How can an individual help fight climate change?

Climate change can seem like such an enormous problem that individual actions would have little impact. Consider Europe’s wideranging proposals last week to reduce its reliance on fossil fuels, including eliminating sales of new gas- and diesel-powered cars in the next 14 years.

But people can have an impact, experts say, both by how they spend their money and how they spend their time.

Mary Weathers Case, for instance, chose to offset the carbon cost of a cross-country plane trip for her family through the site Gold Standard. Case, a psychiatrist who lives in South Salem, N.Y., with her husband and two children, said she had been reading and watching more news about climate change during the pandemic and had been motivated to do her part after hearing about the searing temperatures in the West.

What surprised her, though, was that after spending $3,000 on plane tickets to Portland, Ore., she could offset that carbon for $150.

“I was surprised that it was so cheap,” Case said.

Buying carbon offsets for a plane trip is one way to reduce your environmental impact. But people can allocate their money in other ways, both big and small, that reduce their contribution to climate change. Take how you invest.

With certain investments — namely, those that reduce or remove carbon from the atmosphere — there are defined ways to measure their environmental impact. With others, like water conservation, the metrics are not as clear because there is not an agreed-upon unit to measure.

“The improvement in measurement is growing by leaps and bounds,” said Sir Ronald Cohen, an early venture capitalist and the author of the book “Impact: Reshaping Capitalism to Drive Real Change.”

He advocates using what are called impact-weighted accounts, an initiative led by Harvard Business School, to evaluate a company’s positive and negative impact on the environment. By this measure, he has written, airlines like Lufthansa and American Airlines have an environmental impact that makes both companies unprofitable.

Yet he is also open to a less-bad approach. People invested in fossil fuel companies should consider that Exxon Mobil caused $39 billion in environmental damage from its carbon impact, according to Harvard Business School estimates, while BP caused $14 billion in damage. It is like deciding which energy bar is better for you to eat: Those that have less sugar have a better health impact.

“It’s where the world is heading,” Ronald said. “You can buy the products of the company whose values you share.”

Individuals can make other environmentally conscious choices as well, beyond carbon offsets or investing in cleaner energy.

Paul Greenberg, whose new book is “The Climate Diet: 50 Simple Ways to Trim Your Carbon Diet,” said continuing to work from home at least a few days a week was one significant way to reduce the carbon emissions from driving a car. But such decisions are not always so straightforward.

Take buying clothes. A shirt made with a synthetic material, like polyester, which is derived from petrochemicals, is more carbon-intensive than a cotton shirt. But that cotton shirt requires huge amounts of water to produce — more water than a person drinks in a year, Greenberg’s research found. His recommendation? Consider buying used clothing.

Some choices are harder than others. Dogs and cats may be beloved companions, but they are carnivores that are bad for the environment. “If you had a choice between a carnivorous dog and a

guinea pig that eats seeds,” Greenberg said, “go with the guinea pig.”

The real beasts, though, are free-standing homes. To reduce their carbon footprint, people can look for electricity providers that get their power from solar and wind. Once the electricity coming into the home is clean, Greenberg said, people can switch to electric appliances. He replaced his gas stove with an electric induction stove.

Solar panels have grown in popularity as their costs have fallen and their efficiency has increased. Milton Ross, who has owned a brownstone in Brooklyn’s Park Slope neighborhood since 1979, no longer has an electric bill because of the panels he had installed on his roof.

“My system back in 2015 was around $30,000,” Ross said. “My neighbors don’t do it because of the cost. I used my home equity line of credit, and I could claim the interest as a tax deduction. It just made sense to me. Meanwhile, everything is all paid back, and I don’t have an electric bill anymore.”

He has also replaced two gas-fired water heaters with an electric heat pump water heater, which cost him several thousand dollars to buy and have installed. “These things pay for themselves down the road,” he said.

Brooklyn Solar Works, which installed Ross’ array, said it had put in place more than 1,000 sets of solar panels in New York City. On average, federal, state and city incentives cover about 60% of the cost, which ranges from $28,000 to $40,000. For most homes, the remaining amount is paid off in electricity savings over about eight years, said T.R. Ludwig, the company’s founder.

He said most of his company’s systems offset about 10,000 pounds of carbon each year and produce about 7,000 kilowatt-hours of electricity, about one-quarter of what a family of four would use in a year.

Greenberg said some things mattered more than others. Using paper straws and LED light bulbs is not a huge way to reduce your carbon footprint. But steering clear of bottled water does help, since it takes 17 million barrels of oil to produce the world’s plastic water bottles each year.

“It’s always good to do something rather than nothing,” he said. “The problem is, sometimes we’re doing a lot of self-soothing when we buy some LED light bulbs. The real beast in our home lies beyond light bulbs.”

Case said she would feel better when she and her family moved to Brooklyn this summer and got rid of one car and started walking more in their neighborhood. She is also committed to buying things locally and not ordering them online.

“A lot of people tell me it doesn’t matter, that it’s too late,” she said. “That might be true. But I still think there’s value to doing the right thing.”