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Want to slow climate change? Stop killing sharks

by bukaroso Posted on September 30, 2015

Want to slow climate change? Stop killing sharks

By on 30 Sep 2015commentsShare

With shark attacks on the rise in Australia, a handful of researchers gathered in Sydney on Tuesday to discuss potential shark repelling technologies. A new study published in Nature Climate Change, however, suggests that repelling sharks from vegetated coastal areas — or even more drastic options like partially culling shark populations — could be bad news for the climate. (And, it probably goes without saying, bad news for the sharks.) The Guardian reports:

With about 90% of the world’s sharks and other large predator fish wiped out through overfishing and culling, potential prey such as sea turtles, stingrays and crabs have flourished.

As a result, turtles have been free to munch their way through larger amounts of seagrass and crabs have been able to disturb a greater amount of seabed sediment. Such consequences have “far reaching consequences on carbon cycling and, by implication, our ability to ameliorate climate change impacts” the paper warns.

The research, conducted by academics from Deakin University, University of Technology Sydney and Griffith University, said vegetated coastal habitats store 50% of the carbon buried in all ocean sediments, representing about 25bn tonnes.

The links between predators and vegetated coastal areas (like salt marshes and mangroves) have been previously established, but this study is one of the first to take a deep dive into the actual mechanisms at play and connect these mechanisms to carbon sequestration and climate change.

The scientists write, “Sea turtles and dugongs preferentially forage in seagrass microhabitats that are low in predation risk. Seagrass microhabitats associated with low predation risk have lower [carbon] stocks than do microhabitats associated with high predation risk.” Basically, in the presence of animals like tiger sharks, grazers like sea turtles and manatees tend to feed elsewhere, and slow-growing, carbon-trapping seagrass is allowed to grow unadulterated.

For further evidence of sharks’ utility, just take a look at this animated diagram, as published in Nature Climate Change*:

via Giphy

Immediately, it should be obvious that the derpshark (Carcharodon derpius) and its toothy relatives are not only important keystone species, they are also significantly less frightening than one might have imagined. (The derpshark is, however, deeply terrifying in a more existential sense, much like the fact of Go-Gurt or Justin Bieber’s monkey.)

So Grist’s advice to the Australian policymakers responsible for solving the shark attack problem: Skip the “underwater gates that release electro-magnetic fields and flexible plastic nets” to repel sharks. Instead, why not simply mandate surfers to wear large shark costumes instead of wetsuits? Fighting climate change and shark bites with the same stick — that’s a policy with some teeth.

*Diagram not actually published in Nature Climate Change. Which you probably could have guessed.

Source:

Shark culling could indirectly accelerate climate change, study warns

, The Guardian.

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Want to slow climate change? Stop killing sharks

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It’s virtually certain that the IPCC needs to dump its “very likely” crap

by LinTarleton Posted on April 22, 2014

What are they on about?

It’s virtually certain that the IPCC needs to dump its “very likely” crap

By

Shutterstock

It’s hard to understand what the U.N. Intergovernmental Panel on Climate Change is yammering on about.

The IPCC — which has released its latest climate assessment in three huge installments — uses confusing language to describe how certain it is about its findings. This could be misleading the public into thinking scientists are less certain than they really are about global warming, according to a new study.

Consider this statement from the first installment of the IPCC report, which came out in September: “It is very likely that the number of cold days and nights has decreased and the number of warm days and nights has increased on the global scale.”

By using the phrase “very likely,” the scientists mean that there’s a 90 to 99 percent likelihood that the statement is true. But when normal people read “very likely” in a statement like that, they think the IPCC’s scientists are just 55 to 90 percent confident in it, according to the new study, which was published in the journal Nature Climate Change.

Here are the seven main descriptors that IPCC report authors are told to use, and what percentage of certitude they’re meant to communicate:

Nature Climate Change

The researchers behind the new study showed a series of IPCC statements containing these terms to 1,304 people from 25 different countries. The people were asked to judge the scientists’ confidence levels — and they got it very wrong.

“In all samples,” the researchers wrote, “people interpreted the probabilistic pronouncements of the IPCC regressively” — meaning they would underestimate high probabilities and overestimate low ones. The biggest misinterpretations came when the word “very” was used.

The researchers say people would better understand if the IPCC used numbers to express its confidence levels.

This isn’t the first time that the IPCC’s approach to communicating certainty has been found to be flawed. Similar findings were published in 2009 and in 2011. And an independent review of the IPCC pointed out this problem in 2010. But the IPCC persists in using this misleading gibberish. And if that weren’t bad enough, the panel still doesn’t understand how to effectively use the internet.


Source
The interpretation of IPCC probabilistic statements around the world, Nature Climate Change

John Upton is a science fan and green news boffin who tweets, posts articles to Facebook, and blogs about ecology. He welcomes reader questions, tips, and incoherent rants: johnupton@gmail.com.

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It’s virtually certain that the IPCC needs to dump its “very likely” crap

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Corn waste-based ethanol could be worse for the climate than gasoline

by Steven Posted on April 22, 2014

Corn waste-based ethanol could be worse for the climate than gasoline

By

Ron Nichols, USDA

Young corn growing in the residue of the previous crop.

A lot of carbon-rich waste is left behind after a cornfield is stripped of its juicy ears. It used to be that the stalks, leaves, and detrital cobs would be left on fields to prevent soil erosion and to allow the next crop to feast on the organic goodness of its late brethren. Increasingly, though, these leftovers are being sent to cellulosic ethanol biorefineries. Millions of gallons of biofuels are expected to be produced from such waste this year — a figure could rise to more than 10 billion gallons in 2022 to satisfy federal requirements.

But a new study suggests this approach may be worse for the climate, at least in the short term, than drilling for oil and burning the refined gasoline. The benefits of cellulosic biofuel made from corn waste improve over the longer term, but the study, published online Sunday in Nature Climate Change, suggests that the fuel could never hit the benchmark set in the 2007 U.S. Energy Independence and Security Act, which requires that cellulosic ethanol be 60 percent better for the climate than traditional gasoline.

The problem is that after corn residue is torn out and hauled away from a farm field, more carbon is lost from the soil. This problem is pervasive throughout the cornbelt, but it’s the most pronounced in Minnesota, Iowa, and Wisconsin, owing in part to the high carbon contents of soils there.

Researchers used a supercomputer to run models to estimate the effect of removing corn residue from 128 million acres of farmland in 12 corn-farming states. Removing the residue was found to release 50 to 80 grams of carbon dioxide from the exposed soil for every megajoule of biofuel produced. Add to that figure the biofuel’s tailpipe CO2 emissions and, voila, you get an average of 100 grams of CO2 released for every megajoule of power produced — which is 7 percent worse than emissions from regular old gasoline.

The key findings are shown in the following graph from the paper. The top line shows that soil organic carbon (SOC) is gradually lost over nine years when corn residue is left in place. But when the residue is hauled off to be turned into biofuel, as shown in the dashed lower line, the loss of soil carbon is more rapid. The loss of such soil carbon is a blow for the farm — crops need that material to grow. But it’s also a blow for the climate, because the carbon ends up in the atmosphere as a greenhouse gas.

Nature Climate ChangeClick to embiggen.

The researchers found that the loss of soil carbon is an issue regardless of whether some of the residue is removed from a field or all of it. “If less residue is removed, there is less decrease in soil carbon, but it results in a smaller biofuel energy yield,” said report coauthor Adam Liska, an assistant professor at the University of Nebraska at Lincoln.

The research was funded with $500,000 from the federal government — which was quick to pan the results.

An EPA spokeswoman told the AP that the study “does not provide useful information relevant to the life cycle greenhouse gas emissions from corn stover ethanol.” And the biofuels industry complained that the researchers did not give a good explanation for why their conclusions contradicted other recent studies.

But the AP has previously exposed gaping holes in the EPA’s own studies, which have concluded that ethanol provides big climate benefits.

We asked Liska how officials could use his findings to help slow down global warming. He suggested that they start by using their ears (not the corn kind). “If emissions are going to be decreased, the EPA should accept these findings as valid,” he replied.


Source
Biofuels from crop residue can reduce soil carbon and increase CO2 emissions, Nature Climate Change
Study casts doubt on climate benefit of biofuels from corn residue, University of Nebraska
Study: Fuels from corn waste not better than gas, The Associated Press

John Upton is a science fan and green news boffin who tweets, posts articles to Facebook, and blogs about ecology. He welcomes reader questions, tips, and incoherent rants: johnupton@gmail.com.

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Crop-munching pests are traveling north as the climate changes

by Cindy Lin Posted on September 3, 2013

Crop-munching pests are traveling north as the climate changes

By

Sergey Yeliseev

Gypsy moth larva, a pest in America’s forests, is even more pesky these days.

Pests are packing their metaphorical bags and heading for fresh starts nearer the North Pole as the climate warms around them.

Beetles, moths, fungi, and other pests that afflict forests and crops in the Northern Hemisphere are expanding their ranges northward by an average of 24 feet every day.

That’s according to British scientists who studied the records of infestations of 470 pests around the world since 1960 and measured the rate at which their ranges appeared to be shifting. They say their findings reveal a potential threat to food security posed by global warming.

The northerly march “is more rapid than that reported for many wild species,” the scientists wrote in a paper published Sunday in the journal Nature Climate Change. And it’s “nearly identical” to what would be expected from rising temperatures.

The findings show that termite pests are moving poleward the most quickly, at an average rate of 177 feet daily. Butterfly, moth, thrip, and beetle pests are moving north at an average of about 70 feet per day.

“There has been much research over the past couple of decades showing that wild populations of plants and animals have been moving poleward in response to warming,” study lead author and University of Exeter biosciences research fellow Dan Bebber told Grist. “Our paper shows that this is happening in pests as well.”

The northward movement of pests coincides with new farming practices that are pushing farms closer to the poles. But Bebber is convinced that the pests are moving in response to the changing climate. “Changes in farming practices and land use would probably lead to simple range expansion of pests, rather than a directional shift as we have demonstrated,” he said.

John Upton is a science fan and green news boffin who tweets, posts articles to Facebook, and blogs about ecology. He welcomes reader questions, tips, and incoherent rants: johnupton@gmail.com.

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