Did dinosaur 'emissions' help warm the prehistoric climate? (+video)
In a new study, scientists theorize that giant, vegetation-munching sauropods emitted nearly as much methane each year into the warm atmosphere as do all natural and industrial sources today.
Worried about about global warming and the methane that cattle burp into the air? Be glad Brontosaurus is extinct.Skip to next paragraph
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Sauropods – giant, long-necked, prehistoric vegans that roamed the planet for more than 100 million years through the end of the age of dinosaurs – released nearly as much methane into the atmosphere each year as do all natural and industrial sources today, according to an estimate from scientists in Britain.
The team, led by Liverpool John Moores University biologist David Wilkinson, suggests that methane emissions from sauropods could have played a key role in sustaining a climate already warmed by carbon-dioxide concentrations some 2 to 6 times higher than today.
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It was a world in which the poles were ice-free and crocodile-like creatures thrived in the Arctic. Scientists have pinned the high levels of carbon dioxide on widespread volcanic activity as plate tectonics rearranged continents.
CO2 and methane are both greenhouse-gases, with CO2 staying in the atmosphere far longer than methane. But while a newly minted methane molecule will remain airborne for only about 10 years, molecule for molecule, it is a far more potent greenhouse gas.
Back in the day, the warm wet climate and an atmosphere rich in CO2 would have turned much of the available land area into enormous smorgasbords, brimming with a wide variety of leafy treetops and fulsome shrubs – all within reach of the animals' long necks.
Estimating methane emissions “for animals that are unlike anything living has to be a bit of an educated guess,” Dr. Wilkinson cautions in a prepared statement. The fossil record has allowed researchers to infer a great deal about the physiology and biology of sauropods. But estimates of their ranges and the number that could inhabit the same square mile of land require a lot of assumptions.
Still, the estimate “makes a lot of sense,” says Felisa Smith, a biologist at the University of New Mexico in Albuquerque. Dr. Smith and colleagues published an estimate two years ago of the possible climate effect from methane lost to the atmosphere as large plant-eating mammals roaming North and South America went extinct. Smith and others point to the large-scale arrival of humans from Eurasia around 14,300 years ago as the extinction's main cause.