The article discusses a model that looks at how to reduce carbon emissions from burning fossil fuels. The researchers found that placing a tax on carbon can help decrease emissions in the short and long term, move us more quickly to using renewable energy sources, and encourage keeping more fossil fuels in the ground. They also discovered that offering incentives for renewables can lead to faster fossil fuel extraction at first, but it speeds up the shift to clean energy, preserves more fossil fuels, and helps limit cumulative carbon emissions and global warming. However, too much subsidy for renewables could end up costing more than it helps. The study shows that an optimal carbon tax is a better climate policy than large renewables subsidies.