September 26, 2012

More Evidence Against a Methane Time Bomb

Over at Watts Up With That, Anthony Watts has highlighted a recent press release from the German Helmholtz Center for Ocean Research Kiel announcing the preliminary findings from an expedition this summer to the Greenland Sea (off the coast of Spitzbergen). The expedition on the German research vessel the Maria S. Merian was aimed at investigating the release of methane from the seafloor—one of the many potential apocalyptic positive feedback pathways which lead from an initial warming instigated by anthropogenic greenhouse gas emissions. Watts drew attention to the press release because the researchers were reporting that contrary to expectations, the release of methane from the seabed was found not to be a recent phenomenon (i.e., a result of global warming), but instead that many of the gas outlets had been active for long before local ocean temperatures have been rising.

According to the press release:

Above all the fear that the gas emanation is a consequence of the current rising sea temperature does not seem to apply.

And also, although the full details from the expedition’s data collections will not be known for several months, the scientists suggested that

[T]he observed gas emanations are probably not caused by human influence.

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June 7, 2012

Asian Air Pollution Warms U.S. More Than U.S. Greenhouse Gas Emissions?

There is a just-published study that provides evidence that air pollution emanating from Asia will warm the U.S. as much as or even more than all U.S. greenhouse gas (GHG) emissions.

Such a result effectively renders all EPA and other efforts at mitigating climate change in the U.S. by limiting homegrown GHG emissions mute.

Over at the web site Master Resource, there is a detailed discussion into how the warming effect from Asian air pollution compares with the warming effect of U.S. CO2 emissions. [Spoiler Alert] It turns out, that the two are pretty much on par with one another—which leads to the uncomfortable question: If the future temperature rise in the U.S. is subject to the whims of Asian environmental and energy policy, then what sense does it make for Americans to have their energy choices regulated by efforts aimed at mitigating future temperature increases across the US—efforts which may have less of an impact on temperatures than the policies enacted across Asia?

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December 16, 2011

“Methane Time Bomb in Arctic Seas – Apocalypse Not”

Our headline is taken from New York Times blogger Andy Revkin’s recent DotEarth post covering the results of a new paper which investigates the relationship between higher temperatures in recent decades and methane release from the Arctic seabed off the Siberian coast. As you can probably tell from the headline, the research team, led by Igor Dmitrenko, did not find that global warming, current and future, was going to have much of a dramatic impact on the release of methane from the Arctic seas. This is a fairly significant finding because methane—which has about 20 times the impact on the greenhouse effect that carbon dioxide does on a molecule by molecule basis—has the potential to act as a large amplifier (positive feedback) to a warming climate. Consequently the specter of a large Arctic methane release plays a prominent role in many of the more alarming future climate change storylines.

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August 5, 2011

The Lack of Recent Warming and the State of Peer Review

Over at the Cato Institute website, WCR’s Patrick Michaels has another one of his informative Current Wisdom pieces, a place where he “reviews interesting items on global warming in the scientific literature that may not have received the media attention that they deserved, or have been misinterpreted in the popular press.” The topic this time around is the recent paper in the Proceedings of the National Academy of Sciences by Robert Kaufmann and colleagues in which they conclude that one of the primary reasons that the earth has not warmed up as advertised during the past 10 -15 years is that rapidly growing sulfur emissions from China (as a result of their increased usage of coal for power generation) have acted to offset a significant proportion of the greenhouse warming.

Pat explains why this hypothesis is, well, simply wrong.

Instead, natural variability is the primary reason, along with the possibility that the climate sensitivity (i.e., how much warming will occur as atmospheric greenhouse gas levels double) is on the low side of IPCC estimates (which range from 2.0°C – 4.5°C).

Pat also details the trials and tribulations that we encountered when trying to publish this finding several years ago.

Check out all the sordid details in the article The Current Wisdom: The Lack of Recent Warming and the State of Peer Review.




April 29, 2011

Shale Gas: A Climate Friendly Fossil Fuel?

A few weeks back, in our article Biggest Drop in U.S. Greenhouse Gas Emissions, we promised to take a look at the implications of a new study that calculated the impact on the earth’s greenhouse effect from the extraction and use of natural gas produced from deep underground shale beds (through a process known as hydraulic fracturing, or “fracking”). The study was conducted by a research team from Cornell University led by Dr. Robert Howarth, and its conclusions were quite surprising:

“Compared to coal, the [greenhouse gas] footprint of shale gas is at least 20% greater and perhaps more than twice as great on the 20-year horizon and is comparable when compared over 100 years.”

The reason that this is surprising (and has a lot of people talking) is that natural gas has long been considered the most “climate friendly” of all the fossil fuels and a potential “bridge” to a low carbon future. The Howarth et al. study now threatens natural gas’s most favored status (at least among climate change-fearing types).

Over at the free market energy blog Master Resource, WCR’s Chip Knappenberger takes a look at the Howarth et al. study, as well as its many criticisms.

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April 14, 2011

Biggest Drop in U.S. Greenhouse Gas Emissions

In 2009, greenhouse gas emissions in the U.S. experienced their biggest drop since the U.S. Energy Information Administration began tracking them during the 1990-2009 timeframe.

The EIA’s latest numbers on greenhouse gas emissions can be found in their just released report “Emissions of Greenhouse Gases in the United States 2009.”

The EIA starts out with this summary:

Total U.S. anthropogenic (human-caused) greenhouse gas emissions in 2009 were 5.8 percent below the 2008 total. The decline in total emissions—from 6,983 million metric tons carbon dioxide equivalent (MMTCO2e) in 2008 to 6,576 MMTCO2e in 2009—was the largest since emissions have been tracked over the 1990-2009 time frame. It was largely the result of a 419-MMTCO2e drop in carbon dioxide (CO2) emissions (7.1 percent).

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November 10, 2009

Airborne Fraction of Human CO2 Emissions Constant over Time

A couple of months back, there was a discussion taking place over at Joe Romm’s ClimateProgress blog concerning a report that the earth’s ability to take-up atmospheric carbon dioxide was declining. A declining CO2 sink, of course, meant that things climatological were going to be even worse than expected, because a growing proportion of anthropogenic CO2 emissions were going to remain in the atmosphere, thus pushing the rise of CO2 concentrations and the degree of climate change higher.

At the time, an alert reader pointed out to Joe Romm that there was in fact, no indication from data and observations that a larger percentage of human CO2 emissions were ending up in the atmosphere. In fact, the data showed that the fraction of CO2 emitted into the atmospheric by human activities has remained constant for the past 40 years.

This fact runs directly counter to the idea that the earth’s natural CO2 sinks are weakening—instead it indicates that natural sinks have been expanding as anthropogenic CO2 emissions have increased. After all, in order to keep the airborne fraction of CO2 emissions constant over time, increasing anthropogenic CO2 emissions must be countered by an increasing CO2 sink.

Joe Romm was a bit dismissive (to say the least) of this line of argument.

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October 8, 2009

The Ups and Downs of Methane

One of the indisputable facts in the field of global climate change is that the atmospheric build-up of methane (CH4) has been, over the past few decades, occurring much more slowly than all predictions as to its behavior (Figure 1). Since methane is a particularly potent greenhouse gas (thought to have about 25 times the warming power of CO2), emissions scenarios which fail to track methane will struggle to well-replicate the total climate forcing, likely erring on the high side—and feeding too much forcing into climate models leads to too much global warming coming out of them.


Figure 1. Atmospheric methane concentrations, 1985-2008, with the IPCC methane projections overlaid (adapted from: Dlugokencky et al., 2009)

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June 16, 2009

Does EPA Have the Wrong Gas?

Over at MasterResource.org is an article looking at EPA’s Proposed Endangerment and Cause or Contribute Findings for Greenhouse Gases Under Sections 202(a) of the Clean Air Act, and wonders whether or not the EPA has set its sight on the correct gas. The EPA’s focus seems to be on carbon dioxide, but a very strong case can be made that the net effect of increasing atmospheric carbon dioxide concentrations may not be so bad (in fact, it may be quite good). So instead of risking the possibility that if they consider the climate impacts of CO2 alone they very well may not be able to build a case for an “endangerment to public health or welfare,” the EPA has lumped CO2 together with five other greenhouse gases thus watering down the positive aspects of CO2 with the potential negative ones from the other gases.

The MasterResource piece argues that to make a fair assessment of its effect on climate, CO2 should be unlumped and considered on its own.




June 10, 2009

Sulfates and Global Warming

Usually when we think of global warming, we are led to believe that it is caused primarily by increasing greenhouse gases. After all, that is what all the fuss is about in Washington DC these days. But is that entirely true?

After all there are lots of other things going on all the while. For instance, to what degree has the global temperature record in recent decades been influenced by the variability in aerosol emissions?

This question has been the subject of a series of articles in recent years by Martin Wild and colleagues which look at the impacts of (primarily sulfate) aerosols on the earth’s climate. They typically conclude that sulfate aerosols play a larger role in multi-decadal climate fluctuations than the climate models generally give them credit for. And that models’ inability to properly handle the climate aspects of aerosols “may hamper the predictive skills of these models to project near future climate evolution.”

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