For nearly a quarter of a century, the United Nations has released periodic reports collating thousands of scientists’ assessments of climate change. The bottom line: the accumulation of greenhouse gas emissions from the human enterprise constitute a threat to the planet. That makes climate change the most urgent, consequential, dangerous, and difficult challenge of our time. Arguably, it fits that billing for any time. The only other case of humanity threatening its own survival is the specter of global thermonuclear war, which is easier to deal with: avoiding World War III is a matter of leaders’ not doing something—pressing the buttons that launch the missiles. Keeping climate change at bay is a matter of taking action on numerous fronts and doing so seriously, massively, effectively, and soon.

Patricia Mulroy has been called “the water empress of Vegas.” For 25 years, she lead the Southern Nevada Water Authority, the agency responsible for keeping the taps running in a desert metropolis that was growing like the fat guy in the Monty Python skit. As I wrote yesterday, she was a force to be reckoned with.