Jahren doesn't jump straight into talking about climate. She first looks at how a wide variety of statistics about our society and our world have changed over time, especially the last fifty years or so: life expectancy, percentage of population living in cities, crop and animal product yields, energy production and consumption... I think this may be a helpful way of starting the conversation with climate change skeptics. It's easier to believe unprecedented changes are about to happen when you contemplate how many unprecedented changes have very recently occurred.
When she does start discussing the danger we face, Jahren throws cold water on some sources of hope. Although the percentage of energy the world gets from renewable sources is trending up, the total demand for energy is increasing too; thus "the amount of fossil fuels burned each year has more than doubled over the last fifty years". And she argues this is not solvable by just investing more in renewable energy:
Switching whole-hog to renewable energy at today's level of electricity consumption is not possible for the United States, although I've heard people talk about it as if it were an attainable goal. ... we'd need a breakthrough that could improve the output of energy by an order of magnitude.
She sees nuclear energy as a more promising option for moving away from fossil fuels. But her larger plea is for us to consume less. She believes that although this would require significant changes to our lives, it would not "necessarily reduce our quality of life":
Life expectancy in Switzerland back in 1965 was similar to that of today's America ... Work days were shorter, as were commuting distances. Life was not perfect then, but the basics of a healthy life were already in place at a much lower level of fossil fuel use. ... In 2017, the Global Happiness Council ... reported that Americans were the unhappiest they had ever been - at least since 2005 - despite the fact that they were working, eating, driving, and consuming more than ever before.