Posts tagged with NATURE GEOSCIENCE

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Complications of Hacking the Planet

Laborers in Suchate Garh, India, near the border with Pakistan, planting rice seedlings.European Pressphoto AgencyLaborers in Suchate Garh, India, near the border with Pakistan, planting rice seedlings.
Green: Science

As scientists, with some reluctance, begin to study the idea of “geoengineering” the planet to slow or halt global warming, they are finding that any such program would quite likely have a complex array of effects, not all of them to humanity’s benefit.

In a paper released on Sunday by the journal Nature Climate Change, four California researchers used computer analysis to test the idea of managing incoming sunlight and predicted what that would do to crop yields. As an example of the strategies that might be employed, some sunlight could be deflected away from the earth by using planes or rockets to scatter sulfur compounds into the upper atmosphere on a routine basis, mimicking the effect of big volcanic eruptions. It is a potential response to global warming so cheap that it fascinates even some groups that have tried to block action on reining in carbon dioxide emissions.

Fears have long been expressed, however, that while a strategy like this might slow the overall warming, it could wreak havoc on global food security by altering rainfall patterns and other aspects of climate. Particular concern centers on the effects that such a strategy might have on the Asian monsoon, the source of water for crops that feed billions of people. The monsoon is driven by heating over land from strong sunshine in the summertime.

The new work, led by Julia Pongrantz of the Carnegie Institution for Science, found the opposite of these longstanding fears: managing incoming sunlight would probably benefit crop yields over all. The reason is that the technique would limit some of the damaging climate changes that are expected to hurt yields, like excessive temperatures in the growing season, but would nonetheless allow plants to benefit from higher levels of carbon dioxide in the atmosphere. The latter are rising, of course, because of fossil-fuel burning and are the main reason for global warming in the first place, but extra carbon dioxide does act as a kind of plant fertilizer.
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A Carbon Culprit: Rivers and Streams

The Mississippi, viewed from south of Brainerd, Minn.Associated PressThe Mississippi, viewed from south of Brainerd, Minn.
Green: Science

The amount of carbon dioxide being released from streams, rivers and lakes is probably being undercounted by scientists modeling the earth’s carbon budget, a new study suggests.

The carbon dioxide emitted by inland waterways has only recently been included in assessments of global emissions over all. To date, it has mostly been measured in the form of carbon transfer from freshwater bodies to oceans.

But after looking at water chemistry data from 4,000 inland waterways, the study’s authors, from the Yale School of Forestry and Environmental Studies, found streams and rivers in the United States alone release almost 100 million metric tons of carbon dioxide each year.

This release “is equal to a car burning 40 billion gallons of gasoline, enough to drive back and forth to the moon 3.4 million times,” said the study, published in the journal Nature Geoscience.
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Climate Change Igniting Deep Peatland Fires, Study Says

A boreal forest fire in Canada.Natural Resources Canada-Canadian Forest Service A boreal forest fire burns deep into the soil, releasing carbon dioxide.
Green: Science

Climate change is causing Alaskan wildfires to burn longer and more deeply, liberating vast stores of soil-based carbon dioxide that will further accelerate warming, a new study has found.

Prior studies have shown that the extent of wildfires in Alaska increased by 50 percent over the last decade. The latest study, published in Nature Geoscience, finds that the intensity of these fires is also growing, mainly because of the lengthening of the summer burning season. These intense, late-season fires burn deeper into the soil, igniting peat in ecosystems that ordinarily act as long-term carbon sinks and that have kept large amounts of carbon dioxide fixed as organic material and out of the atmosphere.

As a result, Alaskan wildfires released roughly twice as much carbon dioxide into the air during the 2000s than had the average for the previous five decades, the study found. The sharp rise in emissions means that Alaska’s interior boreal regions have become net carbon dioxide emitters.

“There is no way these systems are serving as a net carbon sink anymore,” Merritt Turetsky, a biology professor at the University of Guelph in Ontario and lead author of the study, said in an interview. Read more…