State climatologist addresses climate change to water board

“I’m pretty close to calling myself a converted skeptic”

When state climatologist Nolan Doesken met with the Upper Gunnison River Conservancy District Monday, April 27, he got the question every scientist in his field has heard, or at least considered, in the last few years.

“So you’re the guy. Tell me about global warming,” said board member Bill Nesbitt. “You have the connections, is it real or not real?”
The question had Doesken squirming in his seat, until he stood up and it all came out.
“I can’t give you a short story. I can give you my story,” said Doesken.
He said that like many climatologists rooted in agriculture, he has been skeptical throughout the debate. But as he sees more information, the evidence is mounting in favor of long-term temperature increase.
“There is no doubt that carbon dioxide, CO2, in the atmosphere is increasing and that models of the atmospheric processes, which are pretty good models, show that when you add more CO2 in the atmosphere, more energy comes in and is trapped than what went out when there was less CO2. It’s a greenhouse gas,” he said.
He continued, “CO2 apparently will continue to go up and hardly anybody disagrees that the CO2 increase is at least to a large extent the result of our human thirst for energy.”
Doesken explained that greenhouse gases in the earth’s atmosphere are transparent to incoming solar radiation, but absorb outgoing long wave thermal energy, or heat. He also said there was no doubt that concentrations of those gases are increasing in the atmosphere.
“This is sort of our big experiment this year, because nothing we’ve done has been able to decrease the amount of carbon dioxide. Theoretically slowing down the global economy should slow down the output of CO2… But CO2 continues to increase this year, I just got the results and [CO2] is going up at the same rate as it was before the global recession,” said Doesken.
Carbon dioxide alone, however, isn’t going to account for too much of a temperature increase. Although it’s a good greenhouse gas, methane traps more than 20 times as much heat as CO2 and methane levels in the atmosphere have been staying steady.
“The big unknown is a natural greenhouse gas and that’s water vapor. Water vapor in the gaseous form, not as clouds, is likewise transparent to incoming solar radiation and is very good at absorbing long wave radiation as it goes out,” he said.
A real world example of the heat trapping effect of water vapor can be seen in arid climates, where it often cools down considerably after the sun goes down. The more humid the atmosphere, the more stable the temperature.
“So the big question is what happens to water vapor?” asked Doesken. “If you get more moist cool air, then you get warmer and if you get big thick clouds then you get cooler. It’s a big balancing act,” he said.
Reaching his answer to the question, Doesken said, “where I’ve come down on this is I’m pretty close to calling myself a converted skeptic at this point. I’m thinking that it’s something that is real enough that I’m really concerned about it.
“Variability happens. You had a heck of a winter here a year ago and it reminded you that yes you can still have an old fashioned winter. But warming winters have outnumbered cooler ones by a whole lot.”