Ocean poverty: warming seas will affect poorest first

LONDON—Greenhouse-gas emissions from industry and power generation have begun to trigger ocean changes that will impose huge costs to the poorest people on the planet.

Only in the polar regions would there be any increase in productivity or in oxygen levels. Nowhere would there be any cooling.

These changes are likely to cascade through marine ecosystems and habitats to the deep ocean itself and to affect humans along the way, according to a report published recently in the journal Public Library of Science Biology.

“The consequence of these co-occurring changes are massive: everything from species survival to abundance to range size to body size to species richness to ecosystem functioning are affected by changes in ocean biogeochemistry,” said Camilo Mora, a geography professor at the University of Hawaii and lead author on the paper.

Mora and fellow data analysts made headlines earlier this month by calculating the year in which any given location on Earth was likely to experience dramatic and inexorable climate change: the researchers arrived at a mean date of 2047 (give or take six years on either side) for change, with the first impact in West Papua by 2020.

Global view

The recent report once again takes a global view of change on this blue planet. The researchers calculated the effect of two scenarios for the future: one in which the world rapidly tries to reduce emissions, and the notorious business-as-usual scenario, which will take carbon-dioxide concentrations to the unprecedented level of 900 parts per million by 2100.

Then they contemplated the impact on 32 marine habitats and biodiversity hotspots, and then they examined the available data on human dependence on the ocean.

They found that most of the world’s ocean surface would feel the heat. Only in the polar regions would there be any increase in productivity or in oxygen levels. Nowhere would there be any cooling, and pH levels would trend toward acidification everywhere.

Chopping the base of the food chain

By 2100 global averages for the upper layer of the ocean would increase by between 1.2° C and 2.6° C. Dissolved-oxygen concentrations would, on average, fall by between two percent and four percent, and phytoplankton production would diminish by between four percent and 10 percent.

Phytoplankton are the base of the ocean food chain; such a reduction would chop overall yield for between 470 and 870 million people who make a precarious and meagre living from the sea, they estimated.

“The impact of climate change will be felt from the ocean surface to the sea floor,” said Andrew Sweetman, a coauthor, now at the International Research Institute of Stavanger, Norway. “It is truly scary to consider how vast these impacts will be. This is one legacy that we, as humans, should not be allowed to ignore.”