Page 268 - Microbial methane cycling in a warming world From biosphere to atmosphere Michiel H in t Zandt

Chapter 11. Integration and outlook
people and destabilize societies (Renner 2008). The link with these severe and acute societal impacts is often forgotten when talking about global impacts of climate change.
Several communities are already suffering from severe consequences of global warming, which has forced people to leave their homes. For example, in Alaska, dozens of villages have had to relocate due to increasing danger of immediate flooding and erosion (GAO 2011). Due to rising sea levels, over 70,000 people will have to move in 2020 from the Sundarbans, a mangrove delta in the Bay of Bengal (Bhalla 2018). In Europe, the 2014 Balkan flooding, which has been linked to climate change, caused migratory movements of people from Bosnia and Herzegovina to other European countries (Montalto Monella 2020); and this is only the beginning. Environmental migration and disaster displacement will likely increase in the future (UNHCR 2020).
There is consensus in the climate science community about the reality of climate change, and there is near consensus on its severity and the broad range of attendant harms and risks (Dryzek, Norgaard and Schlosberg 2012). Consensus does not mean, however, that this scientific data are generally accepted as the basis for policy. A major challenge is that climate science does not provide certain future projections, but rather potential scenarios of risks and impacts to society. Although these effects were not the research focus of this thesis, they should be included in the scientific debate in which also researchers are involved.
Methane is an important target in greenhouse gas policy
Of the many targets to reduce human impacts on climate change, CH4 emissions are one of the most promising ones. This is mainly due to the short atmospheric lifetime of the CH4 molecule. As a consequence, reductions in CH4 emissions show rapid, beneficial climate effects. In addition, about two thirds of CH4 emissions are caused by human activities and impacts (Saunois et al. 2019). Therefore, changes in e.g. energy usage, infrastructure, and land use can strongly reduce CH4 emission into the atmosphere. However, not all processes can be easily controlled and several ecosystem-level processes are too heterogeneous and occur at too large a scale to be manageable.
We can also investigate the potentials to increase CH4 sinks, since CH4 feedbacks to the global climate are the net result of the balance between CH4 production and CH4 consumption (Fig. 1). In addition, biological and chemical CH4 oxidation processes are influenced by a wide
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