In contrast with a strengthening consensus among Iowa scientists, the states political leaders remain divided along party lines about the role of human activity in climate change.

Iowas climate will likely continue to warm due to increasing emissions of heat-trapping gases, said this years Iowa Climate Statement, signed by 155 Iowa scientists, up sharply from the 44 who signed the 2011 statement.

Chris Anderson, assistant director of the Iowa State University Climate Science Program and a co-author of the Oct. 18 statement, said he hopes the mounting support reflects the increasing body of evidence, the authors Iowa focus and their intent to be honest brokers.

Among Iowa politicians, Democrats almost unanimously agree that the burning of fossil fuels is causing or accelerating harmful climate changes, while Republicans tend to believe that such changes may well be manifestations of natural cycles.

Democrats say that disagreement has impeded progress on measures that would encourage energy conservation and development of renewable energy, in effect leaving more fossil fuels in the ground.

They also say Republicans are dragging their feet on efforts to make Iowa less vulnerable to future floods.

State Sen. Rob Hogg, D-Cedar Rapids, perhaps the states leading advocate of curbing greenhouse gases, cited several examples of Democratic initiatives that failed to be taken up in the Republican-controlled House.

Among them are a state wind energy development tax credit, charging and refueling stations for vehicles powered by electricity and natural gas, and a commitment to expanding passenger rail transportation.

State Rep. Mary Mascher, D-Iowa City, who accepts the scientific consensus on climate change, said she is frustrated with the states limited commitment to countering flooding by improving the absorbency of watersheds through expanded conservation practices.

Asserting that the voluntary approach at the heart of the states Nutrient Reduction Strategy will take too long to work, Mascher said Democrats are pushing for legislation that would require more conservation practices.

While Gov. Terry Branstads office did not respond to a request for an updated position statement, the governor expressed his view of climate change during a January meeting with The Gazettes editorial board.

People tend to project whats happening into the future, but I guess I dont necessarily buy that," he said.

Were in a cycle right now where were experiencing warming, but weve also throughout history seen times when its gone the other way and its gotten colder, he said.

In a 2010 Gazette interview, Branstad said that, "We have to recognize that weather patterns go through cycles. We are in a wetter cycle right now, but these things change. You have to deal with it as it comes.

Department of Natural Resources Director Chuck Gipp, a Republican who formerly served as speaker of the Iowa House, declined to say whether he believes the burning of carbon-based fuels is causing climate change.

Our climate has always changed, and it continues to change. How we react to those changes is more important than wasting energy debating causes, Gipp said.

No one knows whether todays changes will be short-term and cyclical or long-term and lasting, he said.

In the meantime, Gipp said it is important to respond to the states most pressing climate change threats  most notably, the extreme rainfall events that have caused billions of dollars damage in Iowa during the 21st century..

Iowa Agriculture Secretary Bill Northey, a Republican who is frequently mentioned as a candidate for higher office, said he has no idea whats causing climate change.

I see dueling studies, dueling scientists discussing the issue, but Iowa farmers have always faced variable weather conditions, he said.

Whatever the cause, we have to be able to manage what comes, Northey said.

Hogg, the author of a recent book on climate change, Americas Climate Century, said climate change is real and it is contributing to more extreme weather events like floods, droughts and wildfires, and more ecological disruptions like the decline of Iowa's pheasant population.

State Sen. Joe Bolkcom, D-Iowa City, said the vast majority of scientists worldwide have established that humans burning fossil fuels have dramatically increased heat trapping gases that are causing our planet to warm.

Climate change and disruption caused in part by human activities is settled science, according to State Sen. Robert Dvorsky, D-Coralville.

State Sen. Liz Mathis, D-Robins, based on her own observations and the credible statements of Iowa scientists, said she believes the burning of fossil fuels contributes to the increasingly extreme weather Iowans have experienced in recent years.

The burning of fossil fuels is releasing greenhouse gases that are causing atmospheric temperatures to rise, said State Rep. Art Staed, D-Cedar Rapids.

State Rep. Kirsten Running-Marquardt, D-Cedar Rapids, said she has been a strong supporter of renewable energy in part because of her belief that burning fossil fuels contributes to climate change.

I agree with Sen. Hogg, said State Rep. Dave Jacoby, D-Coralville.

Iowas representatives in the U.S. House declared their positions on climate change with their 2009 votes on the American Clean Energy and Security Act, which would have established a cap and trade approach to curbing the heat-trapping gases scientists have linked to climate change.

The measure, which passed in the House but died of inaction in the Senate, would have limited greenhouse gas emissions by requiring polluters to receive or buy emission permits, with the number of available permits gradually falling over time.

Rep. Dave Loebsack, a Democrat representing Iowas 2nd District, and Rep. Bruce Braley, a Democrat representing Iowas 1st District, voted for it, while Republican Reps. Tom Latham and Steve King, voted against it.

Hogg said the partisan divide is hard to understand. Science is nonpartisan. Climate is nonpartisan. Property damage is nonpartisan, he said.

Republicans may have been slower to accept scientists climate change pronouncements, he said, in part because of fear they would be challenged on them in primary elections.

Hogg said a major departure occurred in August when four former Environmental Protection Agency chiefs under Republican administrations, William Ruckelshaus, Lee Thomas, William Reilly and Christine Todd Whitman, called for continued efforts to reduce the climate-altering pollutants that threaten our planet.There is no longer any credible scientific debate about the basic facts, the former EPA administrators wrote in an Aug. 1 New York Times opinion piece.