Barack Obama

While nothing can fully replace the power of in-person diplomacy, remote meetings have an important role to play in tackling global challenges like climate change. They offer a way to maintain momentum on critical issues in between larger conferences and can reduce our own carbon footprint.

We have set a clear goal vital to the next chapter of America's story in space: sending humans to Mars by the 2030s and returning them safely to Earth, with the ultimate ambition to one day remain there for an extended time. The next step is to reach beyond the bounds of Earth's orbit. I'm excited about sending astronauts to Mars and believe it deserves bipartisan support in the coming years and decades.

I do not believe that governments should permit the creation of novel tropical islands through volcano geoengineering. The potential environmental risks and unintended consequences are too great, and we lack comprehensive understanding of the long-term impacts on our planet's ecosystems.