Extreme Temperature Diary- Tuesday October 7th, 2025/Main Topic: The Ocean Is a Carbon Toilet. Marine Heat Waves Are Clogging It. – Guy On Climate
Dear Diary. I’ve stated the obvious on many a post that the oceans hold the bulk of stored heat in our biosphere, much more than just the atmosphere alone. They also are our greatest carbon sync, significantly more than all the world’s forests. Unfortunately, the oceans will not be able to intact much more carbon soon because of an interruption in the growth of zooplankton, which is our main topic of today.
We can see one of the end results of this interruption in a north Pacific marine heatwave noted by some experts here:
Here is much more from Grist:
Up. Up. And away!
North Pacific water temps the past 15 years, with September 2025 being the cherry on the top (right) of the chart. @zacklabe.com is going to need a bigger Y axis! — Jeff Berardelli (@weatherprof.bsky.social) 2025-10-07T02:23:41.392Z
The ocean is a carbon toilet. Marine heat waves are clogging it. | Grist
The ocean is a carbon toilet. Marine heat waves are clogging it.Tiny poops are supposed to sink to the seafloor, locking away carbon. But scientists have found that warm spells are disrupting that flushing. Kevin Carter/Getty Images
Matt Simon Senior Staff Writer
Published Oct 06, 2025
Topic Climate
The planet would be a whole lot hotter if it weren’t for fecal pellets. Across the world’s oceans, tiny organisms known as phytoplankton harvest the sun’s energy, gobbling up carbon dioxide and releasing oxygen. They’re eaten by little animals called zooplankton, which poop out pellets that sink to the seafloor. What is essentially a giant toilet, then, flushes carbon at the surface into the depths, where it stays locked away from the atmosphere, thus keeping the amount of CO2 up there in check.
But as humans pump ever more carbon into the sky, relentlessly raising ocean temperatures, worrying signals are flashing that this commode could be changing in profound ways. Consider the northeastern Pacific, off the coast of Alaska, where two major heat waves took hold of the sea, one from 2013 to 2015 and the other from 2019 to 2020. A new study found the two events transformed the composition of phytoplankton and zooplankton, essentially clogging the toilet and preventing the downward transport of carbon into the depths.
“These long-term studies help put everything into context and also really sound the alarms,” said Anya Štajner, a PhD candidate in biological oceanography at the Scripps Institution of Oceanography, who wasn’t involved in the research. “The ocean is changing. And not only is it going to affect the ocean — it’s going to affect the life in the ocean. And eventually that’s going to affect us, because we rely on the ocean for our air, our food, our climate regulation.”
Of course, each bit of the world’s oceans has its own unique chemistry, biology, and ecology, so what happens there might not happen everywhere. But with these bursts of heat, this swath of the sea saw declines in its ability to sequester the gas that’s heating the planet. That’s a precarious situation, given that the oceans capture a quarter of humanity’s CO2 emissions. “While we can generalize that maybe what we saw here would happen in general across other marine heat waves in the ocean, like the carbon accumulation, I think it’s important to assess that regionally as well,” said Colleen Kellogg, a microbial oceanographer at Canada’s Hakai Institute and co-author of the paper, which published today in the journal Nature Communications.
The researchers tapped a decade of data from Biogeochemical Argo floats, which autonomously wander up and down the water column taking readings of ocean chemistry. When they reach the surface, they ping that data to a satellite. In this way, the scientists got a 10-year stream of readings without having to constantly be on a boat in the northeastern subarctic Pacific Ocean, which is not known for hospitable winters.
 A robotic float, which moves up and down the water column collecting data © 2022 MBARI
The two ocean heat waves started like those we experience on land, with the atmosphere warming things up. Indeed, the ocean has absorbed 90 percent of the additional heat that humans have created. Accordingly, while in the 19th century just 2 percent of the ocean surface experienced bouts of extreme temperatures, that figure is now well over 50 percent. Such events will only grow more common and more intense unless humanity dramatically reduces its greenhouse gas emissions, and fast. As it happens, the northern Pacific has once again been smashing records of late, perhaps in part due to regulations in 2020 cutting the amount of aerosols generated by ships, which usually cool the planet by reflecting the sun’s energy back into space.
Like our most ferocious atmospheric blasts of heat, a lack of wind during the two events made matters even worse. Typically, after the seawater warms in the spring and summer, winter winds blow across the surface, pushing it along. This forces deeper, cooler waters to race upward to fill the void, keeping the water column more uniform, temperature-wise. This didn’t happen during both heat waves, and the sea remained more stagnant, as it normally does later in the year.
Because warmer water is less dense, it remains at the surface, creating a sort of cap. “Then in the subsequent spring and summer, that water is even warmer, because it didn’t cool the winter before,” said Mariana Bif, a marine biogeochemist at the University of Miami and lead author of the paper. (Bif conducted the research while at the Monterey Bay Aquarium Research Institute.) “So the impact of marine heat waves starts in the atmosphere, and then it’s transferred into the ocean.”
The two heating events were not created equal, though. The first coincided with an El Niño — a band of warm water off the coast of South America — that raised temperatures in the northeast Pacific even higher. The second saw a marked decrease in salinity due to changes in ocean circulation. Because water with lower salinity is less dense, it hangs around the surface, as the saltier stuff sinks. This further strengthened the warm cap.
The lack of winter churning also meant the nutrients typically drawn from deeper waters were cut off, denying the phytoplankton in that cap of the elements they needed to grow. Together, the high heat and low nutrients at the surface totally changed the environment for the organisms living and processing carbon there.
Read Next
 The oceans just hit an ominous milestone
Matt Simon
That transformed the ecosystem. Like plants on land, different types of phytoplankton need different amounts of nutrients, and in different proportions. “Usually, for example, in areas where you have this great mixing and great nutrients, you have a bunch of large phytoplankton that produce a lot of carbon — a lot of biomass,” Bif said.
As conditions changed during the heat waves, it was the littlest of phytoplankton species that benefited. These needed less nutrients to bloom, so they proliferated as larger species declined. And because different species of zooplankton dine on differently sized phytoplankton, the smaller ones that ate the smaller species suddenly had much more sustenance. “Those guys are going to make smaller fecal pellets, which would kind of float in the water more than sink,” Kellogg said. “So that could be contributing to the reduction in carbon moving from the surface to the deep ocean.”
Because the researchers had access to that data up and down the water column, they could monitor how all that carbon was sinking during the heat waves. Or rather, how it wasn’t — because the ocean’s carbon toilet was malfunctioning. In the first event, carbon particles were piling up 660 feet deep, and in the second, between 660 and 1,320 feet. In these zones, zooplankton grazers continued to chew on the particles, breaking them into smaller bits that couldn’t sink. In the second marine heatwave, an increase in particularly small zooplankton meant more production of tinier, non-sinking fecal pellets.
Not only was the toilet not properly flushing carbon, but more and more waste was being added to these waters as the heat waves rolled on. This gave bacteria lots of organic matter to break down, adding CO2 back into the sea. Eventually, currents would bring that CO2-rich water back to the surface, where the gas can be released back into the atmosphere.
Now scientists will have to monitor more heat waves in other parts of the world’s oceans to see if the same dynamics are at play, and how much that might be hobbling the sea’s ability to sequester carbon. At the same time, phytoplankton and zooplankton are suffering through crises other than heat, like ocean acidification potentially interfering with some species’ ability to grow protective shells.
If there’s less phytoplankton, there will be less oxygen coming out of the oceans, and less food for the zooplankton that feed all manner of other animals in the sea, including whales. “Paying attention to what’s happening at the base of the food web is going to give us a lot of information,” Štajner said, “both about how things are going to trickle up to these larger marine animals that we care about, but also insights about our climate.”
Luckily, with thousands of Biogeochemical Argo floats collecting data around the planet, researchers are getting an ever-clearer picture of how seas are changing, and phytoplankton along with them. “The oceans are very under-sampled, very understudied,” Bif said. “But they play a central role in climate. We can’t understand what we can’t observe.”
Here are more “ETs” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as any extreme precipitation reports:
Very mild air reached the Arctics:
After yesterday's record warm in Scotland with 22.0C at 22.0 Fyvie Castle (Oct record tied),
today October historical records fell in the Svalbard:
10.9 Isfjord Radio
10.6 Akseloya
10.2 Svalbard Lufthavn
9.0 Hornsund
+15C also in Greenland — Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-10-07T17:46:03.457Z
EXTRAORDINARY HEAT ALLOVER ASIA
There has never been anything like this,
records smashed everywhere
MALDIVES Records in ALL ATOLLS
33.2 Kadhdhoo
33.1 Gan
MINS
28.6 Male HOTTEST OCTOBER NIGHT IN MALDIVES
28.4 Kadhodhoo
THAILAND
35.9 Nong Phlub
S.KOREA Still summer
31.3 Sogwipo — Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-10-07T15:12:41.828Z
EAST ASIA HISTORIC HEAT
MINIMUMS
25.2 Jeju,25.1 Sogwipo
HOTTEST OCTOBER NIGHT IN KOREAS
Record High max:30.5 Wando
In CHINA Absolute madness
October Record High Minimums:
27.0 Shanghai
27.8 Hangzhou
28.9 Jinhua
28.5 Nanchang
27.2 Fuzhou
Shaoxing, Jiaxing,Ningde... — Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-10-07T11:44:28.249Z
China's heat wave continued today, with Hengnan and Changshan reaching 39C; 7 stations broke&tied the October highest temperature record, and 65 stations broke&tied the highest night temperature record (the highest record for daily minimum temperature)! — Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-10-07T13:00:14.337Z
EXTRAORDINARY HEAT IN JAPAN
Suffocating heat 24/7 goes on.
October records:
33.4 Ishigaki
33.4 Hateruma
33.1 Ue
33.0 Kanoya
32.9 KItahara
32.7 Koniya
32.6 Ozu
29.6 Takamori
High minimums
28.3 Naha and Ashimine
28.1 Naze and Okinoerabu
27.8 Amagi
Summer will continue for weeks! — Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-10-07T09:09:07.110Z
More October heat records were shattered today in Eastern Canada; some of them by more than 3°C! Several locations exceeded 30°C once again.
Two provincial October records were also set/tied in NB and PEI. — Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-10-07T00:03:02.790Z
Record also in the Prince Edward Island
HUNDREDS of records smashed between NE USA (next posts) ,Ontario,Quebec,New Brunwick,Nova Scotia,Prince Edward Island and Newfoundland and Labrador.
‼️North America is living one of the top most extreme events in all climatic history
>2000 records in 6 days. — Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-10-06T21:35:41.183Z
UNBELIEVABLE HEAT IN CANADA🇨🇦
Tropical nights in Quebec !
TMins 20.3 La Pocatiere,20 Ile Madaleine
TMAX
31.1 KOUCHIBOUGUAC
OCTOBER HOTTEST DAY EVER IN NEW BRUNSWICK
30.9 Bathurst,30.7 Frederictonetc
12 stations >30C in NB and NS
HUNDREDS OF RECORDS BRUTALIZED
(See Mins/Maxes)👇 — Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-10-06T21:15:28.480Z
OCTOBER SUMMER goes on
Dozens of October records include
MAINE
87 Fryeberg
86 Augusta
84 Houlton and Presque Isle
83 Caribou
VERMONT yesterday
86 Burlington
86 Highgate and Morrisville
85 Springfield
NY
88 Dansville
Min 67 Montauk
MICHIGAN
Min 68 Muskegon
More records tomorrow! — Extreme Temperatures Around the World (@extremetemps.bsky.social) 2025-10-06T23:01:33.385Z
At least 170 US hospitals face major flood risk. Experts say Trump is making it worse.
At many of these facilities, flooding from heavy storms has the potential to jeopardize patient care, block access to emergency rooms, and force evacuations.
grist.org/accountabili...
#Health #Hospitals #Floods — Grist (@grist.org) 2025-10-06T15:09:07.564Z
Yale researchers didn't stop there. They also identified what people most need to know to catalyze action and support climate policy; and it's not about global temps, ice sheets, or ocean currents.
What people most need to know about climate change is that (1) others care, and (2) there is hope. — Katharine Hayhoe (@katharinehayhoe.com) 2025-10-06T15:28:49.880Z
Read a short climate fiction story today!
You Only Love Rivers That Kill You.
Two young men navigate grief and rivers in a Kansas City that is showing signs of healing from climate change, toxic contamination, and racism.
grist.org/climate-fict...
#ClimateFiction #Solarpunk #Fiction #BookSky — Grist (@grist.org) 2025-10-06T15:10:33.562Z
An absurdist theater artist prepares New Yorkers for climate disasters.
"Sometimes a one-page pamphlet translated into two languages isn’t the best way for people to receive information, but a song about go-bags played on the synth is."
grist.org/culture/an-a...
#Theater #Climate #Art #Artists — Grist (@grist.org) 2025-10-06T17:39:53.853Z
The ambitious plan to protect Northern California’s Plumas National Forest from wildfires.
To shield the forest and its communities from the next megafire, the Forest Service plans to burn it — intentionally.
grist.org/wildfires/th...
#CA #California #Wildfire #Disaster #Environment — Grist (@grist.org) 2025-10-07T13:14:02.196Z
Important #climate win.
Surprise ruling from *this* SCOTUS. — Rhuta Bhayga (@rhutabhayga.bsky.social) 2025-10-07T14:36:34.058Z
Who's ready to elect @debhaalandnm.bsky.social as Governor of #NewMexico? 🎉🎉 Here at JanePAC, we're so excited to endorse her campaign — and when you look at Deb's #Climate record, it's not hard to see why. 🧵1/4 — Jane Fonda Climate PAC (JanePAC) (@janeclimatepac.bsky.social) 2025-10-06T18:00:09.921Z
Climate action isn’t stopping. The 2025 Grist50 spotlights 50 people reshaping arts, tech, food, land, policy and science. 10 years, 500 change-makers. Progress is alive — meet the leaders moving us forward.
Read more here: grist.org/fix/grist-50...
#Climate #Leadership #Arts #Tech #Business #Land — Grist (@grist.org) 2025-10-06T16:51:52.742Z
The northern Leeward Islands will need to watch out for newly-formed Tropical Storm Jerry. yaleclimateconnections.org/2025/10/trop... — Dr. Jeff Masters (@drjeffmasters.bsky.social) 2025-10-07T15:48:12.500Z
T.S.#Jerry forms. Forecast to become a #hurricane. No threat to the US. — Jeff Berardelli (@weatherprof.bsky.social) 2025-10-07T14:53:19.218Z
A guide to the 4 minerals shaping the world’s energy future.
To address climate change, we're going to need a whole lot of metal.
grist.org/energy/criti...
#Mining #Mines #Climate #Lithium #CleanEnergy #Renewables #EV #Cars — Grist (@grist.org) 2025-10-07T16:04:18.265Z
BBC: Renewables overtake coal as world's biggest source of electricity
https://www.bbc.com/news/articles/cx2rz08en2po
#climateemergency #climate — AI6YR Ben (@ai6yr.m.ai6yr.org.ap.brid.gy) 2025-10-07T05:05:24.000Z
Who really controls your power bill? ⚡
Charles Hua is pulling back the curtain on the 200 regulators who shape U.S. energy policy.
grist.org/fix/grist-50...
#Energy #Climate #CleanEnergy #Renewables #GreenSky — Grist (@grist.org) 2025-10-07T18:35:49.731Z
This week, we lost one of the world’s greatest advocates for people and nature. Even in her final days, Dr. Jane Goodall was urging us not to give up, and now her legacy lives on through the countless voices she inspired.
Read on Mailchimp: shorturl.at/lDxXk
Read on LinkedIn: shorturl.at/VOiPa — Katharine Hayhoe (@katharinehayhoe.com) 2025-10-06T23:10:15.097Z
Small farmers are more squeezed than ever. A California grant program offers a lifeline.
grist.org/food-and-agr...
#Farms #Food #CA #California #Agriculture — Grist (@grist.org) 2025-10-07T19:16:41.578Z
This designer is helping Puerto Rico rebuild — by putting power back in residents’ hands.
Through her nonprofit La Maraña, Cynthia Burgos López works with communities to design and rebuild climate-resilient spaces that reflect their needs and voices.
grist.org/fix/grist-50...
#PuertoRico #PR — Grist (@grist.org) 2025-10-07T18:33:16.850Z
After a Grist investigation revealing exposure to the carcinogen ethylene oxide, El Paso residents confront troubling questions about their health.
grist.org/accountabili...
#Cancer #Health #TX #Texas #ElPaso #Toxic — Grist (@grist.org) 2025-10-07T13:15:40.091Z
5 things to know about the fungal infection valley fever.
Learn how the disease spreads, how to recognize common symptoms, and how it's diagnosed and treated.
grist.org/health/5-thi...
#Disease #AZ #Arizona #Climate #Environment #Health #PublicHealth — Grist (@grist.org) 2025-10-07T13:20:18.622Z
Breast cancer, dizziness, headaches: El Paso residents ask if a warehouse’s toxic emissions are to blame.
grist.org/accountabili...
#TX #Texas #ElPaso #Health #Toxic #Environment #Wellness — Grist (@grist.org) 2025-10-06T14:48:56.610Z
|
