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Freshwater methane emissions maximised by global warming
https://www.qmul.ac.uk/news/latest-news/2026/science-and-engineering/se/freshwater-methane-emissions-maximised-by-global-warming-.htmlIt is not just cows that emit the powerful greenhouse gas methane – microbial emissions from the natural world will inevitably increase as our planet continues to warm.
5 June 2026
…
Say ‘methane’ and most people think of cows, yet nearly half of all methane is produced by microbes in the natural world, especially lakes, ponds and wet soils. How much methane reaches our atmosphere depends on a balance between the production of methane by one type of microbe and the consumption of methane by another type. We know in a simple sense that these methane related microbes are stimulated by warming, but how both types will respond to warming over the next century is unknown.
The scientists used a unique natural experiment spanning the northern hemisphere to test the effect of warming on the methane balance over centuries to millennial time scales that is, after plenty of time for the microbes to adjust to climate change. They used samples collected from naturally warmed streams in remote parts of Alaska, Greenland, Iceland, Svalbard and Kamchatka (Russia). They showed that while methane consuming microbes do work harder under warmer conditions, they cannot fully check the extra methane being produced with warming. Worryingly this new study thus describes a seemingly inevitable increase in methane emissions as Earth continues to warm, building a positive feedback loop through climate change and still higher temperatures.
…
And Professor Gabriel Yvon-Durocher of the University of Exeter said “What is remarkable is that despite the complexity of microbial processes involved in the emission of methane from natural ecosystems, we find the same strong temperature sensitivity among the diversity of geothermally heated freshwaters across the Arctic region”.
This methane research formed part of a wider project led by Professor Guy Woodward of Imperial College and Professor Alex Dumbrell of the University of Essex who said: “We have now shown how the combined effects of warming has contrasting effects on microbes that produce methane versus those that consume it - this new insight required a uniquely ambitious genes-to-ecosystems field campaign, which spanned intercontinental scales”.
Harpenslager, S.F., Randall, K., Zhu, Y. et al. A fixed methane filter maximizes freshwater emissions under warming. Nat. Clim. Chang. (2026). https://doi.org/10.1038/s41558-026-02649-2
5 June 2026
…
Say ‘methane’ and most people think of cows, yet nearly half of all methane is produced by microbes in the natural world, especially lakes, ponds and wet soils. How much methane reaches our atmosphere depends on a balance between the production of methane by one type of microbe and the consumption of methane by another type. We know in a simple sense that these methane related microbes are stimulated by warming, but how both types will respond to warming over the next century is unknown.
The scientists used a unique natural experiment spanning the northern hemisphere to test the effect of warming on the methane balance over centuries to millennial time scales that is, after plenty of time for the microbes to adjust to climate change. They used samples collected from naturally warmed streams in remote parts of Alaska, Greenland, Iceland, Svalbard and Kamchatka (Russia). They showed that while methane consuming microbes do work harder under warmer conditions, they cannot fully check the extra methane being produced with warming. Worryingly this new study thus describes a seemingly inevitable increase in methane emissions as Earth continues to warm, building a positive feedback loop through climate change and still higher temperatures.
…
And Professor Gabriel Yvon-Durocher of the University of Exeter said “What is remarkable is that despite the complexity of microbial processes involved in the emission of methane from natural ecosystems, we find the same strong temperature sensitivity among the diversity of geothermally heated freshwaters across the Arctic region”.
This methane research formed part of a wider project led by Professor Guy Woodward of Imperial College and Professor Alex Dumbrell of the University of Essex who said: “We have now shown how the combined effects of warming has contrasting effects on microbes that produce methane versus those that consume it - this new insight required a uniquely ambitious genes-to-ecosystems field campaign, which spanned intercontinental scales”.
https://www.qmul.ac.uk/news/latest-news/2026/science-and-engineering/se/behind-the-research-freshwater-methane-emissions-maximised-by-global-warming-.html
Behind the research: Freshwater methane emissions maximised by global warming
This "behind-the-research" blog by Mark Trimmer, Professor of Biogeochemistry, takes readers beyond the published findings to reveal the motivations, challenges, and human stories that shaped the study.
5 June 2026
…
How much methane is released into our atmosphere from freshwaters depends on the balance between its production and consumption by two distinct groups of microbes. While we already know that microbes are stimulated by warming i.e., they respire harder at higher temperatures, it is far more challenging to determine how global climate warming will affect the balance between methane production and consumption in the long term. Here we used a unique natural experiment spanning the northern hemisphere to test the effect of warming on methane emissions over centuries to millennial time scales. We used collections of geothermally warmed streams, spanning parts of Alaska, Greenland, Iceland, Svalbard and Kamchatka. The studied streams are indirectly warmed through the bedrock and so are distinct from the harsh environment of their cousins in Yellow Stone Park, for example. Our natural experiment enabled us to measure methane production, consumption and emission and the associated microbes in an environment where they have had plenty of time “to adjust” to warmer conditions, thereby mimicking the long-term effect of climate change. We show that while warmer methane consuming microbes do work harder, they cannot fully counter the extra methane being produced with warming. Our study thus describes a seemingly inevitable increase in methane emissions as Earth continues to warm, building a positive feedback loop into climate change.
The remoteness of our high-latitude study sites ensured we could separate the effect of temperature from, for example, human pollution on methane emissions – but that remoteness came with challenges. While Iceland is a short hop from Heathrow, our sites in Kamchatka, Alaska and Greenland were not just “down the road” and simply getting to these remote locations required combinations of small planes, boats, cars and sturdy hiking boots. Navigating customs to get our equipment crates and samples through could be a challenge, as was the acquisition of chemicals, such as ethanol, nitrogen gas and liquid nitrogen. Although a previous expedition had broadly scouted our sampling locations, the precise location of individual streams was often a bit vague as their GPS coordinates had not been recorded! Rather, in Alaska, we were left to pursue a “treasure map” with streams marked by "landmarks” such as “Mad dog house” and “Man at airport's house”! The physical demand of trekking several miles on rough terrain to sample a stream with heavy field kit was also intense.
Besides, working in the Arctic comes with its own challenges. Fingers go numb when working downwind from a glacier in the rain in Iceland. Mosquitos and black flies make life miserable, as every bit of exposed skin is attacked. Bear encounters are a real threat in Alaska, Kamchatka and especially Svalbard. To protect us from polar bears, we had polar bear guards and received rifle training for extra protection. Luckily, we only encountered bears from a safe distance. In Kamchatka, we were stranded on a dirt road with a flat tyre (one of many) while bears had been spotted in the area, but our loud singing must have kept them at bay. In Greenland and Svalbard, a boat was needed to reach our sites but a miscalculation of tide times - was it the Captain? - in Greenland meant being stranded for hours in the cold on a remote beach with minor provisions and limited heat source. On our next outing, we made sure to bring tents and provisions! In Svalbard, we had to navigate our small sailing boat through fields of ice sheets, while on the return journey we were forced to shelter for 8 hours from a vicious storm.
…
This "behind-the-research" blog by Mark Trimmer, Professor of Biogeochemistry, takes readers beyond the published findings to reveal the motivations, challenges, and human stories that shaped the study.
5 June 2026
…
How much methane is released into our atmosphere from freshwaters depends on the balance between its production and consumption by two distinct groups of microbes. While we already know that microbes are stimulated by warming i.e., they respire harder at higher temperatures, it is far more challenging to determine how global climate warming will affect the balance between methane production and consumption in the long term. Here we used a unique natural experiment spanning the northern hemisphere to test the effect of warming on methane emissions over centuries to millennial time scales. We used collections of geothermally warmed streams, spanning parts of Alaska, Greenland, Iceland, Svalbard and Kamchatka. The studied streams are indirectly warmed through the bedrock and so are distinct from the harsh environment of their cousins in Yellow Stone Park, for example. Our natural experiment enabled us to measure methane production, consumption and emission and the associated microbes in an environment where they have had plenty of time “to adjust” to warmer conditions, thereby mimicking the long-term effect of climate change. We show that while warmer methane consuming microbes do work harder, they cannot fully counter the extra methane being produced with warming. Our study thus describes a seemingly inevitable increase in methane emissions as Earth continues to warm, building a positive feedback loop into climate change.
The remoteness of our high-latitude study sites ensured we could separate the effect of temperature from, for example, human pollution on methane emissions – but that remoteness came with challenges. While Iceland is a short hop from Heathrow, our sites in Kamchatka, Alaska and Greenland were not just “down the road” and simply getting to these remote locations required combinations of small planes, boats, cars and sturdy hiking boots. Navigating customs to get our equipment crates and samples through could be a challenge, as was the acquisition of chemicals, such as ethanol, nitrogen gas and liquid nitrogen. Although a previous expedition had broadly scouted our sampling locations, the precise location of individual streams was often a bit vague as their GPS coordinates had not been recorded! Rather, in Alaska, we were left to pursue a “treasure map” with streams marked by "landmarks” such as “Mad dog house” and “Man at airport's house”! The physical demand of trekking several miles on rough terrain to sample a stream with heavy field kit was also intense.
Besides, working in the Arctic comes with its own challenges. Fingers go numb when working downwind from a glacier in the rain in Iceland. Mosquitos and black flies make life miserable, as every bit of exposed skin is attacked. Bear encounters are a real threat in Alaska, Kamchatka and especially Svalbard. To protect us from polar bears, we had polar bear guards and received rifle training for extra protection. Luckily, we only encountered bears from a safe distance. In Kamchatka, we were stranded on a dirt road with a flat tyre (one of many) while bears had been spotted in the area, but our loud singing must have kept them at bay. In Greenland and Svalbard, a boat was needed to reach our sites but a miscalculation of tide times - was it the Captain? - in Greenland meant being stranded for hours in the cold on a remote beach with minor provisions and limited heat source. On our next outing, we made sure to bring tents and provisions! In Svalbard, we had to navigate our small sailing boat through fields of ice sheets, while on the return journey we were forced to shelter for 8 hours from a vicious storm.
…