The article suggests a new way to encourage countries to reduce carbon emissions by identifying and penalizing those who are not doing their fair share. By looking at a country's carbon intensity, how quickly it's changing, and its GDP per person, we can figure out who's not pulling their weight. The researchers propose using trade sanctions to push these countries to cut emissions. They tested this idea with three different scenarios and found that some countries are taking advantage of the system by not reducing their emissions enough.