Every summer, Brian Greenspun turns over his Where I Stand column to guest writers for several weeks. Today’s writer is U.S. Senate Majority Leader Harry Reid.

As I spent time with my grandchildren a few Saturdays ago, I couldn’t help but notice the looming clouds rising over Las Vegas. Only these clouds didn’t represent a 30-second, midsummer downpour. These clouds were smoke. Mount Charleston was burning. In fact, much of the West was burning. It would be days before the Carpenter 1 Fire, as it was called, was contained. In the meantime, more than 500 people were forced to evacuate their homes; 28,000 acres were burned; and at its peak, 1,300 firefighters worked around the clock to contain the blaze at the cost of $20 million. There should be no doubt: Climate change is contributing to wildfires in the West and causing them to be more ferocious, frequent and devastating.

As the Mount Charleston fire raged on and ash fell from the sky in Las Vegas, another wildfire was burning in Douglas County. The Bison Fire south of Reno was the largest blaze ever recorded in western Nevada. And while well-established science indicates that small, normally occurring wildfires are part of the healthy life cycle of forests, these types of large, catastrophic fires can cause extreme and long-lasting damage.

Not every wildfire, flood or drought can be attributed to human-induced transformation of our planet’s weather patterns, but in 2010, the National Research Council concluded that the average fire season has expanded by two and a half months. Nevada’s Desert Research Institute reports that over the past decade and a half, seven of the 11 Western contiguous states have seen the largest fire in their state’s recorded history, and some of these states have broken such records only to see them broken again in the following years.

The summers aren’t just getting longer; average temperatures are also rising, and higher temperatures mean more evaporation and less water. In the winter of 2005, we received an average amount of rain, but the high temperatures that year meant that the flows in the Colorado River were 25 percent lower than average. In areas prone to less rainfall, evaporation and transpiration of what little water exists creates drier plant life. This only exacerbates conditions conducive to fires. These drought-stressed trees and brush flare up faster than a healthy forest would, so fires get bigger and burn hotter once started.

It’s not just in the Western United States where fires are burning. In fact, the National Academy of Sciences — conceived by Congress during President Abraham Lincoln’s administration — has just published a study showing there are more fires burning now in the forests of Alaska than at any other time in the past 10,000 years. Think about that. In 10,000 years, they haven’t found a time when there were more fires in Alaska than there are right now.

On Tuesday, I will co-host the sixth annual National Clean Energy Summit with the Center for American Progress, the Clean Energy Project, MGM Resorts International and UNLV. One of the issues we will discuss is extreme weather and how clean energy investments can make communities more resilient to such weather. On this topic, we will hear from John Podesta of the Center for American Progress; Maria LaRosa, a meteorologist with the Weather Channel; Pat Mulroy of the Southern Nevada Water Authority; Dr. Kathryn Sullivan, an astronaut and acting administrator of the National Oceans and Atmospheric Administration; and Chris Taylor, with the West Coast Infrastructure Exchange. If you are interested in attending, please visit www.cleanenergysummit.org to sign up.

The danger of climate change isn’t limited to Nevada. At last year’s summit, I spoke at length about the other unparalleled extreme weather events taking place in the United States and in other parts of the globe. In 2012, the Midwest experienced its most crushing drought in more than half a century — and maybe ever. Also last year, devastating fires swept New Mexico, Idaho, Colorado and other parts of the Mountain West, destroying hundreds of homes and burning millions of trees. The East Coast experienced extreme thunderstorms and the Mississippi River was historically low.

Unfortunately, too many elected officials in Washington still talk about climate change as if it doesn’t exist. They falsely claim scientists are still debating whether carbon pollution is warming the planet. It’s time for us all — whether we’re leaders in Washington, members of the media, scientists, academics, environmentalists or utility industry executives — to stop acting like those who deny this crisis exists have a valid point of view. They don’t. Virtually every respected climate scientist in the world agrees the problem is real, and the time to act is now. Not tomorrow. Not a week from now. Not next month or next year. We must act today.

Sen. Harry Reid, a Democrat from Nevada, is the majority leader of the U.S. Senate.