Steel slag captures carbon from the atmosphere. Companies with climate goals — and an Ohio motocross raceway — are making use of it.

In this week’s “Make Me Smart” newsletter, we explain the latest moves to establish a credible global market for carbon credits. Plus, we do the numbers on open enrollment and the rising cost of health care.

A growing number of scientists and economists see a novel kind of credit as an important tool to help reverse global declines in biodiversity.

If you can’t pollute less, pay someone else to pollute less for you. Carbon offsets sound simple but are complicated in practice.