Posted by: climatewonk | February 25, 2008

Ocean Acidification

 Something that has always bothered me about skeptics who claim that increased CO2 will be good for us is their short-sightedness.  How do we know it will be good for us?  Isn’t the science as or even more uncertain in this regard?  Besides, no one ever seems to mention the effects of increased GHG, especially CO2, on the oceans, which are so important to our biosphere and to life on earth in general.  The link above leads to an article in Science Daily about the effects of global warming on the oceans.

 “Ocean ecosystems are facing new stresses and new combinations of stress,” Hofmann said. “The water is warmer, circulation patterns are changing in unpredictable ways, and oceans are becoming acidic.”

Rising greenhouse gas emissions are warming the world’s oceans and providing yet a new threat to coral reefs, which already are among the most threatened of all marine ecosystems, the panelists say. Even modest warming of a degree or two above normal maximum temperatures can cause a breakdown in the relationship between corals and their symbiotic algae, zooxanthellae, said Nancy Knowlton, a marine biologist with the Smithsonian Institution.

Without zooxanthellae corals appear white, or “bleached,” and grow more slowly. They also are more susceptible to disease and may not reproduce. In 1998 there were worldwide mass bleaching events, Knowlton pointed out, affecting 80 percent of the corals in the Indian Ocean, 20 percent of which died. In 2005, severe bleaching occurred over much of the Caribbean as a result of overly warm water temperatures.

“We have already lost some 80 percent of the reef corals in the Caribbean over the last three decades, and losses in the Pacific Ocean also are widespread and severe,” Knowlton said. “Reefs are like cities, with some parts growing and some parts being destroyed, and only when net growth is positive can reefs persist. These reefs already are under threat to overfishing and local pollution and unless drastic action to reduce greenhouse gas emissions is taken soon, these reefs will cease to exist as we know them.”

These same greenhouse gas emissions also are creating dramatic buildup of atmospheric carbon dioxide, which is rapidly making the world’s oceans more acidic, said panelist Scott Doney of the Woods Hole Oceanographic Institution. Current CO2 levels of 380 parts per million already are 30 percent higher than pre-industrial values and many scientific models predict that those rates will triple by the end of the century under “business as usual” scenarios.

 With no end in sight in terms of rising emissions worldwide, the future of the oceans looks grim.  I am dismayed to see so little concern on the part of those so-called skeptics for the state of the oceans.  They are so busy denying the science and trying to preclude any serious action to address GHG emissions, they are ignoring other issues besides temperature increase.  Even if warming turns out to be a bust, certainly increased CO2 emissions and ocean acidification are worthy of concern.


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