Microbes across Earth’s coldest regions are becoming more active as glaciers, permafrost and sea ice thaw, accelerating carbon release and potentially amplifying climate change, according to a new international review from McGill University. 

Drawing on data from polar and alpine environments worldwide, the researchers found that warming is driving faster microbial metabolism, increasing the breakdown of organic matter and the release of greenhouse gasses such as carbon dioxide and methane into the atmosphere. Thawing soils may also free such contaminants as mercury, with implications that extend well beyond polar regions as harmful substances spread through rivers and food webs. 

“Cold-climate microbial ecosystems are poised for rapid change,” said Scott Sugden, study co-author and a doctoral student with the Polar Microbiology Lab led by Professor Lyle Whyte in the Department of Natural Resource Sciences. “We know these changes will have significant consequences not only for the global carbon cycle, but also for human communities, food and income security, and toxin release. Yet these ecosystems are changing more quickly than they’re being understood.” 

Why thaw matters for microbes 

The review synthesized dozens of studies from Arctic, Antarctic, alpine and subarctic environments to assess how temperature and nutrient availability are shaping microbial activity. 

Across regions, the researchers identified two consistent patterns: in frozen environments, microbial processes are constrained by both food and temperature. As soils thaw and nutrients move more freely through runoff, those constraints ease, allowing microbes to become more active, speed up carbon cycling and release stored contaminants. 

“These two general truths about food and temperature emerged consistently across dozens of studies, dozens of ecosystems,” Sugden said. 

The review also points to factors that can further influence outcomes, including oxygen availability and whether thawed landscapes become wetter or drier – conditions that can significantly alter how microbial communities behave. 

Data gaps limit climate predictions 

While microbial processes are increasingly recognized as an important driver of climate feedback loops, the researchers noted that polar microbiology remains a relatively young field, with only about two decades of baseline data. These gaps make it difficult to project long-term climate impacts accurately. 

“Unlike other fields where you can look back at a documented species over centuries, we don’t have that long time horizon. Our first pieces of data come from the early 2000s,” Sugden said. 

The review identified three additional limitations: 

  • Research tends to cluster in accessible regions with established infrastructure, leaving large parts of the Arctic and Antarctic understudied; 
  • Extreme weather and limited daylight restrict winter fieldwork; and 
  • Short-term funding often limits studies to only a few years, obscuring long-term trends. 

To improve climate projections, the authors call for greater coordination of global monitoring efforts and greater use of low-cost, widely accessible data collection methods. 

“We can’t demand millions of dollars to study every site. But if you’re a polar researcher, you could bring a thermometer to the field. These small, consistent data points can make a big difference,” said Christina Davis, study co-author and postdoctoral researcher in Astrobiology and Extraterrestrial Biosignatures. 

“More data of any kind is good data,” Sugden added. 

About this study

“Current and future effects of climate change in cryosphere microbial ecosystems,” by Scott Sugden, Christina L Davis, Matthew W. Quinn and Lyle G. Whyte, was published in Nature Reviews – Microbiology. 

The study was funded by the Natural Sciences and Engineering Council of Canada, the Canada Research Chair Program and the Canadian Space Agency.