Emissions of Key Greenhouse Gas Stabilize

brian0918 writes "Multiple news sites are reporting that levels of the second most important greenhouse gas, methane, have stabilized". From Scientific American: "During the two decades of measurements, methane underwent double-digit growth as a constituent of our atmosphere, rising from 1,520 parts per billion by volume (ppbv) in 1978 to 1,767 ppbv in 1998. But the most recent measurements have revealed that methane levels are barely rising anymore — and it is unclear why." From NewScientist: "Although this is good news, it does not mean that methane levels will not rise again, and that carbon dioxide remains the 800-pound gorilla of climate change."

Obligatory

[inviolet]

I'll bet global methane emissions can be shown to track the gross sales of Taco Bell.

Hmmmm... their stock has climbed steadily since August [nasdaq.com]. Perhaps the methane readings are due to their recent switch to Canola oil [marketwatch.com].

That's not as much help as you might think.

[sbaker]

The thing is that it takes lots of years for the effect of gas ratio changes at sea level to propagate up into the upper atmosphere.

From the vague article, these appear to be sea-level measurements - so the density of methane in the upper atmosphere (where it actually matters) will continue to grow for maybe 10 years before it starts to level off.

We are seeing the effects of methane growth rates in the 1980's and 1990's...it'll get worse before it gets better.

Re:Arctic

[DigitalRaptor]

I don't know enough about which ice is over the ocean and which is over land, but much of it is over land.

Much of that land is comprised of old peat bogs and other partially decomposed plant life.

As it is exposed and thaws it releases huge amounts of methane. This has already been observed and written about at length [google.com].

IIRC it's one of the greatest potential contributors to the "tipping point [google.com]".

Re:Arctic

[ukemike]

The grandparent poster was not talking about the floating ice on the Arctic Ocean. He was talking about the permafrost in places like Alaska, Canada, and Siberia.

It is suprising that methane has stabilized. There was a paper published this summer stating that melting permafrost was releasing methane at a much higher rate than expected. This would mean that some other source of methane would have to be slowing. If this is true it is good news indeed. Methane is a far more potent greenhouse gas than CO2.

Oh and the previous poster who made the condescending comment about the "doom and gloom" crowd... I am someone whom you would probably lump into that crowd. Notice how I said that this is good news? I don't think many people WANT catastrophic global climate change but people are concerned about the very real possibility.

I believe that we can take action now that can minimize the effects of climate change. A fairly recent ban on CFCs has resulted in an average reduction in the size of the antarctic ozone hole (though it was very big this summer.) The very cool thing about seizing the initiative on this front is that if done right we can stimulate new manufacturing (solar) in the US, stimulate construction, reduce our dependence on dwindling oil supplies, AND "save the world." Or we can sit on our hands and let the opportunity pass.

CO2

[bwy]

and that carbon dioxide remains the 800-pound gorilla of climate change.

Actually, carbon dioxide is a small player. Water is responsible for at least 90% of the Earth's greenhouse effect. It is amazing to me how everyone is so eager to jump on a single bandwagon when it comes to global warming. Anyone who offers contradictory information is immediately dubbed as an "oil company lover" or a "right-wing anti-environmentalist." The first unfortunate truth is that science on both sides is being funded by people with particular interests. Oil companies and industrialists would love for global warming NOT to exist just as much as many anti-corporate liberals and environmental extremists would love for it TO exist.

The second unfortunate truth is that we know very little about the Earth's climate system. It is a complex subject where everything is interdependent on everything else. We need to invest more money into figuring out how it all works and we need to figure out how to get the money to those scientists in such a way that they aren't pressured to produce results that imply specific conclusions.

Do you really expect that the left are sincere in their motives and that they really want to "make the earth a better place?" Hint- the answer is the same as whether you think the right's sincere motive is to "keep the country safe." Most politicians are the same breed. Some will try to convince you that invading Iraq is necessary to protect America and some will try to convince you that new laws are required to prevent global warming and save the environment. Neither side consistently demonstrates the ability to think rationally or objectively which is in fact the only moral way to govern.

Re:Arctic

[alexhard]

Let me guess....you just pulled that out of your ass didn't you?

Let me reference nasa.gov:

"While recent studies have shown that on the whole Arctic sea ice has decreased since the late 1970s, satellite records of sea ice around Antarctica reveal an overall increase in the southern hemisphere ice over the same period."

Get your stories straight or don't post..misinformation doesn't benefit anyone

Re:Arctic

[alexhard]

damn, forgot to link..
http://www.gsfc.nasa.gov/topstory/20020820 southseaice.html

Re:CO2

[toolazytothink]

But in fact, human behaviour does not seem to be changing water vapour concentrations in the atmosphere, while as many many scientists have observed, rising concentrations of CO2 (which seem to be linked to rising levels of development, and energy production and use) are proportional to temperature increases. Water is a much more complicated greenhouse gas because it goes into the atmosphere easily, but it also comes out easily. CO2, on the other hand does not leave the atmosphere easily, and it is having a measurable effect on our climate.

Re:I wonder if this has to do with BSE

[Qzukk]

They're not a major source of methane in the atmosphere OR their crap puts off a ton of methane and we should use it as fuel?

Or their crap has no methane and yet can still be used for fuel (your dichotomy is false).

Anyway, http://www.ciesin.org/TG/AG/liverear.html [ciesin.org] claims that livestock causes 15 of all organic-sourced methane "emissions". Mostly due to fermentation in their stomachs, mostly from low quality feed.

Re:Water Vapor?

[timmarhy]

"First of all the sun remains constant." completely wrong. the sun is NOT CONSTANT. it's ouput varies wildly with solar flares and obviously with the seasons and other solar cycles. "Secondly the evaporation from shallow channels would be much higher then deep colder bodies of water like lakes, rivers or the ocean." AGAIN you couldn't be more wrong. evaporation has nothing to with with depth, and everything to do with SURFACE AREA, of which the ocean clearly dwarfs our irrigation.

Re:20yrs is not a geological timeframe

[PoconoPCDoctor]

I am 54 years old. 44 years ago, I remeber walking home from midnight mass in a blizzard. This was in NY City, and garbage trucks had to pile snow and the end of the streets since there was no where to plow it all. We had snow mountains for a month or so. All of this is anecdotal, and certainly not a "geological" time period.

And yet, I have noticed changes which seem to be born out by hard data that something is happening over a period of 29 years, namely that in certain key areas, such as Alaska in the western hemisphere [noaa.gov], things seem to be warming significantly.

While I don't think anyone here is saying it's still okay to buy a Hummer because CO2 cannot be proven as yet to increase global warming, I think we need to take a really hard look at what we can do planetwide to decrease CO2 emissions at the very least.

Other comments in this thread sarcastically decry the "religion" of global warming. Let's see, I drive a Prius, have replaced all light bulbs in my house with low energy flourescents, and hope to be trained in the Climate Project's slide show that was the basis for "An Inconvenient Truth." [amazon.com] Give me that old time religion...

Re:CO2 does leave the atmosphere easily

[ppanon]

Note: Mankind's activities have clearly increased the amount of H2O in the atmosphere since we divert entire rivers via irrigation.

Last I heard, the oceans covered 2/3rd of the surface of the Earth. It should be pretty clear that, in contrast, evaporation through irrigation on arable land (a fraction of the remaining 1/3) will be a drop in the bucket.

The same can't be said for the production of CO2 from combustion of fossil fuels versus organic processes. And I have never seen spontaneous precipitation of liquid or frozen CO2, but I have seen a lot of rain and snow when humidity levels get high enough. It's pretty clear to me that there are non-biological processes for the regulation of water-vapour content in the atmosphere that don't have an equivalent for CO2. It seems therefore plausible to me that CO2 would have a higher risk of continuing increase than water vapour.

And that is also incorrect

[WindBourne]

While the bulk of the arctic ice is in the ocean, Greenland and the tundras (candian, Russian, American) have huge volumes of ice. There will be issue if all of this ice melts. The greenland glaciers will raise the ocean some none trivial amount. And the tundra ice melt is more important for the sun that it reflects. If that stops, the perma-frost is defrosted AND large amounts of CO2 AND CH4 (methane) will be released.

Re:Water Vapor?

[MyNymWasTaken]

Recent Greenhouse Gas Concentrations [ornl.gov]
The atmospheric lifetime of carbon dioxide is difficult to define because it is exchanged with reservoirs having a wide range of turnover times; IPCC 2001, (page 38 [grida.no]) gives a range of 5-200 years.

The lifetime of excess atmospheric carbon dioxide [agu.org] (Global Biogeochemical Cycles - American Geophysical Union)
If one assumes a terrestrial biosphere with a fertilization flux, then our best estimate is that the single half-life for excess CO2 lies within the range of 19 to 49 years, with a reasonable average being 31 years. If we assume only regrowth, then the average value for the single half-life for excess CO2 increases to 72 years, and if we remove the terrestrial component completely, then it increases further to 92 years.

Re:Water Vapor?

[OriginalArlen]

I have always wondered how much we affect the climate through irrigated fields and a host of other means of adding water vapor to the atmosphere.

Why not [realclimate.org] find out [realclimate.org]? :)

Enjoy :)

Re:Water Vapor?

[Pentagram]

Volcanos and oceans are the major contributers to greenhouse gases. When you add up the numbers, we contribute less than half a percent. But you won't here that from the alarmist crowd.

That's because it's complete bollocks. You have it backwards: volcanoes produce a tiny fraction of the greenhouse gases humans cause to be emitted. Feel free to try to find a source for your "facts".