The last time this happened, we lost almost a fifth of world reefs.
“Coral reefs cover just 0.1 percent of the ocean floor, but provide habitat to 25 percent of sea-dwelling fish species. That’s why coral scientist C. Mark Eakin, who coordinates the National Oceanic and Atmospheric Administration’s Coral Reef Watch program, is surprised that the warning he has been sounding since last year (PDF)—that the globe’s reefs appear to be on the verge of a mass-scale bleaching event—hasn’t drawn more media attention.
“Bleaching happens when coral loses contact with zooxanthellae, an algae that essentially feeds them nutrients in symbiotic exchange for a stable habitat. The coral/zooxanthellae relationship thrives within a pretty tight range of ocean temperatures, and when water warms above normal levels, coral tends to expel its algal lifeline. In doing so, coral not only loses the brilliant colors zooxanthellae deliver—hence, “bleaching”—but also its main source of food. A bleached coral reef rapidly begins to decline. Coral can reunite with healthy zooxanthellae and recover, Eakin says, but even then they often become diseased and may die. That’s rotten news, because bleaching outbreaks are increasingly common.” Source: www.motherjones.com
GR: This post is about CO2 and ocean acidification. Other blog posts about plastic in the oceans, overfishing, garbage dumping, and toxic runoff suggest that the cost of the human impact on oceans will be far greater than the trillion dollars estimated by the UN Convention on Biological Diversity. Those costs are based on short-term factors. Species extinction is permanent. Recovery of biodiversity will take millennia. Some would say that causing the loss of a single species is unacceptable. So once again, I have to say that we must push harder. Sign those petitions, take time for the rallies and marches, send letters, make phone calls, join local groups, and enter local politics.
The following from Robert Scribbler.
“Ecosystems that have thrived and developed over millions of years are being smashed down by human activities in just a few decades. It is a very sad state of affairs that hopefully we can turn around before it is too late.” — Ken Caldeira of Stanford University.
“One trillion dollars. That’s the economic impact a new UN study found resulting from the world’s oceans becoming 170 percent more acidic by 2100 under an inexorable and ongoing human carbon emission.
“It’s a rapidly ramping acidity that is being driven by an ever-rising level of CO2 in the Earth’s atmosphere. An emission that is already setting the stage for a first wave of mass extinction in the world ocean — starting now and hitting high gear once global CO2 levels reach about 500 parts per million (this year, global CO2 levels topped off at 401 parts per million and under current and planned emissions are likely to hit 500 ppm within about 30 years).
“At issue is the vulnerability of coral reefs and many other species with calcareous skeletons and shells to rapid acidification. In the deep geological past, we’ve seen mass extinctions in many of these species due to rapid rises in ocean acidity. Events such as the Permian and PETM extinctions all showed terrible losses of species due to ocean acidification alone.
“But the pace at which humans are increasing ocean acidification has never been seen before in the geological record. So the blow that is coming to many of the animals we rely on is worse than anything that happened in Earth’s past.
“(Ocean acidification and related impacts to coral reefs through 2050 [500 ppm CO2]. Image source: Threat to Coral Reefs From Ocean Acidification.)”
Read more . . . .
As pointed out before, CO2 emissions do more than affect the atmosphere.
Drawing from NOAA PMEL Carbon Program
“When seawater absorbs carbon dioxide (CO2), chemical reactions cut seawater pH, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals. Calcium carbonate minerals are the building blocks for the skeletons and shells of many marine organisms. In areas where most life now congregates in the ocean, the seawater is supersaturated with calcium carbonate minerals. This means there are abundant building blocks for organisms to build their skeletons and shells. However, continued ocean acidification is causing many parts of the ocean to become unsaturated and some organisms will have difficulty producing and maintaining their shells” (NOAA).
“The skeleton hand of ocean acidification has been found at work near one of Australia’s most exotic tropical destinations, Lizard Island on the Great Barrier Reef.
“Scientists surveying a reef flat just south of the resort island, off Cooktown, have measured a near 40 per cent calcium carbonate decline.”
Read more at “The Age.”