What you can do about climate change

Global climate: it’s complicated. Any long-term solution will require profound changes in how we generate energy. At the same time, you can act to reduce your personal contribution to a warming planet. Here are seven simple guidelines on how your choices today affect the climate tomorrow.

Take the bus
To give ourselves a shot at avoiding effects like widespread flooding of coastal cities or collapse of the food supply, scientists have determined there’s only so much carbon dioxide we can safely emit. Divvying this up among the world’s population (and making some assumptions about future emissions) gives an average amount per person: an annual “carbon budget.”

The current per capita emissions for Americans is about 10 times this limit; given the relative affluence of this country, our emissions will not get down to the average anytime soon. But they can fall from where they are. Consider this: If you drive to work alone every day, your commuting alone eats up more than your entire carbon budget for the year. Taking the bus — or biking — would sharply reduce your output.

Eat everything in your refrigerator
Scientists have estimated that up to 40 per cent of American food is wasted — which amounts to almost 1,400 calories per person every day. Food waste occupies a significant chunk of our landfills, adding methane to the atmosphere as it decomposes.

Even more important, wasted food adds to the amount of food that needs to be produced, which is already a big part of our carbon load.

How can you waste less? For food shopping, plan out meals ahead of time, use a shopping list and avoid impulse buys. At home, freeze food before it spoils. If you find yourself routinely throwing prepared food away, reduce portion sizes.

Flying is bad; so is driving
Remember that annual carbon budget? One round-trip flight between New York and Los Angeles, and it’s all gone. Fliers can reduce their footprint somewhat by traveling coach. First-class seats take up more room, which means more flights for the same number of people. On average, a first-class seat is 2 1/2 times more detrimental to the environment than economy.

But driving can be even worse. A cross-country road trip creates more carbon emissions than a flight, per capita. A hybrid or electric car will save on gas, yet most electricity in this country still comes from fossil fuels.

Taking a train or a bus is best, especially for shorter trips. Or try the Internet: A Skype call or Google Hangout produces very little carbon dioxide.

Cats and dogs are ok
Every so often, a news outlet points to pet ownership as being bad for the climate. At first, the argument seems logical: Dogs and cats eat mostly meat, which is extremely carbon-intensive, so they must be driving carbon emissions.

But our pets generally aren’t munching prime cuts of steak; they’re eating the leftover parts that people don’t want. When a cow is slaughtered, almost 50 percent of it is unfit for human consumption. The meat that ends up in pet food is a byproduct of human meat consumption, not a driver of it.

If you do get a dog, you can use it to the climate’s advantage. A dog will help you get in the habit of taking walks. The next time you need to run a quick errand to a nearby store, you can walk rather than hopping in your car.

It’s better to eat produce from Spain than local beef
Eating local is lovely, but most carbon emissions involving food don’t come from transportation: They come from production, and the production of red meat and dairy is very carbon-intensive.

Emissions from red-meat production come from methane, a potent greenhouse gas. Experts disagree about how methane emissions should be counted in the planet’s emissions tally, but nearly everyone agrees that raising cattle and sheep causes warming far greater than that from producing alternate protein sources like chicken, fish and eggs.

According to researchers at Carnegie Mellon, a typical household that replaces 30 per cent of its calories from red meat and dairy with a combination of chicken, fish and eggs will save more carbon than a household that ate entirely local food for a full year.

Yes, eating nothing but locally grown produce would reduce your carbon footprint the most. But if you’re not ready to make that leap, reducing how much meat you eat matters more than going local.

Replace your gas guzzler if you want — but don’t buy a 2nd car
Before you even start driving that new car to add to your first one, you’ve already burned up 3 1/2 times your annual carbon budget. How? By encouraging the manufacturing of all of those raw materials and metals.

Yet there’s a break-even point at which the carbon savings from driving a new, more efficient car exceeds the carbon cost required to produce it. For example, on average, trading in a 15-mpg SUV for a 35-mpg sedan offsets the extra manufacturing costs within two years.

Anything you do to improve mileage will reduce your carbon output. Keeping to the speed limit and driving defensively can improve your mileage by more than 30 percent, according to the Department of Energy. Even something as simple as keeping your tires inflated and having your engine tuned up can give you up to a 7 percent bump in mpg — and an average carbon savings of about what you’d save from eating only local foods all year.

Buy less stuff, waste less stuff
It’s not just car manufacturing that adds to carbon emissions. Other consumer goods can have a huge impact: Making that new MacBook Pro burns the same amount of carbon as driving 1,300 miles from Denver to Cupertino, California, to pick it up in person.

At the other end of the product life cycle, reducing waste helps. Recycling is fine, but it’s better not to consume the raw materials in the first place, so you may want to think carefully before you buy.

Of course, these individual choices are all small measures.

A sustainable solution will require major changes in the global energy system: transitioning from fossil fuels to renewable energy and sharply reducing the number of cars running on internal-combustion engines.

Advocating public policies to support development of clean energy and efficient transportation is probably the most climate-friendly thing you can do. But cultural and behavioral change can be part of the solution, too. Might as well start now.