VOA常速英语:气候变化使美国西部的野火火势严峻

As record-breaking fires burn across the western United States, president Donald Trump remains skeptical that climate change is a factor. Here he is Monday at a meeting with California officials. It'll start getting cooler, you just watch. I wish science agreed with you. Oh well I don't think science knows actually. Yet science has been sounding the alarm about climate change for a long time, says University of California Merced wildfire expert Leroy Westerling. We've been doing modeling and simulation for years now, that indicates that these really severe widespread fire seasons are coming. And we're seeing that emerge in real time. Wildfires need dry plants to burn. And climate change is increasing the supply he says. Studies show the west has warmed over the last century and warmer air dries things faster. That means even a normal year would be drier. But these have not been normal years he says. We had a drought for five years earlier in the 21st century here, that was uNPRecedented in probably the last thousand to twelve hundred years at least.

And warmer weather is melting the west's water reserves in the mountains. The region relies on winter snow accumulation to provide long-lasting water supplies, says wildfire expert Jessica Holovsky with the US Forest Service. We're seeing more precipitation falling as rain rather than snow. The snowpack isn't lasting as long with the higher temperatures. So it's running off earlier in the season. Leaving less water when the dry summer months arrive. And warmer drier conditions have helped tree-killing beetles multiply. All this has left roughly 150 million dead flammable trees standing in California's forests alone. But Hollowski says humans share the blame for the fires. Smaller fires used to happen naturally, which thinned out the forests. We have suppressed fire very effectively since world war II, that means there are more fuels now than there used to be. And so when fires do occur, there's more fuel to burn and they're more severe. Plus more people are living in areas that are prone to burn. So when fires do break out, they're more destructive and more costly. Conditions will get worse as the planet continues to warm Hollowski says. There's going to be more fire. You know, a kind of ballpark is maybe two to three times the annual area burned in the future. Scientists say this year's record-breaking fire season is just a taste of what's to come. Steve Baragona VOA news