Existential importance for islands and coastal cities
Following the atmospheric warming, the ocean also warms globally and expands in the process. This thermal expansion is a major contributor to sea level rise, and increases drastically while emission reductions are delayed. "Until emission reductions start, the long-term thermal expansion increases even 7 to 25 times as fast as the now observed thermal expansion", Pfister cites from the study. A decade of delay in global emission reductions increases the long-term sea level rise by a total of roughly 0.4 to 1.2 meters, depending on the achievable rate of emission reductions. "For islands and coastal cities, the timing and rate of global emission reductions is therefore of existential importance", says Pfister. Furthermore, ongoing emissions also cause ocean acidification, with substantial impacts on marine ecosystems. For example, the acidification diminishes the extent of of ocean areas that provide ideal chemical conditions for the growth of tropical coral reefs. A near-complete loss of such areas becomes imminent if emission reductions are delayed by few years to decades, again depending on the achievable reduction rate.
"The results of our study underscore the urgency of action", says Thomas Stocker, co-author of the study and past Co-Chair of the Intergovernmental Panel on Climate Change. "With every decade of delaying global emission reductions, we lose roughly 0.5°C of climate target", Stocker remarks. This means that the most ambitious targets already become unachievable within the next few years.
(Source: University of Bern)