The article compares carbon tax and cap-and-trade systems for reducing emissions and encouraging clean innovation. The researchers found that both systems help reduce pollution, but cap-and-trade is more effective at promoting clean innovation. Under a carbon tax, companies can lose money, while the impact of cap-and-trade on profits depends on the set emission limit. The study supports using cap-and-trade to combat climate change, but it's crucial to set appropriate emission limits and carbon prices for it to work efficiently. Ultimately, different pollution control goals require different carbon emission policies.