U.S. Rep. Dana Rohrabacher's continuous rejection of the science of human-caused climate change puts our economy, national security and children at risk. If he does not change his position, it is time for the voters of his district to replace him.

This week the U.S. Global Change Research Program released its 2014 National Climate Assessment. It reinforces what 97% of all climate scientists and more than 200 national science academies across the world say: The burning of fossil fuels is changing the earth's climate, and already the effects are being felt in the United States.

Climate change increases the threat of extreme rain, drought and fire events, and scientists say these events will increase in frequency and intensity if we do nothing to curb our carbon emissions. The United States has already seen an increase in extreme weather events, and droughts have caused billions of dollars in crop losses.

In March, the Department of Defense released its 2014 quadrennial review. It cites climate change as one of the primary global dynamics of the 21st century and links it to our national security, water, food, energy and economic security.

Tom Ridge, former secretary of Homeland Security under George W. Bush, told Pennsylvania's The Patriot-News last year, "The U.S. national security community, including leaders from the military, Homeland Security, and intelligence, understand that climate change is a national security threat. They're not talking about whether or not it is occurring – it is. They're talking about addressing the problem and protecting the American people. It's time Washington does the same."

We are the first generation to know that the burning of fossil fuels causes climate change and to see its effects. We are also the last generation able to head off the most severe consequences of climate change for our kids and future generations. Confronting climate change will strengthen our national security, our economy and our health. It will also show the world, once again, that the United States is willing to collectively rise up to any threat that confronts us.

Climate scientists have put us on notice. The next few years are crucial. We need policies that begin to significantly reduce our carbon emissions to avoid the worst risks that climate change will bring. It's the ultimate test of what America stands for.

As vice chair of the Committee on Science, Space and Technology, Rohrabacher's blatant disregard for the scientific evidence is alarming.

Voters in his district have a simple question to answer: Do they want Rohrabacher (R-Costa Mesa) to represent them in Congress when he believes human-caused climate change is "a fraud"?

TIM RECKMEYER lives in Minnesota, where he works as a technical account manager for Microsoft. The opinions expressed in this article are those of Mr. Reckmeyer and do not necessarily reflect the views of Microsoft or any of its affiliates.