Climate Clippings - August 23

23 August 2010

Human activity obliterates natural carbon cycle in Brazos River

 We crossed the wild Pecos

We forded the Nueces

We swum the Guadalupe

And we followed the Brazos...

Lyle Lovett gave the song new wings, but cowboys for generations have been lamenting lost love down by the "quick sandy" Brazos River.

Now a team of Texas geochemists have reported that damming and other human activities have obliterated something else: the natural carbon dioxide cycle in the state's longest river.

The study, published in the journal Biogeochemistry, is the first to document such overwhelming influence of human activity on carbon dioxide in a major river, according to Rice University.

Earth's rivers are thought to absorb and give off about one gigaton of carbon annually - a fraction of the 8.5 gigatons of carbon dioxide humans add to the atmosphere annually through the burning of fossil fuels, but a significant factor in any effort to describe how the atmosphere and biosphere systems exchange carbon dioxide.

Plants take up carbon dioxide from the air via photosynthesis and store it in leaves and stems. Some of that carbon gets buried in soil and locked away for hundreds or thousands of years. But much is also washed into rivers, where rapid decomposition can quickly return it to the atmosphere, the university reported.

Understanding that cycle is essential, scientists note, if policy makers are to plan effective carbon sequestration measures.

The Texas geochemists expected the Brazos' upper reaches, where the river runs over ancient limestone, to show extremely slow carbon cycling. Further downstream, where there's no limestone and the river runs through a humid, sub-tropical environment, they expected a quicker cycle common in tropical rivers.

Lab results showed the exact opposite.

"The carbon dioxide chemistry in the Brazos is flipped," said study co-author Bill Hockaday, assistant professor of geology at Baylor University in Waco, Texas. "In the upper part of the river, damming has changed the dynamics so much that if there ever was any carbon dioxide coming into the river form the limestone it's been cut off."

"With the damming, the carbon in the upper reaches appears to be rapidly cycling between the air the water due largely to algal photosynthesis."

The findings, added co-author Caroline Masiello, assistant professor of Earth Science at Rice, suggests scientists have some more work in front of them before they can make global assumptions about the role of rivers in the carbon cycle.

"We may need to read many more of these stories before we can understand the bigger, global saga of riverine carbon cycling," she said.

Maybe, instead of lamenting the ladies, cowboys need to croon about carbon:

Now the girls of Little River

They're plump and they're pretty

The Sabine and the Sulphur

Hold beauties a'many

The banks of the Neches

There are girls by the score

But down by the Brazos

I'll wander no more.

Uncle Sam pumps up weatherization efforts 

U.S. Energy Secretary Steven Chu last week awarded $120 million to approximately 120 organizations across the country to drive innovation under the Department of Energy's weatherization assistance program. The investments are meant to encourage the expansion of successful weatherization efforts and support new pilot projects demonstrating new technologies as well as innovative  delivery and financial models.

The program, according to the department, is now weatherizing homes at its optimal run rate - about 25,000 homes per month. In June the program hit a milestone: 31,600 homes weatherized with Recovery Act stimulus funding, the most ever in a month.

Grantees receiving weatherization cash span 27 states and include everything from solar heating systems to small-scale wind to insulation technology to high-efficiency boilers. 

Other winners are fairly untraditional for the department, and include financers, private companies, universities and entities like Habitat for Humanity and YouthBuild USA.

More information and a full list of award selections can be found here on the Department of Energy's Web site.

Disagreeing over how to agree

Why do we disagree about climate change? It's an audacious question, to say the least, writes William Anderegg, biology professor at Stanford University. Yet two new books - James Hoggan's Climate Cover-up and Mike Hulme's Why We Disagree About Climate Change attempt to tackle it.

Both authors, he notes, assess the various - and persistent - barriers and offer up suggestions on how to overcome them. Hoggan ends with a list of ways citizens can take action ("First and foremost, you must inform yourself"). Hulme ends on a gloomier note, concluding we disagree about climate change because we think in ways that are simply and insurmountably different.

Anderegg, writing in the journal Climatic Change, suggests climate scientists and academics need to be better participants in a discourse that extends beyond both science and change. An informed media "serves as a crucial link" between the Ivory Tower and the public, he wrote. "This underscores the need to maintain science and environment reporters as those trained to discern the experts, even as much of the mainstream media is undergoing a transition."

Scholars, Anderegg said, will continue to push into and illuminate the shadow falling across gaps in the scientific record. 

"We must take care that the light reaches the public as well," he said. 

Compiled by Douglas Fischer. Photograph of the Brazos River courtesy Carol Von Canon/flickr. Photograph of worker weatherizing window courtesy Rick Reinhard/Bread for the World.

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