Warmer oceans taking toll on world's coral reefs

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Warmer oceans taking toll on world's coral reefs
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Sun, 03-06-2011 - 2:37pm

Originally published Saturday, March 5, 2011 at 6:15 AM

Warmer oceans taking toll on world's coral reefs

Coral reefs are habitat for almost 100,000 known marine species, including about 40 percent of all fish species. They feed millions of people, protect coasts by absorbing wave energy, and shelter creatures that could become sources of medicine for treating cancer, HIV/AIDS and other diseases.

By Renee Schoof

McClatchy Newspapers

WASHINGTON — Global warming took a toll on coral reefs in 2010, endangering one of the world's key ecosystems that benefit people in countless ways.

Coral reefs are habitat for almost 100,000 known marine species, including about 40 percent of all fish species. They feed millions of people, protect coasts by absorbing wave energy, and shelter creatures that could become sources of medicine for treating cancer, HIV/AIDS and other diseases.

National Oceanic and Atmospheric Administration satellite data show that 2010, the warmest on record, was hard on corals. Warmer-than-normal temperatures stressed tropical corals, causing them to bleach — expelling the algae that live in their tissue, giving them color and nourishment.

Some 75 percent of the world's reefs are threatened by climate change, overfishing and pollution, according to a new assessment from the World Resources Institute and other conservation organizations. The number increased dramatically from the group's last assessment in 1998.

"It will take a Herculean effort to reverse the current trajectory and leave healthy ocean ecosystems to our children and grandchildren," said Jane Lubchenco, the marine scientist who heads NOAA. "How the world rises to this challenge is a reflection of our commitment to one another and to the natural world that gives us sustenance, wisdom and a reflection of our souls."

Coral reefs cover less than a tenth of 1 percent of the oceans' acreage, but that's still about 100,000 square miles. Scientists who dive to study reefs can't cover them all, so they're turning increasingly to satellites for help.

NOAA's satellite data on ocean heat shows that bleaching is occurring in all regions and becoming more frequent. Extreme bleaching kills corals because they can't survive without the nourishment the algae provide. Less-intense bleaching can weaken corals, reduce their growth and reproductive ability, and make them more vulnerable to disease.

Mark Eakin, a University of Miami-trained oceanographer who coordinates NOAA's Coral Reef Watch satellite program, said that 2010 was only the second time on record that bleaching occurred globally.

The first global bleaching, from 1997 to 1999, came when an exceedingly strong El Niño — a periodic warming of ocean surface temperatures in the tropical Pacific — was followed by an especially strong version of its opposite counterpart, La Niña. About 15 percent of the world's corals died then.

"Fast forward to 2010," Eakin said. This time, El Niño and La Niña weren't nearly as strong.

"The problem that we're seeing is, as the oceans keep warming on a year-to-year basis, it doesn't take as big or as unusual conditions to result in this sort of event."

The bleaching from last year in many places was the worst since 1998. In the warmest months, bleaching hit the Pacific, the Indian Ocean, Southeast Asia and the southern Caribbean.

The Florida Keys and the northern part of the Caribbean, where unprecedented bleaching occurred in 2005, were spared last year because tropical storms cooled the waters.

Coral reefs are more diverse in life forms than even rain forests are. The most abundant life is in the Coral Triangle, from the Philippines down to Indonesia and across to Papua New Guinea.

"I've been diving in some places there where I see more species on any given reef than we have in all of the Caribbean," Eakin said.

In Thailand, where he visited reefs last summer, nearly all were hit by bleaching.

Andrew Baird, a scientist at the Australian Research Council's Coral Reef Studies center, said he just returned from Indonesia's Aceh province, where nearly 100 percent of corals died at most sites. He said the total loss of coral cover could range from 50 to 80 percent.

"This is as bad as I have ever seen," Baird said. A similar level of bleaching is likely in Thailand and India, but it isn't nearly as bad elsewhere, he said.

Baird said it's highly likely that the most recent bleaching was connected to global warming.

"It's almost certainly the heat that was primarily responsible, but also low winds and therefore higher-than-usual penetration of sunlight could also have been involved," he said.

Ove Hoegh-Guldberg, the director of the Global Change Institute at the University of Queensland in Australia, said it's not surprising that the hottest year on record brought widespread coral bleaching and mortality. He said that scientists have reported that mass bleaching in the Philippines and Indonesia resulted in about 30-40 percent of the corals dying.

The accumulation of carbon dioxide, the primary heat-trapping gas contributing to global warming, also is expected to damage corals by making the oceans more acidic.

"To our knowledge, ocean acidification doesn't kill corals, but what it does is it makes them grow more slowly," Eakin said.

Carbon dioxide in the atmosphere is now higher than any time in 800,000 years.

"We probably sometime around the 1980s passed the levels that are conducive to coral-reef growth in terms of temperatures and CO2 in the atmosphere," Eakin said. "What we really need is to get back to where we were in the '80s."

That would mean reducing greenhouse gases to about 350 parts per million. It's 390 now and will be 560, or double preindustrial levels, by mid-century, according to the latest projections.

At that level, "We'll have major problems in reefs around the world," Eakin said.

"I don't think we're going to lose all corals, but we will probably lose species, and ecosystems will be severely degraded."

The World Resources Institute report projected that if current rates of greenhouse-gas emissions continue, about half of the world's reefs will suffer enough warming to cause severe bleaching most years in the 2030s, and 95 percent of them will in the 2050s.

http://seattletimes.nwsource.com/html/nationworld/2014403231_coralreefs06.html

 nwtreehugger  

iVillage Member
Registered: 02-05-2011
Coral survived the medieval warm period, and the Holocene maximum. They shouldn't have any problem with the current cooler climate.
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Registered: 03-18-2000
It appears in both instances cited, in your post, the increase in temps were not in the coral growing regions.

>"The Medieval Warm Period saw warm conditions over a large part of the North Atlantic, Southern Greenland, the Eurasian Arctic, and parts of North America. In these regions, temperature appears to be warmer than the 1961–1990 baseline. In some areas, temperatures were even as warm as today. However, certain regions such as central Eurasia, northwestern North America, and the tropical Pacific are substantially cooler compared to the 1961 to 1990 average."<
http://www.skepticalscience.com/medieval-warm-period-intermediate.htm

>"The Holocene Climate Optimum warm event consisted of increases of up to 4 °C near the North Pole (in one study, winter warming of 3 to 9 °C and summer of 2 to 6 °C in northern central Siberia).[1] Northwestern Europe experienced warming, while there was cooling in the south.[2] The average temperature change appears to have declined rapidly with latitude so that essentially no change in mean temperature is reported at low and mid latitudes. Tropical reefs tend to show temperature increases of less than 1 °C; the tropical ocean surface at the Great Barrier Reef ~5350 years ago was 1°C warmer and enriched in 18O by 0.5 per mil relative to modern seawater.[3] In terms of the global average, temperatures were probably colder than present day (depending on estimates of latitude dependence and seasonality in response patterns)."<
http://en.wikipedia.org/wiki/Holocene_climatic_optimum

 


Photobucket&nbs

iVillage Member
Registered: 02-05-2011

It turns out, we have been much warmer than today, and coral, polar bears, spotted owls, and the laundry list of endangered dainty animals have done fine. The most common state of our world for the past few million years has been ice age which means most of the time our world is much colder than today, and coral seems to even survive that. When I want non-biased science regarding a controversial issue, Wikipedia is not the place to go. Note 120,000-140,000 years ago, we had similar CO2 levels to today, I'm guessing coral did well there too.

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Registered: 02-15-2007

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Registered: 02-05-2011
Tom,

I agree. That the earth has been in an ice age for millions of years isn't in reasonable dispute. That we are in an interglacial epoch also isn't in dispute. That ocean levels have risen hundreds of feet, and global warming has been ongoing for 18,000 years isn't in dispute.

The controversy to the extent there is one, centers on anthropomorphic CO2 emissions and their effect on climate.

I believe it is better to pollute less, and if possible, to create less CO2. At the same time, I don't believe we should terminate our first world lifestyle which has produced more happiness, comfort, liberty and long life than any prior period of human existence.

Global warming has become very political, this has damaged the science. Until climate change becomes non-political, it is doubtful we will get good results.

As for peer review, there is evidence online that those favoring global warming theories conspired to undermine the peer review process. Those who have perpetrated fraud, and attempted to undermine peer review, are still in charge of their respective departments. Until that changes, we can't expect decent science on this subject.
iVillage Member
Registered: 02-15-2007

iVillage Member
Registered: 02-05-2011
Tom,

I think we more or less agree. Until the science of climate change becomes less political, it is doubtful we'll be getting much of anything useful out of it. Which is unfortunate.

One human trait, is to seek truth, and scientists generally try very hard to achieve this. Unfortunately global warming has become political and profitable. Instead of science, we seem to have snake oil.

In most cases where someone undermined or attempted to undermine, particularly in conspiracy with others, the peer review process, they would be shunned. This has no happened with the climate change institutes. Additionally the hockey stick, has been proved via freedom of information requests to be fraudulent. Also the "trick" of hiding a declining temperature graph behind other rising graphs, to fool readers is not worthy of any scientist I know of. There should be no need to fool people about results.

Raw data was either destroyed, or isn't generally available for true peer review by those who aren't supportive of global warming. Again, this is no science.

As a human, when looking at the many scientific failures which have occurred with respect to global warming science. It is clear that those supporting it aren't capable at this time of producing useful results. Until that changes, no action on CO2 or global warming should occur that interferes with economic progress.

We can hope that eventually politicians will get out of this science, and those who have provided deliberately misleading results can find other areas of gainful employment (like selling used cars).
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Registered: 02-15-2007