Climate Change on a Little Planet

We’re often told that if we avoid waste and live in harmony with nature, we can stop climate change. But…

Plastic bags don’t cause global warming. Recycling often does. Cattle are responsible for about 10% of global emissions. And reusable nappies cause more warming than disposable ones.

In this article, I’ll go through the things someone in a developed country can do reduce climate change, and show you how effective each actually is, backed up with the science.

The Little Planet

If I tell you that going vegetarian will reduce your greenhouse gas emissions by 1.1 tons a year, is that a little or a lot? It’s hard to know. Tons of emissions are too abstract; what we care about is actual global warming. But telling you that going vegetarian would reduce the world’s temperature by 0.000000000019 °C in 2100 doesn’t help either; there’s no easy way to take in a number with that many zeroes.

The reason that number is hard to understand is that we have 7.8 billion people on a huge planet. Anything one of us does is going to have a miniscule effect on global warming — but between us, we have a pretty large effect.

If the size of the planet and the number of humans make things hard to understand, there’s an easy solution. How about we imagine dividing the world into 7.8 billion tiny planetoids, each with just one person on? If we imagine that happens today, then I can show you the impact of your future actions on your little planetoid and the numbers will all be sensibly sized.

It’s time to meet a friend.

The Little Prince lives on a Little Planet. Coincidentally, it’s exactly 7.8 billion times smaller than Earth, and so 7.8 billion times more sensitive to greenhouse gases. So when the Little Prince flies a mile, the Little Planet warms up by exactly the same amount the Earth would if all 7.8 billion Earthlings flew a mile each. It’s remarkably easy for the Little Prince to see how he causes warming on the Little Planet because his actions aren’t mixed in with 7,799,999,999 other people’s actions.

Throughout the article I’ll tell you how much your actions would affect your very own Little Planet’s temperature in 2100. For example, for an average American, going vegetarian reduces their Little Planet’s 2100 temperature by 0.12 °C. That’s a sensibly sized number! We can compare it to a goal like ‘2°C of warming by 2100’, and see how much it helps.

In case you’re short on time, there’s a table at the very end that shows all the actions and their effect on the Little Planet.

Science and Sin

Like a Mills and Boone novel, an article on climate change has a well-established structure…

Memorable statistic, sad anecdote. Depressing statistic, terrifying statistic. Finger-pointing. Guilt, guilt. You are a terrible person for not doing more about climate change.

Can we agree not to do that here? I’m not going to subtly finger-point and you’re not going to imagine I am. Journalists love talking about blame, and how to dole it out, but that’s a) not at all backed up by the science and b) pretty stupid, because many people are ‘to blame’ for each unit of emissions.

The point about blame is a bit abstract, so here’s an example. If I buy an iPhone, who’s ‘to blame’ for the emissions — me, Steve Jobs or Apple shareholders? If I fly for work, is that on me or my employers? These aren’t questions science can answer.

Science can tell us how much I could reduce emissions by keeping my old phone for a year, or how much Apple could by using greener energy. There’s overlap there: Apple and I are going after the same emissions. But that’s okay; the real world is messy like that.

The best climate researchers talk about the impact of choices and actions rather than pointing fingers, and that’s all we’ll do here. In this article I’ll always show the impact of your choices and actions, assuming other people do their usual thing.

Method

Full technical details and sources for my method are in a long, dry post, but there are a couple of important things you should know up-front:

  • I’ll always be giving numbers for average people in the US and UK. If you eat a cow a day, you’ll have a lot more impact on emissions when you go vegetarian. I’ll give you enough details to adjust everything for your own circumstances.
  • The longer you have left on Earth, the more you’ll affect 2100 temperatures. It’s 2020 now; I’m going to assume you’ll be around until 2070. I had to pick something, and 50 years is a round number. You can approximately adjust for your own life expectancy if you like; halve the numbers for 25 years, and so on.

Note that I’m ignoring your past emissions; we’re not pointing fingers here.

Actions

Because our Little Planets are made by magically cutting the Earth into little Earth-like pieces, 2 °C, 2.5 °C, 3 °C and other warming levels cause the same amount of flooding, heatwaves and other events that they would on the Earth. All the 2100 cooling effects we find should be thought of compared to those targets. So for example:

  • Actions that cool the Little Planet by 1.0 °C are a huge deal; that gets us from 3 °C in 2100 to 2 °C in 2100, which makes a huge difference in practice.
  • Actions that cool the Little Planet by 0.1 °C are well worth doing; they reduce flooding, etc., by a noticeable amount.
  • Actions that cool the Little Planet by 0.01 °C or less have a tiny effect on climate change. Focusing on them may make things worse by diverting effort from substantive actions.

For each action, I’ve linked to a long, dry post with full sources. All the nuances and caveats and scientific arguments and many, many numbers are packed into those posts, to keep this one readable.

Right — enough burbling. Let’s go!

Recycling

In theory, if you recycled everything you could possibly recycle and you were separating paper, metal, plastics, glass, etc., into different bins and the recycling process was the best possible, you’d cool the Little Planet by about 0.01 °C in 2100. (0.012 °C for the US, 0.007 °C for the UK.)

That’s one-hundredth of a degree, not one-tenth. It’s about the warming produced by travelling from New York to Detroit and back once a year on a train. A major reason why recycling has such a tiny impact on emissions is that processing recycling is itself an energy-intensive process.

In practice recycling doesn’t even save that 0.01 °C:

  • A lot of recycling is mixed, and separating paper, plastics, etc., takes even more energy.
  • Even after separation, not everything is recycled; due to contamination and other factors, a lot goes to landfill or incineration.

As a result, the effect of recycling on climate change is miniscule. Trying to slow climate change by recycling is like trying to lose weight by cutting your hair. Depressingly, recycling is the most common action people cite when surveyed about climate change.

Plastics recycling needs a special shout-out. As the charts below shows, most plastic recycling is exported to countries with bad waste management practices, where it will end up incinerated on open rubbish dumps, releasing toxic fumes, or dumped into the ocean.

tl;dr: Recycling doesn’t make a dent in climate change. Recycled plastics are often actively harmful, poisoning people or ending up in the sea.

Sources, and a shorter discussion of plastic bags here.

Travel

On average, each person in the US or UK flies about 5,500km each year, which gets you from New York to London. Cutting out those flights (in economy class) would cool the Little Planet by 0.11 °C in 2100.

That ‘on average’ is pretty misleading, though. About half of those people don’t fly at all. So the ones that do fly must fly twice the distance — 11,000 km, or London to New York and back again each year. Cutting that trip out would cool their Little Planets by 0.22 °C in 2100. That’s for economy, by the way; the figure for business class is 0.60 °C.

If you fly more, the rule is that flying 5,000 km/3,000 miles each year warms the Little Planet by 0.1 °C in 2100. So 10,000 km/6,000 miles each year is 0.2 °C, and so on.

Incidentally, the carbon offsetting schemes sold by major airlines don’t do what they claim to and won’t make much difference to emissions.

What about driving? The average person in the US drives about 20 miles a day in a car that does 25 MPG. (That’s as a driver, not a passenger.) That ends up warming the Little Planet by about 0.50 °C in 2100. That’s very dependent on car size and fuel efficiency, though; driving the same distance in a SUV causes about 1.00 °C of warming.

You emissions will also be proportional to the distance you drive. If you drive 40 miles a day in an average US car, that’ll cause about 1.00 °C of warming; if you drive 10 miles a day in an average US car, that’ll cause about 0.25 °C of warming. Cutting out 4 miles a day, or 20% of your distance driven, reduces warming by 0.10 °C.

If you switch to an electric car, you can roughly halve those figures; for an average person that reduces warming by 0.25 °C. You have to be a little careful, though, because a surprising amount of the warming figures I’ve given come not from burning petrol but from making cars; manufacturing just one typical US car might cause 0.05 °C of warming, or slightly more for an electric car. So if you want to minimise emissions, you should wait until your previous car is unusable before buying an electric car.

All the warming numbers for the UK are about half those for the US because cars are smaller and people drive less.

Sources for flying here and driving here.

Food

There’s not really a polite way to say this...

Cows and sheep burp.

They burp methane, which causes far more warming than carbon dioxide. Methane breaks down into carbon dioxide over time, but even by 2100 a ton of methane will have caused at least 10x the warming of a ton of carbon dioxide.

This means that the beef, lamb and dairy products that come from cows and sheep account for a large chunk of the embedded emissions in western diets. Other meat contributes a little as well, as you can see here:

All of this means that someone in the US or UK can reduce their emissions by going vegetarian or going vegan. The figures for the two countries aren’t that different:

  • Going vegetarian cools the Little Planet by about 0.12 °C in 2100.
  • Going vegan instead cools it by about 0.15 °C in 2100.

Most of that 0.12 °C from going vegetarian comes from giving up beef and lamb; other meats have a much smaller effect. You can also reduce emissions a noticeable amount by avoiding air-freighted food.

Sources.

I’m nervous writing about the next topic. Research suggests that when people feel climate change science is critical of their choices, they reach by attacking the science or attacking scientists’ own lifestyles.

Please don’t.

38% of young Americans think that ‘climate change should be a factor in a couple’s decision about whether to have children’. If you share that belief, this next section has numbers you might find useful. If not, I’d skip ahead. If you already have children, I’d skip ahead; this article is about choices going forwards, not blame or guilt.

Children

For an average person in the US, having one child increases the Little Planet’s 2100 temperature by 2.2 °C. The figure for the UK is 1.4°C. Figures for all developed countries are in the same range; those for developing countries are much lower.

(Those figures assume your child is splitting their time between your Little Planet and another parent’s Little Planet. If you’re choosing to have a child on your own, please double them.)

If you’ve been following the numbers so far, you’ll have noticed that these figures are much larger than any others we’ve seen: little people have a startling effect on a Little Planet. For an average person in the US, having one less child has about five times as much effect as giving up driving completely. One professor of climate science puts it starkly:

Unless you will ever contemplate lighting a forest fire, the decision to reproduce is probably the biggest carbon choice you will ever make.

It is deeply sad that something so natural and essentially human has so much impact on climate change. If you take away one idea from this article, it should be that climate science is indifferent to our sense of what is good and bad. Recycling feels so rewarding and green, but has no impact on warming. Having children…

Well, I think I’ve said enough.

You might hope that if you raise your children to be environmentally conscious, they’ll have a much lower impact. The research stabs us again here:

  • ‘Tolerable’ lifestyle changes can only give a 30% reduction in energy use and emissions.
  • People can be pretty effective at teaching children to recycle, which has about as much effect on warming as singing Kumbaya. But there’s almost no correlation between parents’ energy use and their children’s, even before they leave home. So you’re unlikely to get near to that 30% reduction.

None of that means that how you bring up your children doesn’t affect warming. If you managed to reduce the emissions from having one child by 10%, that’s 0.22 °C for the US, or about as much as you’d save by switching to an electric car. Having a child causes so much warming that even saving 10% is a big effect.

Writing this section has made me melancholy. If reading it has had the same effect on you, I am really sorry. There is some upbeat news, though: those numbers mean that supporting family planning and women’s education can have a huge impact on climate change, far more than e.g. planting trees.

Sources and more. This covers the research and the many misunderstandings of it in the media. It may be less dry than the other sources links, but be warned, it’s long!

Home Energy Use

We’ve now talked about nearly all the actions that people list when asked about slowing climate change. There’s one more that’s generally missed, which is to reduce home gas and electricity use. There are a couple of easy things that can be done here, such as hanging up clothes to dry rather than using dryers, but to really make a dent you need to install heat pumps and improve insulation.

I’m not providing numbers here because they vary a lot depending on where exactly you live. But very, very roughly speaking, concerted action here is probably comparable to switching to an electric car.

Summary

Here’s a summary of all the numbers we’ve found so far.

All of these are for the average person; the sections above tell you how to adapt them to your own situation. Also, please don’t take these numbers to be too exact; climate science involves a lot of estimates. What you should take away from this is:

Recycling has a negligible effect on the Little Planet. Driving, flying and diet have significant effects. How many children you choose to have has a much larger effect than anything else.

Please don’t fixate on the part about children if it raises strong feelings. For the average person in either country, changes to driving, flying and diet can reduce warming by about 0.5 °C.

Half a degree less warming is a big deal. Some people claim that individual actions can’t impact warming that much. There’s no research behind that claim, and our numbers show it’s just plain wrong.

Key science, with sources. Minus bad statistics. Minus shaky methodology. Minus politicisation, left or right.

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