Bacteria may contribute more to climate change as planet heats up

By releasing more carbon as global temperatures rise, bacteria and related organisms called archaea could increase climate warming at a faster rate than current models suggest. The new research, published today in Nature Communications by scientists from Imperial College London, could help inform more accurate models of future climate warming.

Bacteria and archaea, collectively known as prokaryotes, are present on every continent and make up around half of global biomass -- the total weight of all organisms on Earth.

Most prokaryotes perform respiration that uses energy and releases carbon dioxide -- just like we do when we breathe out. The amount of carbon dioxide released during a given time period depends on the prokaryote's respiration rate, which can change in response to temperature.

However, the exact relationship between temperature, respiration rate and carbon output has been uncertain. Now, by bringing together a database of respiration rate changes according to temperature from 482 prokaryotes, researchers have found the majority will increase their carbon output in response to higher temperatures to a greater degree than previously thought.

Lead researcher Dr Samraat Pawar, from the Department of Life Sciences at Imperial, said: "In the short term, on a scale of days to hours, individual prokaryotes will increase their metabolism and produce more carbon dioxide. However, there is still a maximum temperature at which their metabolism becomes inefficient.

"In the longer term, over years, these prokaryote communities will evolve to be more efficient at higher temperatures, allowing them to further increase their metabolism and their carbon output.

"Rising temperatures therefore cause a 'double whammy' effect on many prokaryote communities, allowing them to function more efficiently in both the short and long term, and creating an even larger contribution to global carbon and resulting temperatures."