Five things you can do to save the planet

Here's how family size, how you travel and what you eat affect your carbon emissions.

Trying to minimise your impact on the environment might seem complicated and puzzling. What matters more, buying eco lightbulbs or recycling? Your diet or the method of transport you use? To help, Swedish scientists at Lund University have come up with a simple list showing what things you can change to have the biggest positive impact on the environment.

Doing your bit for the environment can come in many forms: buying fewer plastic-wrapped products, using medicines and cleaning products that don't harm fish when flushed down the drains, or avoiding buying food (or even drugs) that involve destroying the Amazon rainforest.

But one of the most important ways is cutting your carbon emissions to slow climate change. The average person's carbon footprint in the UK is 10 tonnes a year.

1. Have fewer children

It might be a tough one to acknowledge, but the way to make the biggest single cut to your carbon emissions is to have fewer children. For every child you don't have, you save an average of 60 tonnes of carbon dioxide each year.

How did they get to these figures? It's not just about the direct carbon cost of child-rearing – the extra food, nappies and so on. The carbon emissions of the child and their descendants are factored into the equation too.

Exactly how much carbon this cuts off your budget varies depending on which country you're in. That figure is even higher in the US, at 120 tonnes of carbon a year. In Japan it's lower, at closer to 20 tonnes of carbon a year.

"A US family who chooses to have one fewer child would provide the same level of emissions reductions as 684 teenagers who choose to adopt comprehensive recycling for the rest of their lives," the authors write in their study, published in Environmental Research Letters.

Babies — Cute maybe, but having many children is the worst thing you could do for your carbon emissions. mulan

2. Get rid of your car

Living car-free is another way to make a big cut in carbon emissions. Electric cars are better than fossil-fuel-burning ones, but their electricity is still usually generated by burning fossil fuels. It just happens at a power plant rather than in the car's engine.

If you do have to use a car, make sure it's the most efficient one. Making sure your car is the most efficient with petrol or diesel can save more than a tonne of carbon a year. If you already have an electric car, going car-free can save about the same amount.

3. Avoid one transatlantic flight a year

The first entirely solar-powered plane, Solar Impulse 2, made a round-the-world trip last year. Aviation is set to be one of the last transport industries to switch over to low-carbon energy sources. One round-trip transatlantic flight has a carbon cost of about 1.6 tonnes. While long-haul flights are obviously the worst, reducing the amount of flying you do altogether can also have a large impact on your carbon footprint.

The Boeing 737 MAX family of aeroplanes — A round-trip transatlantic journey is one way to blow your sustainable carbon budget for almost the whole year. Boeing

4. Buy green energy

This means making sure the energy you use in your home comes from a renewable source and not fossil fuels. How much difference this makes again depends on exactly where you live.

How much should you aim to cut your emissions?

The average global carbon emissions will have to be cut to just 2.1 tonnes per person a year to keep the planet below 2C of global warming, the level agreed to in the Paris Agreement.

To put that in context: eating meat and taking just one round-trip transatlantic flight is enough to more than blow this budget for the year, without any further emissions in daily life.

In Australia, for example, switching to a green energy source has a much greater impact than in parts of Europe.

"In regions with carbon-based energy grids such as Australia and North America, green energy has the potential to greatly reduce emissions associated with home energy use," the authors wrote.

5. Eat more vegan and vegetarian food

Eating meat, poultry, fish, milk or eggs can add about a tonne of carbon to your budget each year. Vegetarian diets are also associated with a range of health benefits.

Some meats are worse than others. Beef has the biggest impact on the environment, using a great deal more land and carbon than crops. Cows also emit a lot of methane, which is a greenhouse gas contributing to climate change.

But make sure that the vegan food you go for isn't all imported from the other side of the world. If food has to be transported for thousands of miles by air or shipping then this racks up the carbon cost.

"Studies show we cannot expect to stay under a 2C [of global warming] limit without at least some shifts in diet," the authors write.