Warming may bring mass extinctions: study

Warming may bring mass extinctions: study

Wed. Oct. 24 2007
The Associated Press

WASHINGTON -- Whenever the world's tropical seas warm several degrees, Earth has experienced mass extinctions over millions of years, said a first-of-its-kind statistical study of fossil records.

And scientists fear it may be about to happen again -- but in a matter of several decades, not tens of millions of years.

Four of the five major extinctions over 520 million years of Earth history have been linked to warmer tropical seas, something that indicates a warmer world overall, said the study published Wednesday.

"We found that over the fossil record as a whole, the higher the temperatures have been, the higher the extinctions have been,'' said University of York ecologist Peter Mayhew, the co-author of the peer-reviewed research published in the Proceedings of the Royal Society B, a British journal.

Earth is on track to hit that same level of extinction-connected warming in about 100 years, unless greenhouse gas emissions are curbed, top scientists say.

A second study, to be presented at a scientific convention Sunday, links high carbon dioxide levels, the chief man-made gas responsible for global warming, to past extinctions.

In the British study, Mayhew and his colleagues looked at temperatures in 10-million-year chunks because fossil records aren't that precise in time measurements. They then compared those with the number of species, the number of species families and overall biodiversity. They found more biodiversity with lower temperatures and more species dying with higher temperatures.

The researchers examined tropical sea temperatures -- the only ones that can be determined from fossil records and go back hundreds of millions of years. They indicate a natural 60-million-year climate cycle that moves from a warmer "greenhouse'' to a cooler "icehouse.'' The Earth is warming from its current colder period.

Every time the tropical sea temperatures were about four degrees C warmer than they are now and stayed that way for millions of enough years, there was a die-off. How fast extinctions happen varies in length.

The study linked mass extinctions with higher temperatures but did not try to establish a cause-and-effect. For example, the most recent mass extinction, the one 65 million years ago that included the die-off of dinosaurs, probably was caused by an asteroid collision as scientists theorize and Mayhew agrees.

But extinctions were likely happening anyway as temperatures were increasing, Mayhew said. Massive volcanic activity, which releases large amounts of carbon dioxide, has also been blamed for the dinosaur extinction.

The author of the second study, which focuses on carbon dioxide, said he does see a cause-and-effect between warmer seas and extinctions.

Peter Ward, a University of Washington biology and paleontology professor, said natural increases in carbon dioxide warmed the air and ocean. The warmer water had less oxygen and spawned more microbes, which in turn spewed toxic hydrogen sulphide into the air and water, killing species.

Ward examined 13 major and minor extinctions in the past and found a common link: rising carbon dioxide levels in the air and falling oxygen levels. Ward's study will be presented Sunday at the Geological Society of America's annual convention in Denver.

Mayhew also found increasing carbon dioxide levels in the air coinciding with die-offs but concluded temperatures better predicted biodiversity.

Those higher temperatures that coincided with mass extinctions are about the same level forecast for a century from now if the world continues its growing emissions of greenhouse gases, the Nobel Prize-winning Intergovernmental Panel on Climate Change said.

In April, the same climate panel of thousands of scientists warned "20 to 30 per cent of animal species assessed so far are likely to be at increased risk of extinction'' if temperatures increase by about two degrees C.

"Since we're already seeing threshold changes in ecosystems with the relatively small amount of climate change already taking place, one could expect there's going to be severe transformations,'' said biologist Thomas Lovejoy, president of the H. John Heinz Center for Science, Economics and the Environment in Washington.

University of Texas biologist Camille Parmesan, who studies how existing species are changing with global warming but wasn't part of either team, said she was "blown away'' by the Mayhew study and called it "very convincing.''

"This will give scant comfort to anyone who says that the world has often been warmer than recently, so we're just going back to a better world,'' Pennsylvania State University geological sciences professor Richard Alley said.

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old news...."Four of the five major extinctions over 520 million years of Earth history have been linked to warmer tropical seas"

We really need a chicken little medal.

Well, I for one think this is going to happen at some point in the not too distant future. We just can't keep doing what we're doing and expect that they'll be no consequences. You keep peeing in the pool, pretty soon your swimming in piss.

Of course it is just like it has Four or five times over the last 520 million years , it is called a cycle.
The problem with technology is some times man thinks he's a little smarter then he is.

Some times? :lol:

Nature takes it course, always, and there is nothing we can do about it. Of course we can help make it worse, but nature will win... Mother Nature has the habit to addept to the situation, although that might not always be in the way mankind likes it.

If it is better for Mother Nature to get rid of people, there will be another killer desease...

imho that is.

Is it just me or did anyone else tumble to the fact that this goof has

1. Elaborated on many past warmings which were certainly lacking an anthropogenic cause.

2. Provided no proof of CO2 causation but cited theory...

3. Has assumed that the computer games are indeed accurate.

This typical "science". ROTFALMFAO

[font=Comic Sans MS] Pre-1492 the Indians had it good--fresh air nice land etc etc. Then aliens landed from Europe. A few hundered years later they started to infest the land by the 1800s. Then they called themselves Canadians and Americans. In less than 200 years these aliens have totally screwed the land over then they blame the indians for shooting one or two moose and catching "some salmon." Do any of you aliens ever stop and think about this? Opps I meant squatters and colonizers :wink:

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The last mass extiction in North America coincided with the arrival of Siberian Mongols in North America. Hmmm.... the Early Asian Immigrant myth of living in harmony with the land :roll:

. I've set my dogs on them when they try to hunt or fish illegally on MY land. :lol:

The way they ran you'd think they came from Kenya rather than Asia.