Environment

World's reservoirs pumping out more greenhouse gas than Canada, study finds

World's reservoirs pumping out...
Reservoirs are emitting 25 percent more methane than we previously thought, the new study has found
Reservoirs are emitting 25 percent more methane than we previously thought, the new study has found
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Reservoirs are emitting 25 percent more methane than we previously thought, the new study has found
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Reservoirs are emitting 25 percent more methane than we previously thought, the new study has found

Fossil fuels, agriculture and transportation are examples of well-known sources when it comes to greenhouse gas emissions and a changing climate, but a new study suggests there may be an additional silent contributor in our midst. Environmental scientists tracking greenhouse gases rising from the world's reservoirs say they produce the equivalent of around one gigaton of carbon dioxide each year, more than all of Canada, and a figure not currently taken into account when sizing up our environmental footprint.

Scientists have known for some time that reservoirs play a role in global warming. The difference between these and natural bodies of water is in what lies beneath, with the construction of manmade reservoirs usually flooding soil and vegetation rich with organic matter. When these nutrients are decomposed by microbes, they are transformed into carbon dioxide, methane and nitrous oxide and flow upwards into the atmosphere.

Researchers have monitored this phenomenon over the last 15 years or so, but a paper to be published this week by scientists at Washington State University will be the largest and most comprehensive to date. The team has gone over the previous literature and synthesized a large number of studies, concluding that not only are these emissions equal to 1.3 percent of the global total, but the particularly potent greenhouse gas methane is a bigger part of the picture than previously suspected.

"We had a sense that methane might be pretty important but we were surprised that it was as important as it was," says Bridget Deemer, WSU research associate and lead author. "It's contributing right around 80 percent of the total global warming impact of all those gases from reservoirs. It's a pretty important piece of the budget."

While the concentration of methane in the atmosphere is outweighed by carbon dioxide, it is much better at trapping heat beneath the Earth's atmosphere and therefore poses a bigger threat to the climate than CO2 does, pound-for-pound. We know that methane can arise from cows, biomass burning, leaks and reservoirs, but the way it escapes from the latter has so far made its presence hard to quantify.

"Methane is less soluble in water than are the other greenhouse gases included in this study (carbon dioxide and nitrous oxide)," Deemer tells us. "Because of this, a large fraction of methane emission can occur as bubbles. If these bubbles aren't captured by measurements, reservoir methane flux can be underestimated."

The scientists say that these bubbles can make up over 95 percent of methane emissions from some systems, but their study is the first to take them into account. The upshot of this is that reservoirs are emitting 25 percent more methane than we previously thought. But on a more positive note, the researchers tell us that this new knowledge may help us come up with ways to lessen the impact.

"Because reservoirs are human designed and human operated, there may be an opportunity for greenhouse gas mitigation at both the planning and the operation stages," says Deemer. "The results of our study suggest that reservoirs sited in locations downstream of 'nutrient' inputs will produce more methane than those receiving fewer nutrient inputs. Large nutrient inputs to waterways are often associated with human activities like food and energy production. It is also possible that reducing nutrient inputs to existing reservoirs could reduce methane emissions, but this remains to be tested in the field."

The team's research is scheduled to be published in the journal BioScience.

Source: Washington State University

20 comments
VincentWolf
The biggest source of methane and CO2 is politicians.
GlassHalfEmpty
Ban reserviors.
IanRivlin
Yes, I totally agree. To save the planet, we should all stop drinking and die of thirst. It's the only decent thing to do. The Greens should lead the way by setting an example - and be the first to cease drinking.
habakak
OMG! Run for the hills!
piperTom
It really makes you wonder: which is the greater danger, alarmism or actual climate change? Reading this (and many, many other government funded "studies"), I have to fear the alarmists more.
Mark Uzick
Co2 is barely even a greenhouse gas; the only serious greenhouse gas, in terms of abundance and effectiveness, is water vapor! Does this attention to water reservoirs mean their getting closer to admitting the truth?...Nah!
Jeff Goldstein
This is just more evidence that climate change is such new and complex science that anyone who says anything is settled science in the field has no clue what they are talking about. Contrary to what Obama/Kerry and the Democrats say, you can't have government policy deal with this until you know much more.
Science and Econ
Another nonsense article! The claim of "human-induced climate change" is a hoax. This has been an open secret for 20+ years. Water Vapor, the Sun, etc. drive climate; Carbon Dioxide levels FOLLOW after a lag of some centuries.
You really have to aggressively avoid science to NOT know that Anthropogenic Global Warming (AGW) is a hoax. The real question is: How did ANYONE fall for the Carbon Dioxide HOAX?
Man-generated Carbon Dioxide is responsible for roughly 0.0001% of the greenhouse effect - far smaller than the month-to-month variability and far smaller than Man’s ability to measure - so tiny that the sign could be (+) or (-) due to the highly negative feedbacks that permeate all natural systems.
I'm so tired of AGW propaganda!
LordInsidious
I love the attitude that as we learn more about things then everything else must be dismissed as false weather it is relevant or not. The only science failure I see is the in a class room where science and it basis, the scientific method, was taught.
Robert in Vancouver
Looking at a 150 million year chart, CO2 is at the lower end of the scale now. If CO2 drops 15% lower, there won't be enough CO2 to support vegetation growth, and if plants stop growing, all life on earth will die before you can say "inconvenient truth". So it's time to stop the fanatical anti-CO2 propaganda and use all that money and effort to work on things that actually harm and kill us such as diesel exhaust particulate, cancer, malaria, etc.