Climate-change driven stress to marine ecosystems could extend to over four-fifths of the world’s oceans by 2050 if no mitigating actions are taken, according to research published in Nature Communications. However, measures to slow the pace of climate change could extend stress-free conditions by 20 years, the study suggests, giving marine ecosystems more time to adapt to climate change.
Marine ecosystems provide the primary protein source for one in seven of the world’s population, yet the structure and functioning of this ecosystem is under threat from climate change. Marine ecosystem structure, functioning and capability to adapt is affected by four primary drivers, or stressors: pH, temperature, oxygen concentration and food availability. How the combined effects of these stressors will respond to future warming has been uncertain.
Stephanie Henson and colleagues use a group of numerical simulations to determine when the influence of climate change on these drivers leads to the emergence of conditions under which the marine ecosystem is unable to adapt and species migration is likely to occur. Under a business-as-usual scenario, the authors show that by 2050, conditions in 86% of the ocean will exceed natural variability, threatening the marine ecosystem as we know it. The authors also run their simulations under a mitigation scenario (based on Nationally Determined Contributions submitted during COP21) and show that if mitigating action is taken the proportion of ocean susceptible to multiple drivers within the next 15 years is reduced to 34%.
If implemented, such mitigating action could provide the marine ecosystem with enough time to respond to climate change, and protect human livelihoods and well-being, the authors conclude.