to back up those claims. The author found that 1. Most claims of climate benefit relate to ‘traditional’ AI, which has a much lower environmental impact than consumer generative AI tools. Even if these benefits are real, they are unrelated to - and dwarfed by - the massive expansion of energy use from the generative AI industry. 2. Where claims of traditional AI climate benefits are made, they tend to rely on weaker forms of evidence, such as corporate websites, rather than published academic research. Only 26% cited published academic research while 36% did not cite any evidence at all. This analysis shows that to bring the deployment of digital services in bounds with the physical limits of the planet, tech companies investing in AI should implement actual sustainability measures rather than masking ever-worsening damage to the climate and environment with vague terms and weak evidence.

Survey: U.S. and Canadian Business Confidence in Climate Action Remains Strong, Melissa Fifield, BMO Climate Institute

The fourth edition of the BMO Climate Institute Business Leaders Survey was conducted in January 2026 and included 741 respondents, including 370 in Canada and 371 in the U.S. Survey respondents include individuals in a senior role at their company (e.g. C-suite, President, Vice-President, Executive Director or General Manager) and who consider themselves to be senior decision makers. Companies range from those with at least five employees to more than 500 employees. Nearly three-quarters (73%) of respondents say they have or are developing plans to address climate-related risks, up from 69% in 2025. Extreme and unpredictable weather is a top concern for business leaders considering the impact of climate-related risks on their companies. Competitive pressure, customer expectations, and regulatory change are expected to drive further climate action. Three?fifths of respondents say AI is already used in daily operations or climate planning. Costs remain the most frequently cited obstacle to developing an effective climate plan.

101 articles in 48 journals by 751 contributing authors

Physical science of climate change, effects

Future changes of upscale ocean kinetic energy transfer under greenhouse warming, Wang et al., npj Climate and Atmospheric Science Open Access pdf 10.1038/s41612-026-01429-1

Mean State Change-Induced Differential Responses Between Strong Positive and Negative Events Reduce Indian Ocean Dipole Asymmetry Under Greenhouse Warming, Wang et al., Journal of Geophysical Research Atmospheres 10.1029/2025jd045190

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