Before we get to the cow thing, pop quiz: Which sector creates the most greenhouse gas emissions? We've placed the list of sectors below in alphabetical order—see if you can correctly list them in order of worst offenders.

- Agriculture
- Commercial & Residential
- Electricity
- Industry
- Transportation

To force you to scroll down to see the correct answers, I will fill the space here with three videos from the seminal 1980s rock band, Bon Jovi.

You might be surprised to learn that, according to the EPA's most recent (2014) statistics, Electricity production surpasses both Transportation and Industry:

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Agriculture is the smallest chunk, but it's still significant—and increasing, which obviously needs to stop. According to the Food and Agriculture Organization of the United Nations, "Cattle (raised for both beef and milk, as well as for inedible outputs like manure and draft power) are the animal species responsible for the most emissions, representing about 65% of the livestock sector's emissions."

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The bulk of a cow's emissions are methane (44%, with 29% being nitrous dioxide and the remaining 27% carbon dioxide). So the bottom line: Methane from cows is the largest single chunk of GGEs from the Agriculture sector.

Now, an Australian professor of aquaculture may have figured out how to reduce a cow's methane output almost entirely, according to Australian Broadcasting Corporation News. James Cook University professor, Rocky De Nys, has been working with the Commonwealth Scientific and Industrial Research Organisation (CSIRO), and they've found that "adding a small amount of dried seaweed to a cow's diet can reduce the amount of methane a cow produces by up to 99 per cent."

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The researchers had already seen similar results with sheep, cutting their diet with 2% seaweed, which reduced their methane output by 50% to 70%. But with the cows, "the amount of success and reduction we saw was very surprising," Professor De Nys says.

Now, the problem is how to harvest the seaweed, which CSIRO researcher Rob Kinley calls "the number one barrier—getting enough seaweed to feed millions of cows.

"Wild harvesting isn't going to do it because it's far too expensive and the resources aren't enough, so we need to get partners on board who can produce the seaweed in a cultivation process."

By the bye, Professor De Nys revealed this surprising fact, which will disappoint schoolchildren everywhere: "The vast majority of methane comes from the cow's burp rather than the gas from the other end of the cow."