[virtualdom]

You're right. There are two major errors in just this one paragraph from the article:

"Worldwide, humans use roughly one zettajoule per year. Satisfying that demand without further contributing to climate change means we’ll have to drastically speed up deployment of zero-carbon energy sources. Providing 1 ZJ per year with only solar PV, for example, would require covering roughly 1.6 percent of the world’s land area with panels."

Actually, humans used 162,494 TWh of primary energy in 2017, which is 585 petajoules (PJ). The authors admit to rounding up from roughly 600 PJ to 1000 PJ "for simplicity" later in the article. Rounding up by 66% is hardly appropriate for a back-of-napkin calculation, much less in a published article on a very serious topic.

Then, the authors imply that replacing all primary energy with solar power would require the same amount of primary energy. This is not true. If we were able to electrify all of humanities energy needs, we would only need 1/3 as much primary energy as we use today, since today's primary energy is mainly served by extremely inefficient fossil fuel combustion (coal and gas in power plants, petroleum for transport). 600 PJ is a reasonable estimate for primary energy use in 2021, so we would only need to build 200 PJ of solar power to replace fossil fuel combustion. The article called for 1000 PJ of solar, while reality is closer to 200 PJ. They were off by a factor of 5!

Obviously, this paragraph was an over-simplification and was meant as a thought experiment. But the sloppy rounding error and the lack of acknowledgment of the primary energy differences between solar power and fossil fuel combustion call into question how deeply the authors really understand the problem of climate change, and the solutions we have available.