North Alabama Congressman Mo Brooks' attempt to implicate falling rocks and erosion in rising sea levels dominated the national headlines, but there was more interesting news from last week's now-famous congressional hearing and those who took part.

For starters, none of the expert witnesses called by either Republicans or Democrats dispute that global warming is real. Or that humans caused it by burning fossil fuels. Or that humans can and need to do something about it.

"There was less disagreement than I expected," Dr. Philip Duffy said afterward. Duffy is the director of the Woods Hole Research Center who got into the much-viewed exchange with Brooks. Watch it below.

"Both of the Republican witnesses accept not only the reality of climate change, the human cause of climate change and the need to do something," Duffy said in an interview later. "They were prepared to have a conversation from that starting point. Unfortunately, it didn't work out that way."

Here are key points those witnesses made in their opening remarks.

"Mitigation as well as adaptation is an important part of addressing climate change," said Oren Cass of the Manhattan Institute. If the climate changes gradually, Cass said, "it will impose real costs which we can manage."

Cass also said that projecting the consequences of climate change without taking into account the possible responses by society isn't realistic. People can act and those actions will make a difference, he said.

Ted Nordhaus of the Breakthrough Institute said global warming is "a well-established scientific consensus." Temperatures are rising, Nordhaus agreed, and the increase is "caused in significant part by greenhouse gases caused by internal combustion engines" It's real, the source is human activity, and the "consequences are hard to quantify but could be catastrophic," he said.

"Climate change is a funny, funny problem," Duffy said in the interview several days after the hearing. "It's hard to wrap your mind around it."

There are a couple of reasons for that, Duffy said. First, an increase of 2 degrees in temperature doesn't sound so bad. It happens all the time outside. "But globally, it's very, very different," he said. "Globally, a 2-degree temperature increase really is a big, big deal and very, very unusual."

"That's hard to grasp," Duffy said. "And the urgency is hard to grasp."

Also, "normal" environmental problems often have a "point source" like a pollutant going into water. "If you shut off the pollutant," Duffy said, "the system cleans itself up quickly."

Climate change is different, he said. The main greenhouse gas, carbon dioxide, has a long life in the atmosphere. "We've done simulations that show if we were to totally and completely stop emitting greenhouse gases, which of course we're not going to do," Duffy said, "the temperature would not drop for hundreds of years. It's kind of locked in."

The other big deal is "global ice," Duffy said.

"Antarctica was discussed, and those ice sheets are shrinking," he said. "They're disintegrating and that disintegration is accelerating. And that drives sea level rise."

That melting land ice and the thermal expansion of sea water are the major causes of sea level rise, Duffy said. Thermal expansion means water expands or increases in volume as it heats up

What worries scientists like Duffy is if global warming increases enough to melt the ice covering most of Greenland. "If Greenland melts, that's like 23 feet of sea level rise," Duffy said. "Nobody thinks Greenland is going to melt in the next year or even in the next 10 years, or probably even in the next 100 years."

"But what might happen is we might cross the threshold where that becomes inevitable and unstoppable," Duffy said. "So that's another reason for the urgency. We don't want that to happen. We suspect we're pretty close to that threshold of warming already."

(Updated May 28, 2018 at 6:45 a.m. to correct the name of Dr. Duffy's research center, the Woods Hole Research Center.)