We should welcome the fact that CO2 has risen to “levels not seen on Earth for millions of years,” even if the “fact” is less certain than you might believe. Plants have been trying to cope with a CO2 famine for millions of years, a famine that is finally ending. With self-assurance worthy of Dr. Pangloss, the article implies that pre-industrial CO2 levels, around 280 ppm, were the “best of all possible worlds.” But 280 ppm is much closer to (sea-level) starvation levels of about 150 ppm, when many plants die, than to the optimum levels for plant growth, which greenhouse operators already know are greater than 1000 ppm. There is fossil evidence of CO2 starvation at the end of the last ice age, when CO2 levels dropped to below 200 ppm. Even today’s 400 ppm is far too low for optimum plant growth.