2021 is off to a cooler start, with the seventh warmest Jan-April period since records began in the mid-1800s.
That said, it is still warmer than 164 of the 171 years on record, showing just how much human activity has changed what seems normal. carbonbrief.org/state-of-the-c…
Based on the first four months temperatures and the El Nino/La Nina forecast, @CarbonBrief estimates that annual 2021 temperatures also gave the best chance of ending up as the 7th warmest year on record – and its very likely to be somewhere between the fourth and ninth warmest.
We do not expect every year to set a new record in a warming world, as a lot of year-to-year variability is influenced by El Nino and La Nina cycles. The moderate La Nina event in late 2020 and early 2021 is contributing to cooler temperatures, though its is quickly fading:
Observations are still running pretty close to the average projected by all the climate models (CMIP5) included in the last IPCC report:
Sea ice is on the low end of the historical range (1979-2010) in the Arctic, and is close to normal in the Antarctic so far this year:
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With all the July model runs now in, it is very likely that 2026 will see the largest El Niño event since records began in the late 1800s – and potentially by a truly mind-blowing margin. The median estimate is now 3.6C, roughly 0.8C hotter than the prior record (2.75C).
The 2026/2027 El Niño event has already grown faster than any prior events (at least on an ONI basis). Here its observed and projected future evolution compared to the strongest prior El Niño events in recorded history.
Currently 13 out of 14 dynamical models expect a record setting event based on the Niño 3.4 region sea surface temperature anomalies (ONI), with overall odds of a record sitting at 91% across all 667 model ensemble members.
Heat waves are driven by weather patterns but occur on the backdrop of a rapidly warming world. Without climate change the current European heat wave would have been ~3.2 °C (5.8 °F) cooler.
Heat impacts are non-linear, so this higher severity can lead to much greater suffering
Europe has been warming at a much faster rate than the world as a whole: roughly twice as fast as the global average, and 40% faster than the global land average.
This warming has been fastest in the winter months – driven in part by greater absorption of sunlight with less winter snow cover – but has been rapid year-round:
Today the @WMO released projections of where temperatures may end up over the next five years (baed on 13 different models and 250 ensemble members).
Their estimates for 2026 and 2027 are quite close to my (updated) ones:
My 2026 uncertainties are narrower as I'm using the first four months of data for the year to constrain my estimate. I also have a more up-to-date El Nino forecast than the WMO models (which are initialized considerably earlier and don't reflect the likely development of a very strong event.
@WMO I've also updated my estimates using data through April and the latest El Nino forecasts, which slightly bumped up the 2026 and 2027 central values compared to my last estimate that only used data through March: theclimatebrink.com/p/higher-warmi…
The arc of the scenario universe is long, but it bends inevitably toward more realistic emissions.
A new paper outlining the emissions scenarios we will be using in the upcoming IPCC AR7 report notes that "the CMIP6 high emission levels (quantified by SSP5-8.5) have become implausible".
It outlines a yet-to-be-released high emissions scenario notably lower than the one (SSP5-8.5) used in the prior IPCC 6th Assessment Report:
This is a change that a number of us in the community have long advocated, going back to Justin Ritchie's work in 2017.gmd.copernicus.org/articles/19/26…
And in 2020 Glen Peters and I published a piece in Nature arguing that high emissions scenarios were no longer "business as usual", and that more realistic emissions make for better climate policy: nature.com/articles/d4158…
El Niño is coming, and it is shaping up to be a big one.
Over at The Climate Brink I've put together a compilation of the latest forecasts by different modeling groups. They suggest that we might see an event comparable in strength to what we saw in 2016.
This is based on a collection of 11 different models (and 455 individual ensemble members) all updated since the start of March. I've put an interactive version of the data up on the Climate Dashboard here: dashboard.theclimatebrink.com/#enso
While there remains a big spread in models (and some models only run through August), more than half the runs show a strong (>1.5C Nino3.4) event developing by August and a very strong event (>2C) by the end of the year.
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.