Tag Archives: climate change

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More CO2 is Good, Right?

Yesterday, May 10, 2013, scientists published new measures of atmospheric carbon dioxide (CO2). For the first time in human history CO2 levels reached an average of 400 parts per million (ppm). This is particularly troubling since CO2 has long been known as the most potent heat trapping component of the atmosphere. The sobering milestone was recorded from the Mauna Loa Observatory in Hawaii — monitoring has been underway at the site since the mid-1950s.

This has many climate scientists re-doubling their efforts to warn of the consequences of climate change, which is believed to be driven by human activity and specifically the generation of atmospheric CO2 in ever increasing quantities. But not to be outdone, the venerable Wall Street Journal — seldom known for its well-reasoned scientific journalism — chimed in with an op-ed on the subject. According to the WSJ we have nothing to worry about because increased levels of CO2 are good for certain crops and the Earth had historically much higher levels of CO2 (though pre-humanity).

Ashutosh Jogalekar over at The Curious Wavefunction dissects the WSJ article line by line:

Since we were discussing the differences between climate change “skeptics” and “deniers” (or “denialists”, whatever you want to call them) the other day this piece is timely. The Wall Street Journal is not exactly known for reasoned discussion of climate change, but this Op-Ed piece may set a new standard even for its own naysayers and skeptics. It’s a piece by William Happer and Harrison Schmitt that’s so one-sided, sparse on detail, misleading and ultimately pointless that I am wondering if it’s a spoof.

Happer and Schmitt’s thesis can be summed up in one line: More CO2 in the atmosphere is a good thing because it’s good for one particular type of crop plant. That’s basically it. No discussion of the downsides, not even a pretense of a balanced perspective. Unfortunately it’s not hard to classify their piece as a denialist article because it conforms to some of the classic features of denial; it’s entirely one sided, it’s very short on detail, it does a poor job even with the little details that it does present and it simply ignores the massive amount of research done on the topic. In short it’s grossly misleading.

First of all Happer and Schmitt simply dismiss any connection that might exist between CO2 levels and rising temperatures, in the process consigning a fair amount of basic physics and chemistry to the dustbin. There are no references and no actual discussion of why they don’t believe there’s a connection. That’s a shoddy start to put it mildly; you would expect a legitimate skeptic to start with some actual evidence and references. Most of the article after that consists of a discussion of the differences between so-called C3 plants (like rice) and C4 plants (like corn and sugarcane). This is standard stuff found in college biochemistry textbooks, nothing revealing here. But Happer and Schmitt leverage a fundamental difference between the two – the fact that C4 plants can utilize CO2 more efficiently than C3 plants under certain conditions – into an argument for increasing CO2 levels in the atmosphere.

This of course completely ignores all the other potentially catastrophic effects that CO2 could have on agriculture, climate, biodiversity etc. You don’t even have to be a big believer in climate change to realize that focusing on only a single effect of a parameter on a complicated system is just bad science. Happer and Schmitt’s argument is akin to the argument that everyone should get themselves addicted to meth because one of meth’s effects is euphoria. So ramping up meth consumption will make everyone feel happier, right?

But even if you consider that extremely narrowly defined effect of CO2 on C3 and C4 plants, there’s still a problem. What’s interesting is that the argument has been countered by Matt Ridley in the pages of this very publication:

But it is not quite that simple. Surprisingly, the C4 strategy first became common in the repeated ice ages that began about four million years ago. This was because the ice ages were a very dry time in the tropics and carbon-dioxide levels were very low—about half today’s levels. C4 plants are better at scavenging carbon dioxide (the source of carbon for sugars) from the air and waste much less water doing so. In each glacial cold spell, forests gave way to seasonal grasslands on a huge scale. Only about 4% of plant species use C4, but nearly half of all grasses do, and grasses are among the newest kids on the ecological block.

So whereas rising temperatures benefit C4, rising carbon-dioxide levels do not. In fact, C3 plants get a greater boost from high carbon dioxide levels than C4. Nearly 500 separate experiments confirm that if carbon-dioxide levels roughly double from preindustrial levels, rice and wheat yields will be on average 36% and 33% higher, while corn yields will increase by only 24%.

So no, the situation is more subtle than the authors think. In fact I am surprised that, given that C4 plants actually do grow better at higher temperatures, Happer and Schmitt missed an opportunity for making the case for a warmer planet. In any case, there’s a big difference between improving yields of C4 plants under controlled greenhouse conditions and expecting these yields to improve without affecting other components of the ecosystem by doing a giant planetary experiment.

Read the entire article after the jump.

Image courtesy of Sierra Club.

 

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Geoengineering As a Solution to Climate Change

Experimental physicist David Keith has a plan: dump hundreds of thousands of tons of atomized sulfuric acid into the upper atmosphere; watch the acid particles reflect additional sunlight; wait for global temperature to drop. Many of Keith’s peers think this geoengineering scheme is crazy, least of which are the possible unknown and unmeasured side-effects, but this hasn’t stopped the healthy debate. One thing is becoming increasingly clear — humans need to take collective action.

[div class=attrib]From Technology Review:[end-div]

Here is the plan. Customize several Gulfstream business jets with military engines and with equipment to produce and disperse fine droplets of sulfuric acid. Fly the jets up around 20 kilometers—significantly higher than the cruising altitude for a commercial jetliner but still well within their range. At that altitude in the tropics, the aircraft are in the lower stratosphere. The planes spray the sulfuric acid, carefully controlling the rate of its release. The sulfur combines with water vapor to form sulfate aerosols, fine particles less than a micrometer in diameter. These get swept upward by natural wind patterns and are dispersed over the globe, including the poles. Once spread across the stratosphere, the aerosols will reflect about 1 percent of the sunlight hitting Earth back into space. Increasing what scientists call the planet’s albedo, or reflective power, will partially offset the warming effects caused by rising levels of greenhouse gases.

The author of this so-called geoengineering scheme, David Keith, doesn’t want to implement it anytime soon, if ever. Much more research is needed to determine whether injecting sulfur into the stratosphere would have dangerous consequences such as disrupting precipitation patterns or further eating away the ozone layer that protects us from damaging ultraviolet radiation. Even thornier, in some ways, are the ethical and governance issues that surround geoengineering—questions about who should be allowed to do what and when. Still, Keith, a professor of applied physics at Harvard University and a leading expert on energy technology, has done enough analysis to suspect it could be a cheap and easy way to head off some of the worst effects of climate change.

According to Keith’s calculations, if operations were begun in 2020, it would take 25,000 metric tons of sulfuric acid to cut global warming in half after one year. Once under way, the injection of sulfuric acid would proceed continuously. By 2040, 11 or so jets delivering roughly 250,000 metric tons of it each year, at an annual cost of $700 million, would be required to compensate for the increased warming caused by rising levels of carbon dioxide. By 2070, he estimates, the program would need to be injecting a bit more than a million tons per year using a fleet of a hundred aircraft.

One of the startling things about Keith’s proposal is just how little sulfur would be required. A few grams of it in the stratosphere will offset the warming caused by a ton of carbon dioxide, according to his estimate. And even the amount that would be needed by 2070 is dwarfed by the roughly 50 million metric tons of sulfur emitted by the burning of fossil fuels every year. Most of that pollution stays in the lower atmosphere, and the sulfur molecules are washed out in a matter of days. In contrast, sulfate particles remain in the stratosphere for a few years, making them more effective at reflecting sunlight.

The idea of using sulfate aerosols to offset climate warming is not new. Crude versions of the concept have been around at least since a Russian climate scientist named Mikhail Budkyo proposed the idea in the mid-1970s, and more refined descriptions of how it might work have been discussed for decades. These days the idea of using sulfur particles to counteract warming—often known as solar radiation management, or SRM—is the subject of hundreds of papers in academic journals by scientists who use computer models to try to predict its consequences.

But Keith, who has published on geoengineering since the early 1990s, has emerged as a leading figure in the field because of his aggressive public advocacy for more research on the technology—and his willingness to talk unflinchingly about how it might work. Add to that his impeccable academic credentials—last year Harvard lured him away from the University of Calgary with a joint appointment in the school of engineering and the Kennedy School of Government—and Keith is one of the world’s most influential voices on solar geoengineering. He is one of the few who have done detailed engineering studies and logistical calculations on just how SRM might be carried out. And if he and his collaborator James ­Anderson, a prominent atmospheric chemist at Harvard, gain public funding, they plan to conduct some of the first field experiments to assess the risks of the technique.

Leaning forward from the edge of his chair in a small, sparse Harvard office on an unusually warm day this winter, he explains his urgency. Whether or not greenhouse-gas emissions are cut sharply—and there is little evidence that such reductions are coming—”there is a realistic chance that [solar geoengineering] technologies could actually reduce climate risk significantly, and we would be negligent if we didn’t look at that,” he says. “I’m not saying it will work, and I’m not saying we should do it.” But “it would be reckless not to begin serious research on it,” he adds. “The sooner we find out whether it works or not, the better.”

The overriding reason why Keith and other scientists are exploring solar geoengineering is simple and well documented, though often overlooked: the warming caused by atmospheric carbon dioxide buildup is for all practical purposes irreversible, because the climate change is directly related to the total cumulative emissions. Even if we halt carbon dioxide emissions entirely, the elevated concentrations of the gas in the atmosphere will persist for decades. And according to recent studies, the warming itself will continue largely unabated for at least 1,000 years. If we find in, say, 2030 or 2040 that climate change has become intolerable, cutting emissions alone won’t solve the problem.

“That’s the key insight,” says Keith. While he strongly supports cutting carbon dioxide emissions as rapidly as possible, he says that if the climate “dice” roll against us, that won’t be enough: “The only thing that we think might actually help [reverse the warming] in our lifetime is in fact geoengineering.”

[div class=attrib]Read the entire article following the jump.[end-div]

Environs, tD

Climate Change Report

No pithy headline. The latest U.S. National Climate Assessment makes sobering news. The full 1,146 page report is available for download here.

Over the next 30 years (and beyond), it warns of projected sea-level rises along the Eastern Seaboard of the United States, warmer temperatures across much of the nation, and generally warmer and more acidic oceans. More worrying still are the less direct consequences of climate change: increased threats to human health due to severe weather such as storms, drought and wildfires; more vulnerable infrastructure in regions subject to increasingly volatile weather; and rising threats to regional stability and national security due to a less reliable national and global water supply.

[div class=attrib]From Scientific American:[end-div]

The consequences of climate change are now hitting the United States on several fronts, including health, infrastructure, water supply, agriculture and especially more frequent severe weather, a congressionally mandated study has concluded.

A draft of the U.S. National Climate Assessment, released on Friday, said observable change to the climate in the past half-century “is due primarily to human activities, predominantly the burning of fossil fuel,” and that no areas of the United States were immune to change.

“Corn producers in Iowa, oyster growers in Washington State, and maple syrup producers in Vermont have observed changes in their local climate that are outside of their experience,” the report said.

Months after Superstorm Sandy hurtled into the U.S. East Coast, causing billions of dollars in damage, the report concluded that severe weather was the new normal.

“Certain types of weather events have become more frequent and/or intense, including heat waves, heavy downpours, and, in some regions, floods and droughts,” the report said, days after scientists at the National Oceanic and Atmospheric Administration declared 2012 the hottest year ever in the United States.

Some environmentalists looked for the report to energize climate efforts by the White House or Congress, although many Republican lawmakers are wary of declaring a definitive link between human activity and evidence of a changing climate.

The U.S. Congress has been mostly silent on climate change since efforts to pass “cap-and-trade” legislation collapsed in the Senate in mid-2010.

…

The advisory committee behind the report was established by the U.S. Department of Commerce to integrate federal research on environmental change and its implications for society. It made two earlier assessments, in 2000 and 2009.

Thirteen departments and agencies, from the Agriculture Department to NASA, are part of the committee, which also includes academics, businesses, nonprofits and others.

‘A WARNING TO ALL OF US’

The report noted that of an increase in average U.S. temperatures of about 1.5 degrees F (.83 degree C) since 1895, when reliable national record-keeping began, more than 80 percent had occurred in the past three decades.

With heat-trapping gases already in the atmosphere, temperatures could rise by a further 2 to 4 degrees F (1.1 to 2.2 degrees C) in most parts of the country over the next few decades, the report said.

[div class=attrib]Read the entire article following the jump.[end-div]