“Less Meat Less Heat (LMLH) is a grassroots, non-profit organisation dedicated to shifting societal attitudes towards meat consumption and as such curtailing agriculture’s damaging influence on the global climate. Our work encompasses educating the public through sound science about the massive carbon footprint of beef and lamb. Through helping individuals transition to low-carbon eating habits we aim to leverage the power of individual action as the best tool for mitigating the threat of climate change.

From the home page of Less Meat Less Heat website

Cows belch often.

They are ruminants, mammals that enlist microbes to ferment plants they ingest in a specialised stomach prior to digestion. This symbiosis means they able to exist on a diet high in cellulose, a key constituent of grass.

Only it also means that cows belch a lot. The bacteria that assist the cow to digest cellulose include methanogens that produce methane as a metabolic byproduct. This gas builds up and has to be let out. It’s similar for us only we tend to fart more than belch.

The problem for the climate change conundrum is that methane is a greenhouse gas over 23 times more potent than carbon dioxide. And methane is what ruminants burp.

An average dairy cow puts out around 100 kg of methane each year. Depending on how you calculate it, this is roughly equivalent to greenhouse gas emissions from a car. Beef cattle belch a little less so it takes two to match up to a car. The global numbers are interesting though. There are a little over 1 billion cars on earth and somewhere between 1.3 and 1.5 billion cows.

As far as the greenhouse gas balance goes, human consumption of meat and dairy products is roughly equivalent to the impact from our cars.

Note that this is without counting emissions from the clearing of woody vegetation to find or grow enough grass for the livestock.

Methane from ruminants (cattle, goats and sheep) makes up over 40% of greenhouse gas emissions from agriculture and up to 14% of all global emissions.

This is a big deal.

So much so that some people, such as those responsible for the quote above, are adamant that meat from cows and sheep is an environmental disaster. Only there is a significant reason why agriculture is often left out of any national carbon accounting even though it is the source of a third of global emissions.

People have to eat.

In the next hour as souls depart and new ones join the human diaspora there will be a change. In an hours time, there will be at least 9,700 more souls on the planet than we have right now. Funerals and births are not yet in balance.

Assuming that these souls are nourished around 500ha of productive land will be needed to grow enough calories for their daily needs.

A year from now when 83 million new souls have joined, the planet has to give up 4.6 million ha of productive land to feed them.

This crude calculation makes some simple assumptions. Calorie intake is 20% more than is needed to avoid starvation but half that consumed by the average US citizen. Calories come from growing wheat, and not from animal products. All else is equal, so the 7.5 billion souls already here are being fed and watered too.

Having meandered away to the big picture reality, let’s look again at the “massive carbon footprint of beef and lamb” and “low-carbon eating habits… as the best tool for mitigating the threat of climate change.”

If we all grew dreadlocks and avoided meat, then the calorific conversion from land to the plate would be improved. No need for the respiration of animals burning the calories before we got at them. And no need for their nasty methane emissions.

But we still need 2,500 calories per person per day.

If all this energy came from plant products, agriculture was near perfect efficiency and all else was equal, the 7.5 billion souls need a little over 4 million km2 of productive land to generate enough vegetarian calories.

There are roughly 48 million km2 of agricultural land on earth, so we should be fine. Plus there are ever more sophisticated technologies that can intensify food production to deliver greater yield from smaller areas. Hydroponics is a fine example.

So in theory at least there is enough land to feed perhaps 9 or even 11 billion souls. No worries and no fuss.

And as ‘less meat, less heat’ proclaim, without meat, we can mitigate the threat of climate change.

If only it were that simple.