Mini Planet: The United States and China just announced that they will formally join the Paris climate agreement. The worlds top two contributors to global warming account for 37.98 percent of global greenhouse gas emissions (17.89 percent US, 20.09 percent China). The Paris climate deal needs to be ratified by 55 countries representing at least 55 percent of global emissions in order for the agreement to enter into force. The US and China announcement brings the total ratifications to 26 and total emissions...