Environment

Vicious cycle ties warmer cow food to higher methane emissions

Vicious cycle ties warmer cow ...
When food is more difficult to digest, it means cows produce more methane in the process
When food is more difficult to digest, it means cows produce more methane in the process
View 1 Image
When food is more difficult to digest, it means cows produce more methane in the process
1/1
When food is more difficult to digest, it means cows produce more methane in the process

As major exponents of greenhouse gases that warm the Earth, what cows consume is increasingly gaining attention from scientists trying to apply the brakes to global methane emissions. The latest promising discovery in this area comes from an international team of researchers, who have found that livestock plant food grown in warmer climates leads to higher methane releases, and could potentially be inhibiting milk and meat production at the same time.

Methane emitted by cows, or from any source for that matter, is a problem because it is 25 times more potent than carbon dioxide as a greenhouse gas, due to its superior heat-trapping abilities. Meanwhile, global meat production is on the rise, from 71 million tons in 1961 to 318 million tons in 2014.

So scientists have been looking at the effects of livestock diets, and how they might be tweaked to reduce the amount of methane produced by the world's growing bovine population. Last year, Australian scientists identified a strain of seaweed that can reduce methane emissions by 99 percent, while earlier this year another research team discovered that feeding cows tropical leaves in addition to regular food could cause also cause sharp decline.

The latest research doesn't unearth new dietary supplements, rather it reveals an already existing culprit. Scientists from Royal Botanic Gardens, Kew, Scotland's Rural College, and the Senckenberg Biodiversity and Climate Research Centre in Frankfurt studied published data on forage quality, and found that nutritional value of grass was reduced at higher temperatures.

This is turn makes it harder for grazing livestock to digest the plants, and the scientists say there are a few reasons that might be. The extra heat causes plants to adapt and they may flower earlier, produce thicker leaves or possibly allow tougher invasive plants to spread into new areas and replace more nutritious species. With the plants tougher to digest, they spend longer inside the animal and produce more gas, and the scientists say this is setting in motion a vicious cycle.

"The vicious cycle we are seeing now is that ruminant livestock such as cattle produce methane which warms our planet," says Dr. Mark Lee, a research fellow at Royal Botanic Gardens, Kew. "This warmer environment alters plants so they are tougher to digest, and so each mouthful spends more time in the animals' stomach, producing more methane, further warming the planet, and the cycle continues. We need to make changes to livestock diets to make them more environmentally sustainable."

With an eye to the future, the scientists used published empirical models to estimate how changes to the climate will impact global methane production. They found that methane production increased by 0.9 percent with a 1 °C temperature rise (1.8 °F), and by 4.5 percent with a 5 °C rise (9 °F). They expect this to be a worldwide trend, but did identify hotspots in North America, Central/Eastern Europe and Asia, places where livestock farming is increasing and climate change is expected to hit hardest.

"Now is the time to act, because the demand for meat-rich diets is increasing around the world," says Lee. "Our research has shown that cultivating more nutritious plants may help us to combat the challenges of warmer temperatures."

The research paper was published in the journal Biogeosciences.

Source: Royal Botanic Gardens, Kew

7 comments
SteveCase
Nick Lavars writes, "Methane emitted by cows, or from any source for that matter, is a problem because it is 25 times more potent than carbon dioxide as a greenhouse gas, due to its superior heat-trapping abilities." You know what? That tells us nothing about how much a given amount of methane in the air will run up the temperature. So Nick, if you read the comments section how much will the temperature, in degrees, go up if, for example, the amount of methane in the air doubles, and how long, in years, will that take? Answer those two questions and your readers will appreciate it. Steve Case - Milwaukee, WI
Daishi
@SteveCase I think the science of accurately relating it to temperature rise is complicated and subject to a lot of details and debate. Something not mentioned here is that methane dissipates from the atmosphere faster than CO2 and the standard figure used is averaged over 100 years. Methane traps 100 times more heat than CO2 over 5 years and 72 times more heat over 20 years and then falls off after that. Methane is only 14% of green house gas but could have more impact than CO2. Source here: http://www.onegreenplanet.org/animalsandnature/methane-vs-carbon-dioxide-a-greenhouse-gas-showdown/
aksdad
Steve, Nick doesn't know. Neither does virtually everyone who thinks methane is a potent greenhouse gas. Why bother with science and physics when saying things like "25 times more potent" sounds so much scarier? Telling the reader that there is 225 times as much CO2 (405 ppm) as methane (1.79 ppm) in the atmosphere so methane's effect is only 20% of CO2 is factual, but not nearly as scary. Of course mentioning that there is 62 times as much water vapor (25,000 ppm) as CO2 and that H2O absorbs a much broader spectrum of infrared radiation (as well as reflecting sunlight--off the clouds--and preventing it from even reaching the lower atmosphere) and is a much more potent greenhouse gas than either methane or CO2 is also factual but even less scary. And if you showed the reader that atmospheric methane is barely rising, perhaps 1.5 ppm in 30 years, even when drilling for natural gas is at an all-time high, then you might just put him to sleep because, of course, there's absolutely nothing to worry about. But running around with your hair on fire is much more fun. https://www.epa.gov/climate-indicators/climate-change-indicators-atmospheric-concentrations-greenhouse-gases (click on Figure 2. Global Atmospheric Concentration of Methane Over Time, and by the way, ppb--parts per billion is 1,000 times smaller than ppm--parts per million)
aksdad
Sorry, I misread the graph of atmospheric methane. It has increased about 0.7 ppm in 65 years, even slower than what I wrote. See here https://www.epa.gov/climate-indicators/climate-change-indicators-atmospheric-concentrations-greenhouse-gases (click on Figure 2. Global Atmospheric Concentration of Methane Over Time, ppb--parts per billion is 1,000 times smaller than ppm--parts per million)
Daishi
Graph in question: http://i.imgur.com/RMjdBsy.png "atmospheric methane is barely rising - @aksdad" Observation of the year right there. TIL a ~40% increase in 65 years is nothing. It's so hard to see why climate change deniers aren't taken seriously.
Douglas Bennett Rogers
Desert irrigation and water cooling are probably more important than CO2 and methane, although it would go away in a few weeks if irrigation were stopped. You can easily feel the effect when living in an irrigated desert like southern California or Arizona. Afternoon wet bulbs and morning lows are around 10 degrees F higher than in the unirrigated desert. The wet bulb precisely tracks the heat content of the air.
f4ccc9a576964dcfb490f3b613abcb1b
Since there are vast amount of coal being mined, and shipped by trains for the most part in the US, no one bothered to study the 30% moisture content of coal shipped from the Powder River Basin. Deleting the areas mined by evaporation of it's moisture in the soils would of course seriously impact any calculations. Multiply the average ton of coal moisture, generally 30%, and think where it goes when removed from the sub-surface.