Tropical Cyclones Adding to Global Warming?

Eyewall of Hurricane Ivan.

Usually, when most people see the words global warming and tropical cyclones put together, they think about the influences (or lack of) of global warming on tropical cyclones, and not the other way around.

In this new study from Harvard University, we read about the possible influence of tropical cyclones on climate.

Using 23 years of infrared satellite imagery, global tropical cyclone best-track data, and reanalysis of tropopause temperature, the authors found that tropical cyclones contribute a disproportionate amount of the tropical deep convection that overshoots the troposphere and reaches the stratosphere, according to the ScienceDaily article.

Diagram of the hurricane eyewall.

The authors of the study found that tropical cyclones contribute 7% of deep convection in the tropics, but that 15% of that convection reaches the statosphere.

Based on this information, the research team concluded that tropical cyclones could play a key role in adding water vapor (the most widespread greenhouse gas) to the stratosphere, which has shown to increase surface temperature. This leads them to conclude that there is the possibility of a positive feedback between tropical cyclones and global warming.

If this is in fact true, I would think the influence would be extremely small based on the percentages, especially when you think globally.

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This paper is published in the Geophysical Research Letters.

Is Methane The Cause Of Past Ice Age Global Warming?

By studying gas bubbles frozen in ancient Greenland ice, University of Victoria researchers have dispelled a popular theory that marine gas hydrates caused a significant release of methane gas into the Earth’s atmosphere, triggering a period of global warming at the end of the last ice age.

“Understanding the behaviour of global atmospheric methane is important because it’s the third strongest greenhouse gas after carbon dioxide and water vapour,” says biogeochemist Dr. Michael Whiticar, part of the Canada-U.S. team that conducted the study. “Atmospheric methane concentrations have increased about 250 per cent in the last 250 years, and they continue to rise about one per cent a year.”

Methane in the Earth’s atmosphere is an important greenhouse gas with a global warming potential of 25 over a 100-year period. This means that a methane emission will have 25 times the impact on temperature of a carbon dioxide emission of the same mass over the following 100 years. Methane has a large effect for a brief period (about 10 years), whereas carbon dioxide has a small effect for a long period (over 100 years). Because of this difference in effect and time period, the global warming potential of methane over a 20 year time period is 72.

The Earth’s methane concentration has increased by about 150% since 1750, and it accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases.

The team, which included PhD student Hinrich Schaefer, studied the concentration and carbon isotope fingerprints of the methane in the ice off Pakitsoq, Greenland. The technique enabled researchers to investigate the changes in sources and sinks of atmospheric methane - perhaps analogous to today’s rapid rise in the Pleistocene and Holocene ages.

“Methane is a gas that makes a significant contribution to global warming but has gone largely unnoticed by the public and some policy-makers,” says Schaefer, now pursuing postgraduate studies at Oregon State University. “Its concentration has more than doubled since the industrial revolution, from things like natural gas exploration, landfills and agriculture. We need to know whether rapid increases of methane in the past have triggered global warming or have just been a reaction to it.”

According to Whiticar, the study shows that massive destabilization of methane hydrates along the oceanic shelves and the corresponding release of methane to the atmosphere can’t be responsible for detonating the rise in greenhouse gases 12,000 years ago.

“Our work supports the belief that wetlands and permafrost layers are responsible for the enhanced sources of methane to the atmosphere. This is critical knowledge because again, today, we see rapid retreating of our northern permafrost boundaries due to Arctic warming.”

The findings of the team’s research were featured in an article in the Aug. 25 edition of the international journal Science. Funding for the Canadian aspects of the work was provided by the Canadian Foundation for Climate and Atmospheric Sciences, the Natural Sciences and Engineering Research Council and the Canada Foundation for Innovation, with collaborations with Oregon State University, the University of Colorado, and the Scripps Institution of Oceanography at the University of California at San Diego.

In Search of Missing Atmospheric CO2

NASA is planning to launch a 278 million dollar satellite program next month to measure atmospheric carbon dioxide (CO2) and find out where it goes, according to a Reuters article.

This technology measures light bounced off the planet. Carbon dioxide absorbs light in some frequencies, so the less light detected, the higher the concentration of carbon.

The world's oceans and land absorb much of the atmospheric CO2, but scientists have been unable to figure out where the remaining CO2 goes.

Knowing these answers will help scientists and models better predict the speed and extent of carbon dioxide's impact on the world's climate.

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In a somewhat related story......Scientists are planning on using a souped-up corporate jet (and no, it is not the 50 million dollar Citigroup jet) to determine where and when some of the estimated 30 billion tons of carbon emitted annually by cars, factories, deforestation and other human activities enters the atmosphere.

Roughly half the carbon emitted by humans stays in the atmosphere, with the remainder being absorbed by ocean and earth ecosystems. But scientists don't understand how the system works or how quickly various gases mix.ers the atmosphere, according to the Scientific American article.

The result is that models of this so-called carbon cycle grown wildly divergent as they are projected into the future, with nearly 100 percent uncertainty by 2050, according to Britton Stephens, a scientist with the National Center for Atmospheric Research and one of the project's principal investigators.

The project will fill key gaps in our understanding of how carbon cycles through the atmosphere and among the earth, air and oceans.

The new map will also provide a baseline against which efforts worldwide to curb carbon emissions can be judged. Need for such a benchmark has gained urgency, scientists and policymakers say, as the world moves toward regional, national and international agreements to limit greenhouse gases.