Page 249 - Microbial methane cycling in a warming world From biosphere to atmosphere Michiel H in t Zandt

TOP-DOWN
Field measurements Site sampling Field-based activity assay Lab-based activity assay Enrichment under climate scenarios (Meta)genomic species characterization Isolation & physiological characterization Assessment of ecosystem climate sensitivity
BOTTOM-UP
Physiological characterization & Assessment of contributions
Ecosystem reconstruction Complex synthetic cultures Co-cultures Pure cultures
Figure 2. Schematic overview of possible top-down and bottom-up approaches in microbiological studies of methane cycling microorganisms. The purple hourglass indicates the meeting point of both approaches in which an assessment of ecosystem climate sensitivity can be performed.
The Arctic regions are more vulnerable to climate change
The Arctic faces major environmental changes, even if all climate agreements would be met
today. In the last decades, air temperatures have increased about twice as fast in the Arctic as
in the mid-latitudes, a phenomenon that is known as the “Arctic amplification” (Graversen et 11 al. 2008). Pronounced and visible effects of warming in the Arctic include permafrost thaw,
melting of ice sheets, and sea level rise. These changes have been linked to increased microbial
activity and elevated GHG production that provide a positive feedback in global warming,
thereby amplifying these shifts.
In our study on long-term warming exposure on permafrost soils in Siberia, we observed functional changes in the transition layer and deeper permafrost that were linked to long-term methane emissions (Chapter 7). In the studies on thermokarst lakes of Utqiaġvik, Alaska, we observed rapid responses to increased temperatures and elevated substrate concentrations.
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