I thoroughly believe in celebrating the small victories, so here is a tiny one.

The percentage of humanity's energy system that is derived from fossil fuels, ticked down again in 2024 and is now technically at the lowest level since the 1960s, though fossil fuels still dominate. This change is more noticeable if one focuses on just electricity (rather than all forms of energy), as the rise of solar and wind electricity have been grabbing market share at a rapid pace.

The Northern Pacific Ocean is currently smashing temperature records.

And it is reaching these levels far earlier than the current generation of climate models had expected.

A short thread 🧵 Nearly the entire Northern Pacific is experiencing a strong marine heat wave, with record warmth in Japan and abnormally warm waters stretching all the way to the North American coastline.

This much extra warmth in a large ocean basin is very rare.



2/ berkeleyearth.org/august-2025-te…

In case anyone is wondering, about 1/2 of the 150 million tonnes of water vapor injected into the stratosphere by the extremely violent Hunga Tonga eruption (January 2022) is still there.

A fascinating natural experiment for upper atmospheric chemistry and dynamics.

🧵 After the initial plume settled at ~25 km altitude, the water vapor has mostly migrated to higher levels.

Ordinarily, the tropopause (~12-15 km high) greatly limits water vapor from reaching the stratosphere, so the stratosphere is very dry (only a few ppm of water).

2/

A new paper led by Sebastian Sippel just appeared in Nature arguing that ocean temperature measurements in the early 20th century have a cold bias.

It's a fun story illustrating the process of scientific discovery, so let me talk about it a bit. 🧵

nature.com/articles/s4158… Before I begin, I should note that I am one of the 11 coauthors on this new paper. My contributions are actually fairly modest, and Sebastian and others deserve the lion's share of the credit for developing this work over more than 2 years.

2/

So, what does the re-election of Donald Trump mean for climate change?

We can make some educated guesses based on his first term, his campaign, and the expressed wishes of his allies.

A few of my thoughts as a thread. 🧵 Firstly, a Trump administration obviously means abandoning any leadership role in the global fight against climate change.

He has promised to re-withdraw from the Paris Agreement on Climate Change, and possibly the UNFCCC as well.

2/

Heatwaves, wildfires, floods, storms...

Extreme weather gets the headlines.

For a few, climate change will arrive with life-altering violence. But for many, the early consequences of climate change will be more subtle and pernicious.

In a word: Inflation.

Let me explain... As weather patterns change, a few will suffer greatly, but many will share some of the financial costs incurred.

Lost crops -> Higher food costs
Damaged homes -> Higher home insurance costs
Damaged infrastructure -> Higher taxes

Etc.

How warm was 2023?

It was the first year that any of the major temperature analysis groups exceeded 1.5 °C above their "preindustrial" 1850-1900 average, thus touching the Paris Agreement limit. Under the Paris Agreement on Climate Change countries agreed to "pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels".

The exact definition of how that would be measured is intentionally vaguely, but most agree it refers to a multi-year average.

The Hunga Tonga–Hunga Haʻapai eruption was unusually water rich (& sulfur poor), injecting ~150 million tonnes of water into the stratosphere, increasing global upper atmosphere water mass by ~15%.

As a powerful greenhouse gas, this water may have contributed to recent warming. Water is much more abundant in the lower atmosphere but has difficulty crossing the tropopause (12-20 km) due to the very low temperatures.

The Hunga Tonga–Hunga Haʻapai eruption burst through in early 2022 and has since spread through the upper atmosphere.

Three years ago, new international rules took effect limiting sulfur in the heavy fuels used by ships.

Practically overnight, maritime sulfur pollution dropped 85%. This is good for humans, as sulfur pollution is toxic, but probably had unintended climate consequences.

A 🧵 Traditionally, ships often use heavy fuel oils that are the residues of petroleum refining too toxic to be allowed on land. For example, this often included a high level of sulfur.

Unfortunately, sulfur-rich fuels caused air pollution that was literally killing people.

2/

New Spanish national temperature record for April.

A scorching and unseasonable blast of hot air from North Africa has pushed Córdoba airport to 38.8 °C (101.8 °F), almost 5 °C (9 °F) warmer than the previous April record at this location. Others have said that this measurement is also a new European record for the month of April.

That seems plausible to me, but I haven't had a chance to verify it myself yet.

How has Twitter changed for climate scientists since Elon Muck bought it?

Fewer active scientists, fewer tweets, fewer likes per tweet, fewer retweets per tweet, and less likely to go viral.

A thread with some data. 🧵 Twitter has long been a fun side activity for many climate scientists, with the hopes of sharing some knowledge with the public and connecting with other scientists.

@KHayhoe has prepared a list of almost 3,200 scientists who work on climate issues:

twitter.com/i/lists/105306…

2/

Story of police killing a little girl's goat is really sticking with me.

As such, I read the actual lawsuit. If anything, some of the details therein make it even worse.

If there is any justice, their needs to be a large punitive judgment in this case.

Details follow. 🧵

https://twitter.com/JMShumway/status/1642012724979986432

Amended legal complaint: reason.com/wp-content/upl…

Background: With her mother, a 9-year-old girl participating in 4-H bought a baby goat called Cedar.

She raised this goat for 3 months & bonded with it.

The original plan was for the goat to be sold for meat.

Congratulations to all the scientists and others who have completed the AR6 Synthesis Report: ipcc.ch/report/ar6/syr/

This is the final report of the 6th @IPCC_CH assessment cycle.

A few highlights in following tweets. @IPCC_CH In the world's worst choose-your-own-adventure, we have already warmed ~1.2 °C (~2.2 °F).

Now our actions will determine whether today's children will see a world warmed by 1.5 °C, 2 °C, 3 °C or more.

Existing policies and practices would carry us to 3.2 °C (5.8 °F) by 2100.

Bit of a technical post, but here is a chart showing the sources of uncertainty in one of the modern estimates of global climate change since 1850.

For most of the last 170 years, ocean temperature uncertainties are actually more impactful that land uncertainties. When we talk about temperature uncertainties, we are talking about the little error bars added to charts like this, based on a scientific assessment of the "known unknowns".

The assessed uncertainties are much smaller than the long-term trend.

Let's talk a little about high altitude balloon flights.

When it comes to small balloons, such flights are surprisingly poorly regulated, and as a result there is often no quick way to distinguish benign balloons from potentially hostile ones. The Chinese flew an enormous balloon, described as 40-60 m (130-200 ft).

However, many high-altitude balloons are much, much smaller. The one shot down over Alaska was described as about the size of "a small car".

Later this month, "The Climate Book" edited by @GretaThunberg will arrive on bookshelves.

I don't usually talk about individual products, but this is one that I think a lot of you will enjoy.

How do I know? I was one of the experts asked to help check it for accuracy.

A 🧵 First, a quick caveat.

What I got to look at was an intermediate draft of the book. I haven't seen the final version, so some things might have changed.

2/

Every year a new layer of snow falls on Greenland & Antarctica. As the snow compacts into ice, tiny bubbles of air get trapped.

By carefully sampling the bubbles in old layers of ice, we can measure the past atmosphere.

That's how we know carbon dioxide has increased 50%. Why has carbon dioxide increased 50%?

Humans did it. By burning fossil fuels (and to a lesser extent clearing land), we have disrupted the carbon cycle.

We have dumped more than 450 billion tonnes of carbon into the atmosphere.

https://twitter.com/RARohde/status/1131224330241806337

West Virginia v. EPA is potentially the most consequential US Supreme Court case remaining to be decided.

The immediate issue is the limits of the EPA's ability to regulate greenhouse gases.

The broader issue is the ability of Federal agencies to regulate anything at all.

1/ A narrow ruling (e.g. on jurisdictional grounds) or a win for the EPA, would more or less leave things as they are.

However, a broad ruling could prevent the EPA from regulating greenhouse gases, and impose new limits on the ability of all agencies to issue regulations.

2/

A bit of chaos in the morning.

20,000 double pendula with very slightly different initial positions.

Simple physics cause the initial distribution to get stretched and then repeatedly folded until it is all mixed up.

Circle size indicates proximity to initial neighbors. This animation was inspired by a similar one by @moebio, though he chose to emphasize slightly different features in the way he rendered his version.

https://twitter.com/moebio/status/1533840079994634243

Unfortunately, abortion access remains a divisive issue in America.

49% of Americans identify as pro-choice.

70% of Democrats identify as pro-choice, as do 53% of Independents, and 22% of Republicans.

news.gallup.com/poll/1576/abor…

news.gallup.com/poll/246278/ab… 45% say abortion should be legal is "all" or "most" circumstances. 33% say is should be legal in a "few" circumstances, and 18% say it should be illegal is "all" circumstances.

60% of Americans say abortion should be "generally legal" during the first trimester.

This is a good example of how accurate, factual information can sometimes mislead people who lack the right framework for understanding it.

There is a serious heatwave in India & Pakistan, but the depicted land surface temperatures can be 10°C (18°F) or more hotter than the air.

https://twitter.com/NickGBreeze/status/1520492351726174208

The land surface temperatures, as seen by satellites, are different from the air temperatures.

Just as asphalt or sand can get very hot in the sun, so can the land.

Traditional weather reports measure air temperature in the shade and have been 40-50 °C (105-120 °F).