A new study has taken up the ambitious task of predicting a full chain of events - beginning with our current chemical impact on the ocean - to forecast the state of the sea in a hundred years from now.

The study published overnight in the open access journal PLOS Biology says that the ocean biogeochemical changes that are predicted to be triggered by manmade greenhouse gas emissions over the next 100 years will filter down through marine habitats and organisms, penetrating the deep ocean and eventually influencing humans.

Several efforts have been made previously to gauge the effects of ocean warming and acidification on its own internal workings, but some say these have underestimated the fuller biological and social consequences of the climatic change.

The new study has expanded the scope somewhat, concluding that in 2100; no part of the world’s ocean will remain unaffected by climate change.

It is the first to factor-in predictable related changes such as the depletion of dissolved oxygen in seawater and a decline in productivity of ocean ecosystem.

“When you look at the world ocean, there are few places that will be free of changes; most will suffer the simultaneous effects of warming, acidification, and reductions in oxygen and productivity,” said lead author Camilo Mora, assistant professor at the Department of Geography in the College of Social Sciences at the University of Hawai'i at Mānoa.

The human ramifications will be dire, predictions say. Food chains, fishing, and tourism would all feel impacts, including the 470 to 870 million of the world's poorest people who rely on the ocean for food, jobs, and revenues and live in areas which will be compromised by multiple ocean biogeochemical changes.

The researchers used the same models for the projections that were employed by the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) to inform their analysis.

Co-author Lisa Levin, a professor at Scripps Institution of Oceanography at the University of California, San Diego, says there is hardly room to mess around in the fragile depths of the ocean

“Because many deep-sea ecosystems are so stable, even small changes in temperature, oxygen, and pH may lower the resilience of deep-sea communities. This is a growing concern as humans extract more resources and create more disturbances in the deep ocean,” Levin says.

“The impacts of climate change will be felt from the ocean surface to the seafloor. It is truly scary to consider how vast these impacts will be,” said co-author Andrew K. Sweetman of the International Research Institute of Stavanger in Norway.

“This is one legacy that we as humans should not be allowed to ignore.”

A expanded synopsis of the report and full details are both available via the journal PLOS Biology.