Cool! The president’s top scientist is taking questions on Twitter? Which one? Bill Nye the Science Guy or Neil deGrasse Tyson?

Neither? Oh man, it’s going to be famed oceanographer John Kerry, isn’t it? Or maybe infectious diseases expert Ron Klain?

Thanks for that kind invitation. We’d forgotten about Dr. John P. Holdren, Director of the White House Office of Science and Technology Policy. Anyone who does have questions about climate change can ask Dr. Holdren via the hashtag #AshDrH. Who wants to start?

Hey, that’s from a 30-year-old textbook co-written with two other people. Blame them.

One final question please, before we wrap this up.