Wednesday, March 23, 2011

Natural gas development could worsen global warming.


A natural gas drilling rig
in the Marcellus shale region.
Last week, three Cornell University researchers, Robert Howarth, Renee Santoro, and Tony Ingraffea, gave a seminar about natural gas development and its potential contribution to climate change.  Overall, they found that the natural gas industry's carbon footprint plus methane footprint was greater than that of the coal and oil based industries, thus increasing the likelihood that global warming will exacerbated by further implementation of natural gas production.  Their findings will be published in the upcoming April edition of Climatic Change Letters, as an addendum to the main journal, Climate Change.

Natural gas has long been touted as a "cleaner" fuel than oil, simply because less carbon dioxide is released into the atmosphere upon burning.  However, the principal component of natural gas is methane, which is a much more potent global warming gas than carbon dioxide.  During natural gas production a small percentage of methane is released into the atmosphere, either intentionally through venting, or inadvertently through leaks in the pipeline.  While methane does not last nearly as long in the atmosphere as carbon dioxide, over the short term (20 years as opposed to 100 years), its global warming potential is estimated to be 72 times greater than that of carbon dioxide.

The researchers looked at the overall life-cycle of natural gas production and compared methane emissions at each stage of production using industry reported data.  They also compared emissions between shale gas production and conventional gas.  They found that 3.6% to 7.9% of methane from shale-gas production escaped into the atmosphere during venting and leaks, almost two times greater than the emissions from conventional gas.  These increased emissions in shale-gas production occured during the hydraulic fracturing of a well and during the drill out following fracturing.  Their findings are in conjunction with a November 2010 Environmental Protection Agency report that found that emissions, particularly for shale gas, are larger than previously believed.

As many countries consider the adoption of shale-gas production as an alternative to oil-based energy sources, more research, similar to this study, will become gravely important to asess the true consequences to climate change.

Sharinne Sukhnanand

These briefs are part of a weekly series of updates to the publication: Climate Change: Past, Present, and Future.  The entire series can be found here.

Friday, March 11, 2011

Get out your tissue box: researchers find that global warming extends the pollen season in northern latitudes.


Credit: Sue Sweeney/ Wikimedia Commons
Researchers studying ragweed (Ambrosia spp.), one of the worst allergy-causing plants, particularly for the summer and fall season, have found that its pollen season has been extended, due to warming temperatures in the upper latitudes.  In northern states, such as Wisconsin and Minnesota, the ragweed pollen season has been extended by roughly two weeks (13-16 days).  Further north, in areas of Canada, such as Winnipeg and Saskatoon, the ragweed season has been stretched by almost one month (25-27 days)!

Their findings are consistent with the United Nations' Intergovernmental Panel on Climate Change (IPCC) assessment that current and projected increases in global warming are not uniform and depend, rather, on latitude and elevation.  The researchers looked at pollen counts and weather data from 10 locations across the North American continent, from as far south as Georgetown, Teaxs to as far north as Saskatoon, Canada over a 15 year period (1995-2009).  As latitude increased, they observed an increase in the usual length of the growing season (increase in the frost-free period), as well an a change in the number of days to first frost.  Upper latitudes are warming faster than mid-latitudes and the researchers found that changes in the length of the ragweed pollen season were in proportion to these warming differences.

The impact of study goes beyond a couple of sniffles and sneezes.  The authors cite that ragweed may cause more seasonal allergic reactions than all other plants combined.  And for those who suffer from asthma, allergies can oftentimes trigger asthma or make it worse.   With a now longer pollen season and increased pollen counts, the number of people affected by allergic reactions to ragweed could increase dramatically.

Sharinne Sukhnanand

These briefs are part of a weekly series of updates to the publication: Climate Change: Past, Present, and Future.  The entire series can be found here.

Wednesday, March 2, 2011

How dry can the Earth's climate get? Researchers discover an ancient mega-drought.


Credit: Tomas Castelazo, Wikimedia Commons
Scientists have discovered one of the most intense and far-reaching droughts in the history of early modern humans, according to a new study recently published in Science magazine.  The drought, also referred to as the H1 Megadrought, affected large areas of Africa and Southern Asia, shrinking lakes, rivers, and vital freshwater supplies.  Lake Victoria, currently the world's largest tropical lake, dried up completely, as did Lake Tana, in Ethiopia.  Both lakes are primary water sources for the Nile River, suggesting that the mega-drought had severe ecological impacts on ecosystems and communities from East Africa to the Mediterranean coast.  

In addition, the study showed that the regular monsoon rains for these regions didn't just migrate south during the drought, as previously thought.  The rains weakened significantly as well, thus revealing that the mega-drought had a much greater geographical impact and was more catastrophic than previously believed.

Interestingly, an analysis of sediment cores revealed that the mega-drought took place roughly 16,000 to 17,000 years ago, which coincided with another major climate change event: the peak of the Heinrich Stadial 1, a massive surge of icebergs and meltwater into the North Atlantic at the end of the last ice age.  While it is still unknown whether the massive ice melt contributed or even caused the mega-drought, the study discusses possible ways that the Heinrich event may have influenced atmospheric and rainfall systems in favor of a drought.

The authors mention that the mechanisms that drive rainfall systems in the African-Asian region, which affect more than half of all humanity, are poorly understood and difficult to model. However, as the Arctic continues to melt at an unprecedented rate, the study raises valid questions about whether the current ice melt could, in theory, contribute to a similar drought.   

Sharinne Sukhnanand

These briefs are part of a weekly series of updates to the publication: Climate Change: Past, Present, and Future.  The entire series can be found here.