Millions of residents of Southern California remain under flood advisories today after some areas received a month’s worth of precipitation in less than an hour, in what meteorologists called a once-in-a-millennium rainfall event. This comes as forecasters are predicting a snowless Christmas holiday for parts of Canada and much of the U.S. East Coast and Midwest, with rain and record highs forecast in Chicago and Minneapolis. This month, climate scientists confirmed 2023 will officially be the hottest year on record, with carbon dioxide levels in Earth’s atmosphere at their highest level in about 14 million years.