Climate change could cause abrupt biodiversity losses

11Nov 2020
The Guardian
Climate change could cause abrupt biodiversity losses

The impacts of climate change on species and ecosystems are already evident. Projections indicate that unless emissions are rapidly reduced the climate crisis will get substantially worse. As ocean warming causes fish stocks to migrate toward cooler waters to maintain their-

-preferred thermal environment, many of the nations that rely on commercial fish species as an integral part of their economy could suffer.

A new study published in Nature Sustainability from the University of Delaware, the University of California, Santa Barbara and Hokkaido University, shows that nations in the tropics—especially Northwest African nations—are especially vulnerable to this potential species loss due to climate change. Not only are tropical countries at risk for the loss of fish stocks, the study found there are not currently any adequate policy interventions to help mitigate affected countries' potential losses.

The researchers used previously projected changes in the distribution range of 779 commercial fish species to estimate the number of species exiting national jurisdiction under contrasting emissions scenarios up to 2100.

Tropical nations in particular stand to lose the most species because there are few if any stocks to replace those leaving. Under a moderate emissions scenario, the research showed that by the year 2100, the average tropical nation could lose 7 percent of the species that were present in 2012.

While the exit of stocks from national fisheries is inevitable, carefully designed international cooperation could ease the impact on individual nations while preserving the resource for others. In addition to looking at the species loss, the researchers examined 127 international fisheries agreements, looking at the large, regional ones as well as smaller bi-lateral agreements. They found that none of the agreements have language that prepares countries for the exits of stock, climate change or range shifts.

Traditional fisheries management assumes that fish are a renewable natural resource and that so long as their geographic range is static, they will remain plentiful in the absence of overfishing. But the long-term migration of a species out of a country due to climate change means that fish stocks may not always be renewable on the level of a given jurisdiction, even if they remain renewable on an international scale. For the jurisdiction losing the stock, this creates an incentive to overfish before it exits.

How to handle liability for loss and damages from climate change—including whether countries that are more developed and have emitted more carbon dioxide should be compensating countries that are less developed—has been an ongoing discussion throughout the annual United Nations' Conference of the Parties (COP) meetings during which countries work to address climate change.

In the most recent COP 25 meeting in Madrid in December, compensation was again discussed, and the meeting highlighted the interplay between climate change and the ocean, but fisheries were not addressed.

While the Small Island Developing States have so far concentrated on concerns about becoming climate migrants as their land is overtaken by the ocean, Oremus said the study should encourage them and other tropical nations to bring fisheries into the conversation. For many nations where fish are one of the main economic resources driving their gross domestic product, this is something that they'll want to take into account when they join together to try and negotiate climate agreements.