Turns out, global warming is caused my Mother Nature.
A new study finds that wildfire smoke caused up to half of all air pollution in the western U.S. in recent years.
Researchers at Stanford University and U-C San Diego learned that even as pollution emissions declined from other sources like vehicle exhaust and power plants, the amount from fires has increased.
The findings highlight the growing public health threat posed by climate change which has contributed to the devastating wildfires that scorched millions of acres in California and the Pacific Northwest last year.
A firefighter sprays water on a burning home as the Kincade Fire burns through the Jimtown community of unincorporated Sonoma County, Calif., on Thursday, Oct. 24, 2019. (AP Photo/Noah Berger)