WASHINGTON -- President Barack Obama told the nation's governors Monday night states producing oil, gas and coal need to recognize an international trend line toward renewable energy that will continue after his presidency.

Fostering economic growth and combating climate change are not "either-or" options, Obama said, speaking at the National Governors Association reception at the White House. "But I want to be honest with you: If those states with extractive industries are not currently preparing for the fact that the energy mix is going to continue to change over time, you're probably doing a disservice to your constituents," the president said.

The comments followed a question from Gov. Matt Mead, R-Wyoming, who raised concerns about the future of coal mining in his state. Obama took his final question of the evening from Alaska Gov. Bill Walker, who pressed for opening the Arctic National Wildlife Refuge to oil drilling, an effort met with predictable resistance.

Walker, an independent, said he will continue to work with the administration to help solve Alaska's problems, including a "$4 billion deficit with a $5.6 billion budget."

"We have an oil pipeline that's empty. I need to fill it up," Walker said to Obama at the dinner. "There's a lot of oil up there, and we're going to get it safely. And thank you for some of your positions you've taken, but we need to put oil in that pipeline. We need access to 1 percent of our national park to be able to do that," Walker said, referring to the 10-02 section of ANWR. Drilling there requires congressional approval -- and a presidential signature -- that has been elusive in recent decades.

"We have encouraged exploration in some areas. There are some areas that are just real sensitive," Obama said in response. Alaskans are often of "two minds" about the issue, he said -- wanting to encourage drilling and also to preserve scenic areas.

"And our goal has been to try to balance those equities and to make sure that economic development has taken place in Alaska, that folks are being well served, but that we're also preserving the very thing that makes that place so unique and people care about it so deeply," Obama said.

Later in the program, the president noted that the federal government should be helping fossil-fuel states "maximize your production, minimizing your pollution, but also preparing you for the fact that 20, 30 years from now, there's going to be a higher mix of clean energy and a lower mix of traditional fossil fuels. That is almost inevitable," he said.

Even if the next president disagrees, "it's still going to happen, just because of the trend lines internationally. And we should prepare ourselves for that," Obama said.

Walker did not limit his comments to energy production. He noted he would continue to work with the Obama administration on Medicaid expansion and thanked Obama for his "unprecedented" recent trip to the state.

"What you did with rural Alaska, we've never seen before. You brought a hope and excitement there," Walker said.

Obama called Walker's "hospitality" during his trip "extraordinary" and recommended that everyone in the room visit. "It fills up your soul being up there, just the landscape and the expanse. The sheer scale of everything is remarkable, and the people could not have been more gracious and wonderful," Obama said.