|Dear USCB Science Line,
Hello! How are you all are doing? With all do respect I have read your story online about cows that fart and burp on your website that was dated back in 2011 ( here. I wanted to let you know that not only cows fart and burp but all animals and us humans burp and fart too sometimes. Now I’m all for improving the environment and climate and healthy food from plants which provide health benefits. So why should we do something about cows when all animals and humans do the same thing? I don’t see what will solve the problem when it comes to burps and farts. Can you please email me back with an answer? I’m sorry, please do forgive me for sending this email if you all happen to not like what I wrote here. Thanks and God Bless!|
|Question Date: 2019-11-28|
You’re right. As other answers mentioned, cows are not the only methane producers. It’s all about quantity If people ate less beef, we’d have fewer cows, so less methane would be produced. This is also true for dairy products (milk, cheese, etc.). We wouldn’t get rid of methane production, there would just be less of it.
Of course, nothing is that simple. If we weren’t eating beef and dairy products, we’d be eating something else, which might also result in greenhouse gasses. But a plant-based diet tends to produce fewer greenhouse gasses because it’s more efficient to eat corn than to feed the corn to a cow, then eat the cow. The second law of thermodynamics tells us that every time energy is transformed, some becomes heat (a form of energy) and dissipates (spreads out). All the work that a cow’s body has to do uses up a lot of energy.
You can see the general idea for yourself. Things at the bottom of the food chain do photosynthesis. We call them producers. They might be grass or algae, or lots of other things. The things that eat them are called primary consumers. They may be cows, crickets, zooplankton, or lots of other things. Things that eat primary consumers are called secondary consumers. They may be wolves, robins, trout, or lots of other things. Now look at any natural community. You will see lots and lots of producers, some primary consumers, and maybe, if you’re lucky, a secondary consumer. In other words, the higher up the food chain you go, the more energy has been “lost” along the way. It takes a lot of producers to support a primary consumer, but a lot more to support a secondary consumer.
Here’s a tough question for you. Think about all the groceries you ate last month. Estimate how much they weighed. You did not gain that much weight last month, so where did all that matter go? Hint: It did not become energy.
Thanks for asking,
Thanks for your great question and also for your skepticism. Your inquiry's a clear sign that you're a budding scientist, someone who challenges what they've read or been told.
As you note, cows and other ruminant artiodactyls (mammals with cloven hooves) are not alone in producing methane--the digestive tracts of most organisms also produce this greenhouse gas. That many animals produce methane, however, doesn't mean that emissions from "cows" aren't of concern. Just because everything "toots," doesn't mean we shouldn't try to reduce production of this greenhouse gas when possible. Indeed, it is within our grasp to minimize unnecessary "toots."
Cows are a luxury in the sense that humans could get by just fine with fewer or none of them, thereby reducing the amount of methane contributed to the atmosphere. By the same token, most of us could get by driving more efficient cars, or not having cars at all.
Sadly, societies are slow to accept the idea that everyone can make a difference when it comes to limiting greenhouse gases and slowing climate change. What's more, some people actively argue that humans are not contributing to climate change, something flatly contradicted by mountains of scientific evidence. It's always good to question what you hear. But sometimes crazy-sounding ideas like the Earth is not flat, or cows contribute to global warming, turn out to be true.
I would first point out that the answers previously posted on ScienceLine do not take a stance on whether or not we should do anything about burps and farts of animals/humans (though some get close); they answer the question that was asked, namely "Do cow farts contribute to global warming?" As cow farts (and burps) release methane, a potent greenhouse gas (GHG), into the atmosphere, these actions do contribute to global warming. To return to the current question, one could now ask why the focus is on cows and their farts/burps rather than those of other organisms, and also whether humans should act to reduce the impact of these animals on global warming.
Cows receive much attention when it comes to methane as a greenhouse gas (GHG) because:
(1) there are a lot of them ( ~1.4 billion worldwide); and
(2) each cow releases a relatively large amount of methane, ~200-500 L per day, compared to, for example, ~0.7 L/day for a human. Thus, cows farts/burps contribute ~50x more methane than human farts. [Side note - part of the reason for the large difference in methane per cow vs. per human is that cows are ruminants, a type of animal with a digestive system that is (as a side effect) especially productive of methane, while humans are not.]
As far as other animals, wild ruminants number less than 0.1 billion (15x less than cows), while other livestock ruminants (sheep, goats, etc.) number ~2 billion (~1.4x more than cows). However, the methane production each of these animals is 1/10x (or less) that of a cow.
Thus, the global warming effect of cow burps and farts is relatively large compared to that due to burps and farts of other animals.
Next is the question of whether the contribution of cows on global warming is large compared to other sources. Government estimates put the methane produced by cattle and similar livestock at ~40% of the methane released into the atmosphere due to human-related activities. In turn, methane accounts for ~15% of all human-derived GHG emissions. To put this into context, the methane from cows accounts for ~6% (0.4 * 15% = 6%) of all human GHG emissions, the same as the amount used from heating and cooking in buildings and only 2x smaller than the emissions from transportation (i.e., cars, airplanes, boats, etc.) which account for ~14%. If the effects from the latter two sources are considered significant, then the effect of cows presumably is as well.
So, should humans attempt to control cow-produced methane? The International Panel on Climate Change has issued a report on the effects of global warming reaching 1.5°C higher than a threshold level, with the predicted consequences being dire. To prevent that temperature rise, the panel states that GHG emissions must be reduced. Note though, that the source of the GHG doesn't matter as far as reduction, and one might choose to make changes that are easy, effective, and feasible. While reducing the emissions from cars may not be easy to achieve, decreasing the methane from cows might be. Recent research suggests that adding just 1% of a seaweed to cattle feed can cut their methane emissions by more than half. Thus, worrying about cow burps and farts may be a promising avenue for meeting GHG emission goals.
Great question! Like you say, other animals burp and fart: so why does everyone talk about cows? There are two major reasons.
1. Humans eat a LOT of beef and dairy, so we raise a lot of cows- much more than most other livestock animals.
2. Cows eat grass, which is difficult to digest- humans can’t do it! Cows can, because they have 4 stomachs. These extra stomachs allow them to digest the tough grass, but the process releases a lot more methane than other animals (like humans) which eat things that are easier to break down. Sheep and goats also eat grass, and produce a lot of methane, but humans don’t raise nearly as many of those animals.
For these reasons, we estimate that cows contribute about 70% of greenhouse gas due to livestock.
To summarize: cow farts and burps are a bit worse than other animals, because they release extra methane when they digest tough grass. Some scientists think that this problem could be fixed by feeding cows seaweed, which is full of nutrients and easier to digest.
There is another environmental issue related to cows, which is (arguably) a bigger problem than the methane from digestions. There are a lot of cows, and cows are big: so they have to eat a LOT of grass to get enough food. So we need a huge amount of land for all this grass to grow- and people often cut down forests to make room.
Source: Food and Agriculture Organization of the United Nations. link here
It is always okay to ask questions. In response to your question, it is true that humans and other animals fart and burp, but a much smaller amount of the gas that we produce is methane. People focus on cattle, because they burp the most methane out of all of our livestock. Also, since cattle on ranches don't get to control their numbers or their diets, it's not really their fault. It all depends on how much beef people want to buy, and what we feed them.
On the other hand, things that people do, such as drilling for oil and natural gas with leaky equipment releases more methane to the atmosphere than cows do. Using less oil and gas and not letting what we are using escape is more important than reducing beef consumption, but it is harder, because everything we do requires energy. Not everything requires beef. I hope this helps.
Fermenting vegetation releases methane much more than the digestion that we do. As a result, yes, while people do make methane, cows make more.
However, the main way we humans are altering the climate is with carbon dioxide, not methane. Methane does not last long in our atmosphere (it combines with oxygen to make carbon dioxide and water).
Blessings to you too - I like what you say! I agree - we want to think beyond cow burps!
1. I searched hard to find out about human burps vs cow burps, but the only thing I found was about termite methane emissions = 1% - 3% of all methane emissions:
"Methane is a greenhouse gas about 30 times more potent than carbon dioxide, and increasing industrial and agricultural emissions are a major contributor to global warming. Globally, it is estimated that termites are responsible for about one to three per cent of all methane emissions. Nov 27, 2018".
2. The following link takes you to an article where you will see a pie chart that estimates the contributions from all the sources of methane emissions - could 'enteric fermentation and manure management really contribute more methane than gas and petroleum??!! -
Click Here to return to the search form.
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