Most environmental scientists agree that human activity directly contributes to global warming. Luckily, most also agree that human activity also has the potential to reverse global warming. There are several changes that average Americans can make to lower their carbon footprints. The first change they can make is to reduce, reuse, and recycle as often as possible. A large amount of pollution is expelled in the production of new products; whereas, it requires no additional fossil fuels to reuse an item. Recycling, while still using fossil fuels to reprocess the product, consumes much less energy than creating a new item from scratch. Using public transportation is another way that Americans can reduce their carbon footprints. Cars are the single biggest contributor to greenhouse gases. Walking to work and school is even more beneficial. Lastly, more Americans can adopt alternative energy sources. Installing wind turbines and solar panels reduces our reliance on fossil fuels, which will reduce the harmful emissions they cause. By adopting all three of these changes, Americans can help ensure a brighter future for generations to come.

Look beyond the first sentence to identify the topic sentence?