I was really surprised to learn about the impact of denim. We often hear about the impact of agriculture on the environment, but we don’t usually hear those things about cotton. But cotton has an enormous impact: About 16 percent of all pesticides are used to grow cotton. And about 1 percent of the fresh water on earth is available (the rest is ice); of that 1 percent, about 70 percent is used for agriculture, and of that, about 3 percent is used for cotton.

To bring it down to some numbers we can understand: It takes on average 2,000 gallons of water to grow about two pounds of cotton. Turning cotton into a pair of jeans can use up to an additional 2,900 gallons of water. Cotton is also often grown in places where there isn’t a lot of water to begin with. We might not think that our lives have anything to do with water usage in Uzbekistan, for instance, but they do.

It’s really hard for the average consumer to know that, and I don’t think that it should be on each one of us to figure out which pair of jeans was produced with the least water. It should be up to companies to take more responsibility for the supply chain and adopt practices to dramatically reduce the amount of water they use. But we do have power as consumers: We don’t have to support companies that aren’t at the very least transparent about their practices.

I was constantly seeing articles about cardboard waste and people generally feeling guilty about ordering stuff online, so I wanted to find out whether it was as detrimental to the environment as I thought. It turns out that we actually don’t use much more cardboard than we used to. We use less cardboard than we did in 1999, largely because packaging is more efficient. That said, we’ve gotten worse at recycling it. Retailers (who used to handle much more cardboard) recycle about 90 to 100 percent of it. We, the consumers, recycle only about 25 percent.

I also wanted to know whether it was wasteful to order things online instead of going to get them from the store. For the most part, it’s not. Logistics companies like UPS and FedEx are much more efficient at planning their delivery routes than we are. They send trucks out to make stops on a route that uses the least amount of gas. We usually don’t do that. But we throw a wrench into that whole system when we select two-day shipping or next-day delivery. Since the delivery window is smaller, to make the delivery on time, a truck may have to go out less than full to get whatever it was I decided I needed as soon as possible. And when we order online, we return more. About 35 percent of what we buy online is returned, compared to around 10 percent of what we buy in a store—so that might mean a truck makes another trip to pick up our package.

It turns out the problem isn’t e-commerce necessarily. Rather, it’s that we want everything, and we want it all right now. Except when we return it. But in that case, we probably want something else instead.

Many of us probably don’t think of the internet as a physical system because we talk about it with words like “the cloud.” But it is actually a network of cables, routers, and modems all over the world, which require electricity to work—to store data and send it to each of us.

Streaming video, in particular, uses a lot of electricity for storage. And while it is more efficient to stream a video than to drive to a store and buy a DVD that was made from plastic and other materials, we watch much more video than we used to. So much so that we’ve basically canceled out all of those efficiency gains. For instance, in 2011 we watched about 3.2 billion hours of movies and TV online; in 2018, we watched 114 billion hours of video, including YouTube videos.

Those videos also may be stored on servers far from where we live, so when we watch a video at home, we might be creating a demand for electricity to be generated somewhere else. And depending on where that data center is, it might come from fossil fuels. (In the US, we still get about 25 percent of our electricity from coal.)

The main argument I try to make in the book is that we shouldn’t feel individually guilty about climate change and how our actions may be contributing to it. But we should feel collectively responsible for building a better world. The narrative of personal responsibility for climate change is problematic, because it lets those responsible off the hook. And there are people and corporations who are responsible, such as the climate change deniers in Congress and the fossil fuel companies, for the most part.

A lower-carbon or carbon-free world will be a better world, not only because it will help mitigate some of the worst effects of climate change, but because burning fossil fuels is bad for our health. It makes our air and water dirty, and it has a disproportionate impact on communities of color and low-income communities in this country. A lower-carbon society would be a more just society.

So how do we make that happen? Most importantly, we exercise our right to vote and get engaged in the political process. It’s critical that we elect leaders who are committed to climate action and that we understand whether their policies are sufficient and effective solutions. We don’t have to reelect them if they aren’t.

We also need to talk more about climate change. Most Americans don’t talk about climate change with their friends and family or hear about it in the media. But once they do, they are more likely to consider climate change a risk and to support policies to mitigate it. Once that happens, it’s important to get them to vote, too.

Lastly, we need to hold companies accountable, especially if our government won’t do it. We don’t have to support the companies that aren’t committed to sustainability or, at the very least, committed to making their practices transparent and then promising to improve.