Posted: 25 Apr 2009 09:56 AM PDT
The news from NOAA, “Greenhouse Gases Continue to Climb Despite Economic Slump,” is that all our dawdling on climate action this decade is having real impact on the atmosphere:
Two of the most important climate change gases increased last year, according to a preliminary analysis for NOAA’s annual greenhouse gas index, which tracks data from 60 sites around the world.
Researchers measured an additional 16.2 billion tons of carbon dioxide (CO2) — a byproduct of fossil fuel burning — and 12.2 million tons of methane in the atmosphere at the end of December 2008. This increase is despite the global economic downturn, with its decrease in a wide range of activities that depend on fossil fuel use.
That meant a 2.1 ppm rise in atmospheric CO2 concentrations to 386 ppm, easily the highest levels homo “sapiens” sapiens have ever seen, which is not news (see “World carbon dioxide levels jump in 2008 to highest in 650,000 — if not 20 million — years“), but should still worry everyone since it continues the nearly 40% higher rate of growth of concentrations this decade compared to last. It also meant a 4.4 part per billion rise in methane concentrations, which definitely is news — and far more worrisome.
Sharply rising methane levels have been implicated in most every major rapid warming spell in Earth’s history, as Nature (subs. req’d, excerpted below) explained in a report last month. The report, on what they called “a ticking time bomb,” warned the “vast stores of methane — a potent greenhouse gas — could be released from frozen deposits on land and under the ocean.”
[Note: The figure above is from the Nature article, but I have rather lamely added the 2009 data point and even more lamely extended the running mean line. I only did this because NOAA doesn't appear to have graphed their latest data -- unlike last year (see "NOAA: Atmospheric Carbon Dioxide, Methane Rise Sharply in 2007").]
NOAA deserves praise for some clarity and bluntness — thank you Dr. Lubchenco, “another scientist who gets climate“:
“Only by reducing our dependence on fossil fuels and increasing energy production from renewable resources will we start to see improvements and begin to lessen the effects of climate change,” said scientist Pieter Tans of NOAA’s Earth System Research Laboratory in Boulder, Colo.
I don’t think that sentence every appeared in a NOAA release during the previous administration (aka the Dark Ages).
“Think of the atmosphere and oceans taking in greenhouse gases as a bathtub filling with more water than the drain can empty, and the drain is very slow,” said Tans. “We need to reduce greenhouse gas emissions to the point where they match levels that can be absorbed by Earth’s ecosystems.”
The useful bathtub analogy strikes again! (see here)
The increases in CO2 and methane during 2008 are slightly less than those measured in 2007, but fall well within the range of yearly fluctuations from natural changes, according to NOAA experts.
The rise in CO2 levels varies from year to year along with plant growth and decay, wildfire activity, and changes in soil conditions. Emerging from that natural variability is a consistent upward trend produced by burning coal, oil, and gas for transportation and industry.
NOAA says we have met the enemy, and he is us.
So why is the methane rising? Here’s my explanation. As a major 2008 study found, Permafrost loss linked to Arctic sea ice loss:
We find that simulated western Arctic land warming trends during rapid sea ice loss are 3.5 times greater than secular 21st century climate-change trends. The accelerated warming signal penetrates up to 1500 km inland….
In other words, the recent trend in sea ice loss is poised to triple Arctic warming, causing large emissions in carbon dioxide and methane from the tundra this century. What is especially worrisome is that 2007 and 2008 provide strong evidence on behalf of this theory:
- NOAA just reported that “methane levels rose in 2008 for the second consecutive year after a 10-year lull.”
- The tundra can emit vast amounts of methane when it defrosts (see Part 1).
- Scientific analysis suggests the rise in 2007 methane levels came from Arctic wetlands (see here).
- And 2007 saw record Arctic ice loss [see "Ice Ice Maybe (not)"] — as did 2008 (see “here)
David Lawrence of the National Center for Atmospheric Research (NCAR) has analyzed permafrost loss this century under various warming scenarios:
[Lawrence told me that using the above figure is "still fine as long as one mentions the caveats that permafrost is probably degrading a bit too rapidly in the original” (see discussion, literature links here).]
Note that the B1 scenario is “stabilizing” at 550 ppm atmospheric concentrations of carbon dioxide, but in fact NCAR’s model doesn’t look at the feedback of the CO2 and methane emissions from the tundra loss, which would drive concentrations far higher! So we must avoid 550 at all cost, since the tundra feedback, coupled with the climate-carbon-cycle feedbacks that the IPCC models, could easily take us to the unmitigated catastrophe of 1000 ppm (see Tundra, Part 2: The point of no return).
We are, of course, on pace to exceed the A2 scenario — U.S. media largely ignores latest warning from climate scientists: “Recent observations confirm … the worst-case IPCC scenario trajectories (or even worse) are being realised” — 1000 ppm.
I’ll end with longer excerpts from the Nature report:
In 2007, scientists scouting the icy waters of the Arctic Ocean began to notice some troubling signs. In about half of their seawater chemistry samples, the concentration of dissolved methane was two to ten times higher than in samples taken during previous years from the same locations. Then, last summer, they observed large rings of gas — sometimes as wide as 30 centimetres in diameter — trapped in ice, as well as methane plumes bubbling to the surface over hundreds of square kilometres of the shallow waters along the Siberian Shelf.
The team, from Russia and other nations, presented their results at the American Geophysical Union’s Fall Meeting in December, where scientists cautiously voiced their concerns that large quantities of methane are becoming destabilized as the planet — and the ocean — heat up. Researchers have long speculated that warming could unleash vast stores of the greenhouse gas from where it lies frozen beneath the sea floor and locked up in Arctic soils. If those deposits were to melt, it would almost certainly trigger abrupt climate change. Methane heats the atmosphere with an efficiency 25 times that of carbon dioxide, and its release could put in motion a positive feedback loop in which warming releases methane, causing further warming, which liberates even more of the gas. Whether that’s already happening is anyone’s guess. Scientists are quick to point out that the Arctic methane plumes could be anomalous or simply part of a longer-term trend. Natalia Shakhova, a biogeochemist at the University of Alaska, Fairbanks, and one of the leaders of the Siberian Shelf study, says, “Two years is nothing in geologic time scales.” James Kennett, an Earth scientist at the University of California, Santa Barbara, agrees and says it is very possible that the Arctic methane releases “just simply weren’t observed before.”
See Arctic Research Center at AGU: The underwater permafrost is thawing and releasing methane.
During the Pleistocene, which lasted from about 1.8 million years ago until 10,000 years ago, ice sheets cloaked much of North America and Eurasia, and animals such as woolly mammoths and mastodons lumbered around on the frozen, icy tundra. This era was brought to an abrupt end by a rapid warming spell that caused widespread glacial melting, raising sea levels by more than a hundred metres and triggering mass extinctions. According to research by Katey Walter and her colleagues, methane bubbling up from the bottoms of Arctic lakes accounted for between 30 and 87 per cent of the rise in atmospheric methane that helped bring an end to the Pleistocene8. These lakes now account for six per cent of global methane emissions. “So we know that they have the potential to become an even bigger source in the future,” says Walter.
More recently, Martin Kennedy and colleagues reported in Nature that a massive release of methane some 635 million years ago might have spelled the end of the last ’snowball Earth’ period, when ice sheets stretched as far as the Equator. According to their analysis, this was a period of abrupt glacial melting and destabilization of methane hydrates. Although there is not widespread agreement about what role methane has played in periods of abrupt climate change in Earth’s history, “When we look at the geologic record, at critical thresholds, methane is implicated in almost all of those occurrences,” says Kennedy.
Bottom line:
“These deposits [of methane] rival fossil fuels in terms of their size. It’s like having a whole additional supply of coal, oil and natural gas out there that we can’t control,” says James White, a geochemist at the University of Colorado, Boulder….
In the meantime, how concerned should we be about the possibility of climate catastrophe resulting from methane? “It’s probably safe to say that we don’t know,” says White. “But if there’s a ticking bomb in the room, you’d like to know the possibility of it going off. The fact that it’s there at all is unnerving.”
Paging Jack Bauer — although this is one ticking-time-bomb scenario where we already know who is behind it and how to stop it.
Related Posts:
Posts
No comments:
Post a Comment