Soil in northern regions contains a lot of organic carbon. This can be released by warming. Earth scientist Han Dolman and ecologist Stef Bokhorst, together with other scientists, investigated how the carbon balance of northern ecosystems is affected by climate change.
It turns out that there is a difference between ecosystems with and without frost in the soil, which affects the amount of C02 in the atmosphere. Permanent frost in the ground is called permafrost. When permafrost thaws, microorganisms begin to break it down, releasing that carbon into the atmosphere as carbon dioxide, CO2, and methane. The balance between uptake by plants and release of CO2, can be disrupted by climate change. The research, published in Nature Climate Change, now shows that northern ecosystems without permafrost have increased their uptake of CO2 over time. Northern ecosystems where permafrost is still present in summer absorb proportionally less CO2. This means that some of the northern ecosystems are capturing CO2 from the atmosphere. As a result, greenhouse-driven global warming has increased less in recent years.
Necessity remains
But there will be a limit to this, and the necessity therefore remains to stop the CO2 concentration in the atmosphere from rising so much, and preferably get it lower. So to some extent, these ecosystems give us a bit of leeway to make changes in our activities that are going to ensure that we no longer have CO2 emissions.
Local factors
These patterns are additionally influenced by nutrient and water availability. So the effect of climate change on the carbon balance of northern ecosystems depends on several local factors. But the current study provides good insights into which ones these are, allowing better predictions to be made. For instance, if northern ecosystems absorb more, it is good news. But if this becomes less, it means that CO2 concentrations in the atmosphere increase even more, with all the consequences that entails. Including moving away from fossil fuels even faster. This therefore highlights the importance of long-term monitoring.
Collecting data
The researchers collected data from more than three hundred long-term monitoring points, and more than six hundred summer measurements, and measured C02 uptake and release. Bokhorst and Dolman contributed from VU University Amsterdam via data from their own research fields. For instance, the researchers have been taking measurements from Siberia and summer measurements from northern Scandinavia for almost two decades. Without this large number of measurement sites, it would not have been possible to unravel these subtle details.