Contribution article by Ville Uusitalo, Assistant Professor at the LUT-University (School of Energy Systems, Sustainable Science) and Annamari Enström, Senior Researcher, LCA at Neste Corporation.
Global warming impacts of different products and processes from life cycle assessment (LCA) perspective is widely performed with standardized methods. Global warming impact assessments in LCA are, typically, carried out by using GWP factors for different greenhouse gas emissions. However, there are also multiple additional indirect impacts to global warming through impacts of these emissions. This paper shortly discusses a possibility to include also these indirect impacts to future GWP assessments using methane release from permafrost regions as an example. Similar indirect impacts (both positive and negative) are also caused e.g. through soil carbon losses due to desertification and higher carbon sequestration of forests due to warmer climate. There are also other indirect impacts from climate change in addition to global warming such as temperature rise, changes in rain patterns, ocean acidification, extreme weather events, and rising sea levels.
Figure 1. presents a basic idea of how greenhouse gas emissions indirectly impact on methane release from permafrost regions through global warming. This leads to additional global warming impacts, which are not currently included in GWP factors. The author is aware that there are probably challenges in creating this kind of indirect additions due to lack of exact data. To tackle climate challenges, understanding of these processes would be crucial. As far as the authors of this draft document are aware, these secondary or indirect impacts have not yet been holistically studied and assessed although individual studies are available which monetize or otherwise measure the impacts of climate change.
Greenhouse gas emissions lead to additional GWP impacts e.g. through methane release from arctic seas and soil by melting permafrost and by increasing water temperature
According to Marzeion, et al. (2018), 1 kg of CO2 in the atmosphere is able to melt 15 kg of glacier ice within 100 years period. According to EPA (2016), warming in the Arctic leads to permafrost thaw, which can increase soil carbon dioxide and methane emissions, thereby contributing to further warming.
However, there is still a lack of knowledge on how global warming impacts on methane release. According to measures by Shakhova et al. (2014), partially thawed permafrost injected 100–630 mg methane m−2 d−1 into the overlying water column. Shakhova et al. (2010A) fears that remobilization to the atmosphere of only a small fraction of the methane held in East Siberian Arctic Shelf (ESAS) sediments could trigger abrupt climate warming. They show that more than 5000 at-sea observations of dissolved methane demonstrates that high shares of ESAS waters are supersaturated with methane. Shahkova et al. (2010B) found CH4 that probably originates from seabed CH4 reservoirs such as shallow hydrates and geological sources. This points to permafrost’s failure to further preserve CH4 deposits. The total amount of carbon pres