To the editor:

While we are struggling to end the COVID-19 crisis, it seems unfair that we have to endure another worldwide crisis. However, we are beginning to experience the negative effects of climate change, and we desperately need to ramp up mitigation efforts. With present planning by governments around the world, the average surface temperature of the earth will continue to rise for perhaps 30 or 40 years or more. Hence, for young people, the time span required to control and reverse global warming will very likely continue through a very significant part of their expected lifetime.

An important indicator of climate change is the concentration of carbon dioxide in the atmosphere. For hundreds of thousands of years prior to the industrial revolution the carbon dioxide concentration in the atmosphere (as determined from ice-core samples) has varied between about 180 and 300 parts per million. However, the concentration is presently at 417 parts per million and steadily rising. The burning of fossil fuels (coal, oil, and gas) is producing the increasing concentration, and the result is a corresponding upward trajectory in the average surface temperature of the earth.

Achieving net-zero carbon dioxide emission implies reduction such that the amount of emission is equal to the amount that is absorbed, where absorption is primarily provided by the oceans and mature forests. However, if interpreted literally, use of the term net-zero is slightly confusing. To stop the rise in temperature and hopefully start a reversal, an additional requirement will be to remove the excess carbon dioxide that is presently building in the atmosphere. In other words, we will actually need net-negative carbon emission, or we must remove carbon dioxide from the air.

Several countries have built experimental facilities to extract carbon dioxide from the air and then deposit the carbon underground. But the amount that these plants can remove is minuscule compared to the 50 billion tons of carbon dioxide that is presently emitted each year. However, if we can reduce emissions to nearly net-zero, then the scaled up versions of these plants might provide the necessary additional reduction.

Electric energy production is responsible for only about 27% of the carbon emission, but if we can switch totally to the production of clean electric energy (using solar, wind, and nuclear generation), this green energy can than be applied to transportation and manufacturing.

An excellent source of basic information is provided by NASA on a website devoted to climate change and global warming.