Alex Wagner focused on the causes behind more intense hurricanes last night.

"There is only been nine Category 3 or higher storms that have made landfall on Florida's West Coast since 1950. Six of those have been since the year 2000," she said, noting it was hard to blame any one factor.

"But it is clearly the case that climate change is making storms like this one stronger. Joining us now is Katherine Heyhoe, chief scientist at the Nature Conservancy, professor at Texas Tech university and author of this book, 'Saving Us: A Climate Scientist's Case for Hope and Healing in a Divided World.'

"For people who are climate skeptics, how do you explain the role of climate change in a year like this?

"The way I explain it is like this, we know that hurricanes are a natural phenomenon. Climate change is exacerbating them, making them worse, like putting them on steroids," Heyhoe said.

"We aren't seeing a change in the overall numbers of hurricanes, but when those hurricanes happen they are intensified faster. They're getting stronger, they are dumping a lot more rain on us and they are even moving more slowly. Climate change is truly loading the weather dies against us, putting us all at risk."

Heyhoe said the rapid intensification of Hurricane Ian can be attributed to climate change.

"That is something that we are seeing with warmer oceans. Climate change is being caused by digging up and burning coal and gas and oil, which produces heat-trapping gases that are building up in the atmosphere around the planet," she said.

"Over 90% of the extra heat that is being trapped by that blanket is going into the ocean where it is powering stronger storms and allowing those storms to ratchet up for more quickly than the tropical storms before."

Wagner talked about hurricanes now moving slower and asked about the connection with climate change.

"The data is showing that on average, storms are moving a bit more slowly," Heyhoe said.

"Even more important that we haven't touched on, the fact that warmer air holds more water vapor. When a storm comes along, as they always do, there is more water vapor for that storm to dump on us than it was 50 or hundred years ago. Although you mentioned that any given hurricane is not the result of climate change, we are able to put numbers on just how much worse climate change made a specific hurricane.

"With Hurricane Harvey, it is estimated that nearly 40% of the rain that fell during Harvey, and in some places it was over 50 inches of rain, could not have occurred if that same hurricane had happened 100 years ago, as it easily could have. It was estimated even worse that more areas flooded and more economic damage has occurred because you might be used to 20 inches or 30 inches and be prepared for that, but once you get into the 40 and 50-inch range, that's when the really devastating damages occur. That's where places get flooded that we're not expecting it.

"We can put very specific numbers on how much worse climate change makes a heat wave, a wildfire, and a hurricane."