SAN FRANCISCO, June 8 (Xinhua) -- An international research team has evaluated 145 peer-reviewed studies and concluded that "highly protected" marine reserves can help mitigate the effects of climate change.
"Marine reserves cannot halt or completely offset the growing impacts of climate change," said Jane Lubchenco, a professor in the College of Science at Oregon State University (OSU) and co-author on a study published this week in Proceedings of the National Academy of Sciences. "But they can make marine ecosystems more resilient to changes and, in some cases, help slow down the rate of climate change.
Around the world, coastal nations have committed to protecting 10 percent of their waters by 2020, but thus far only 3.5 percent of the ocean has been set aside for protection, and 1.6 percent, or less than half of that, is strongly protected from exploitation. Some researchers have argued that as much as 30 percent of the ocean should be set aside as reserves to safeguard marine ecosystems in the long-term.
"Protecting a portion of our oceans and coastal wetlands will help sequester carbon, limit the consequences of poor management, protect habitats and biodiversity that are key to healthy oceans of the future, and buffer coastal populations from extreme events," Lubchenco, who previously worked as National Oceanic and Atmospheric Administration (NOAA) Administrator, was quoted as saying in a news release. "Marine reserves are climate reserves."
The authors say marine reserves can help protect ecosystems and people from five impacts of climate change that already are taking place: ocean acidification, rising sea levels, an increase in the severity of storms, shifts in the distribution of species, and decreased ocean productivity and availability of oxygen; and the benefits are greatest in large, long-established and well-managed reserves that have full protection from fishing and mineral extraction, and isolation from other damaging human activities.
The study notes that ocean surface waters have become on average 26 percent more acidic since pre-industrial times, and by the year 2100 under a "business-as-usual" scenario they will be 150 percent more acidic, while coastal wetlands, including mangroves, seagrasses and salt marshes, have demonstrated a capacity for reducing local carbon dioxide concentrations because many contain plants with high rates of photosynthesis.
Coastal wetlands, along with coral and oyster reefs, kelp forests and mud flats, can help ameliorate impacts of rising sea levels and storm surge. The average global sea level has risen about seven inches since 1900, and is expected to increase nearly three feet, or 0.9 meter, by the year 2100, threatening many low-lying cities and nations. The dense vegetation in coastal wetlands can also provide protection against severe storms, which are increasing in intensity in many parts of the world.
In addition, Climate change already is having a major impact on the abundance and distribution of marine species, the researchers say. Phytoplankton communities are changing in response to warming, acidification and stratifying oceans, and upper trophic level species are being affected, threatening global food security. Climate change interacts with and exacerbates other stressors like overfishing and pollution. Reducing some stressors can increase the resilience of species and ecosystems to impacts of other stressors.
"We have seen how marine reserves can be a haven for some species that are under duress from over-fishing or habitat loss, and as a 'stepping-stone' for other species that are recolonizing or moving into new areas," Lubchenco said. "Reserves enhance the resilience of marine ecosystems, and thus our resilience."