IWETHEY v. 0.3.0 | TODO
1,095 registered users | 1 active user | 1 LpH | Statistics
Login | Create New User
IWETHEY Banner

Welcome to IWETHEY!

New hydro-electric dams can actually emit more greenhouse gases than coal-fired powerplants.
always look out for number one and don't step in number two
New Meh.
https://www.internationalrivers.org/resources/greenhouse-gas-emissions-from-dams-faq-4064 (from 2007):

Q: What is the contribution of dams to global warming?
According to the most detailed estimate available, done by Ivan Lima and colleagues from Brazil's National Institute for Space Research (INPE), the world's large dams emit 104 million metric tonnes of methane annually from reservoir surfaces, turbines, spillways and rivers downstream (1). This implies that dam methane emissions are responsible for at least 4% of the total warming impact of human activities. No one has yet calculated the total climate impact of dams, which would include releases of carbon dioxide and nitrous oxide.

Q: How do emissions from dams compare to those from other sources?
According to the estimates of the INPE researchers, dams are the largest single anthropogenic source of methane, being responsible for 23% of all methane emissions due to human activities. Methane is a much more potent heat-trapping gas than carbon dioxide, although it does not last as long in the atmosphere.

The most recent assessment of the Intergovernmental Panel on Climate Change states that methane has a warming impact 72 times higher than carbon dioxide if measured over 20 years, and 25 times higher measured over 100 years. Using these IPCC "global warming potential" (GWP) estimates means that one year's methane emissions from large dams, as estimated by Lima, have a global warming impact over 100 years equal to that of 2.6 billion tonnes of carbon dioxide. (Under the Kyoto Protocol, countries estimate their total warming impact using the 100 year GWPs). Over 20 years, the warming impact of annual large dam methane emissions is equivalent to 7.5 billion tonnes of carbon dioxide. By comparison:

Global CO2 emissions from fossil fuel burning (2004): 26.6 billion tonnes (2)
US CO2 emissions from fossil fuel burning (2005): 6 billion tonnes (3)
EU-15 emissions from fossil fuel burning (2003): 3.3 billion tonnes (4)
Global CO2 emissions from coal (2003): 9.6 billion tonnes (5)
US CO2 emissions from coal (2005): 2.1 billion tonnes (3)
US CO2 emissions from road transport (2005): 1.7 billion tonnes (3)
Global CO2 emissions from aviation (2002): 0.5 billion tonnes (6)


There's a big difference between fossil fuel releases of CO2 and methane, and surface CO2 and methane that is part of the natural, quick, carbon cycle. The stuff from dams (while important) isn't from fossil fuels (except maybe in the concrete manufacturing, etc.).

Dams aren't a big source of GHG, but they do need to be considered.


Cheers,
Scott.
New newer article
always look out for number one and don't step in number two
New That was a click-bait headline. ;-)
Actual real numbers are here:



3. Anthropogenic Sources

3.1 Rice Cultivation

What we know:

Rice production may account for 10% (~30-60 Tg) of the total annual methane emission.
Since 1980, rice production has risen by over 40% through the combined effects of increased harvest areas and higher yields.
Over 90% of the harvested area is confined to Asia.


The university press release that your link cites says:

VANCOUVER, Wash. – Washington State University researchers say the world’s reservoirs are an underappreciated source of greenhouse gases, producing the equivalent of roughly 1 gigaton of carbon dioxide a year, or 1.3 percent of all greenhouse gases produced by humans.


It's an important source, but it's not what should be attacked first. Coal, oil, gas production, rice cultivation, etc., are much, much more important sources.

Cheers,
Scott.
New what do you have against rice? Stop growing rice what are we going to eat?
always look out for number one and don't step in number two
New We can make better rice that doesn't make as much methane.
http://phys.org/news/2015-07-scientists-low-methane-rice.html

Scientists said Wednesday they had created a rice variety with starchier grains that emits less methane, a step towards the twin goals of feeding more people and curbing global warming.

The cultivation of rice, a staple starch for billions of people, is also mankind's major emitter of methane, a potent climate-altering gas.

Methane lives for a shorter time in the atmosphere than carbon dioxide (CO2), the most abundant greenhouse gas, but traps far more heat radiated from Earth's surface.

Every year, rice paddies pump out 25 to 100 million tonnes of methane—the second-most important greenhouse gas at about 16 percent.

This means a high risk for the planet as rice cultivation expands to feed a growing population, said the paper, published in the journal Nature.

"There is an urgent need to establish sustainable technologies for increasing rice production while reducing methane fluxes from rice paddies," wrote the team led by Chuanxin Sun of the Swedish University of Agricultural Sciences.

[...]


Cheers,
Scott.
New If . . .
. . it doesn't have good flavor, texture and cooking properties - they won't be able to sell it. It also has to be productive using rather primitive agricultural methods. Scientists often forget about all this stuff.
     hydro-electric dams can actually emit more greenhouse gases than coal-fired powerplants. - (boxley) - (6)
         Meh. - (Another Scott) - (5)
             newer article - (boxley) - (4)
                 That was a click-bait headline. ;-) - (Another Scott) - (3)
                     what do you have against rice? Stop growing rice what are we going to eat? -NT - (boxley) - (2)
                         We can make better rice that doesn't make as much methane. - (Another Scott) - (1)
                             If . . . - (Andrew Grygus)

This is all frightfully unimportant, but since when has that been a reason not to post?
59 ms