Oceans Would Perish Even If Levels of Atmospheric Carbon Were Reduced

While the “future dramatic removal of huge volumes of carbon dioxide from the atmosphere” could restore greenhouse gas concentrations to pre-industrial levels, the world’s oceans would “stay warmer, and more acidic, for thousands of years, and the consequences for marine life could be catastrophic” unless the burning of fossil fuels is stopped, reports The Guardian on findings by German scientists.

The research, published in Nature Climate Change [on Aug. 3] delivers yet another demonstration that there is so far no feasible “technofix” that would allow humans to go on mining and drilling for coal, oil and gas (known as the “business as usual” scenario), and then geoengineer a solution when climate change becomes calamitous. …

“Interestingly, it turns out that after ‘business as usual’ until 2150, even taking such enormous amounts of CO2 from the atmosphere wouldn’t help the deep ocean that much – after the acidified water has been transported by large-scale ocean circulation to great depths, it is out of reach for many centuries, no matter how much CO2 is removed from the atmosphere,” said a co-author, Ken Caldeira, who is normally based at the Carnegie Institution in the US.

The oceans cover 70% of the globe. By 2500, ocean surface temperatures would have increased by 5C and the chemistry of the ocean waters would have shifted towards levels of acidity that would make it difficult for fish and shellfish to flourish. Warmer waters hold less dissolved oxygen. Ocean currents, too, would probably change.

But while change happens in the atmosphere over tens of years, change in the ocean surface takes centuries, and in the deep oceans, millennia. So even if atmospheric temperatures were restored to pre-Industrial Revolution levels, the oceans would continue to experience climatic catastrophe.

“In the deep ocean, the chemical echo of this century’s CO₂ pollution will reverberate for thousands of years,” said co-author Hans Joachim Schellnhuber, who directs the Potsdam Institute for Climate Impact Research. “If we do not implement emissions reductions measures in line with the 2C target in time, we will not be able to preserve ocean life as we know it.”

Read more here.

— Posted by Alexander Reed Kelly.