There is hope that microalgae inhabiting peatlands will absorb more and more carbon dioxide as the temperature increases. They may not stop climate change, but they will be our allies in the fight against global warming. So far, research has ignored the role of this group of organisms in climate analyses.
'Our study shows that there is still a part of the carbon cycle that has been very poorly understood', comments Professor Mariusz Lamentowicz from the Adam Mickiewicz University, co-author of the European research project.
Microalgae are photosynthetic microorganisms. They may be associated with lakes, but they also inhabit the soil and the top layer of peatlands.
'You can imagine that on the top layer of peatland dominated by peat mosses there is a green mat of photosynthetic organisms that is several centimetres thick. For example, one gram of dry mass of mosses can contain between 10,000 and a million microalgae', Lamentowicz explains. These include cyanobacteria, diatoms, green algae, but also algae inhabiting shelled amoebas. While some peatland microorganisms release CO2 in the process of respiration, microalgae absorb it in the process of photosynthesis. Rising temperatures stimulate the photosynthesis of these microorganisms, thus increasing the ability of peatlands to capture carbon dioxide.
Professor Mariusz Lamentowicz adds that microalgae are a part of the peatland microbiome, but so far their role in absorbing carbon dioxide has been underestimated. 'If the peatlands of the northern hemisphere are in good condition, the increase in the activity of photosynthetic microorganisms there could increase carbon absorption by 28.6 million tons per year by 2100. We show that this group of organisms are important players in global warming', Lamentowicz says.
Microalgae will absorb more CO2 than they do today, so they will be our allies in climate change. Unfortunately, the additional possibilities that we will gain thanks to them will not be enough to absorb excess CO2 on an ongoing basis. These same climate changes will also lead to more microorganisms in the environment that decompose organic matter. And those will introduce more than 6 times more CO2 into the environment than the microalgae will be able to remove. We can therefore consider microalgae to be our helpers, but unfortunately, they will not be heroes who will save us from further temperature increases.
To check how the role of microalgae in the accumulation of greenhouse gases will change, the scientists organized a kind of Erasmus for microalgae. Four peatlands from places with different climates were analysed: in the Pyrenees (Counozouls), Poland (Kusowo Bog), Estonia (Mannikjarve), northern Sweden (Abisko). Cuttings of the topsoil taken from each of these places were transplanted to the remaining sites. In this way, the researchers checked how the organisms would cope if the climate at each site were to change into the model of the Estonian, Polish, Swedish or French climates. Microalgae from colder places coped better in warmer places. This gives hope that they will also cope with rapid climate changes for some time.
Previous climate forecasts did not take this mechanism into account due to a lack of data, but the latest research confirms that the photosynthesis process of microalgae can contribute to mitigating climate change. However, many aspects of carbon assimilation by peatland microorganisms remain unknown. Further research is necessary to precisely determine the potential of these ecosystems as CO2 sinks, and to improve climate models.
However, for microalgae to help us remove CO2 from the atmosphere, peatlands must remain in good condition. The carbon they accumulate must remain in the peat. In destroyed peatlands, deprived of water, the abundance of these microorganisms is much lower. 'We should all the more strive to restore peatlands and irrigate them. And detailed scientific knowledge of the processes occurring in peatlands helps us to better understand how to protect peatlands', Professor Mariusz Lamentowicz concludes.
Despite the optimistic results of the study, the scientists emphasise that it does not undermine the growing CO2 emissions since the pre-industrial era and their negative consequences. Protection of peatlands and global reduction of carbon dioxide emissions remain key strategies in the fight against ongoing climate change.
PAP - Science in Poland, Ludwika Tomala
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