This is how climate change contributed to the California wildfires

Climate change has played a major role in the unprecedented wildfires that are raging through Southern California.

Five wildfires -- the Palisades, Eaton, Hurst, Woodley and Lidia fires -- were burning through Ventura and Los Angeles counties on Wednesday. At least five people have been killed and several others injured by the disaster, according to officials.

While wildfires are a natural and necessary part of Earth's cycle, climate change and other more direct human influences have increased their likelihood. Climate change is making naturally occurring events more intense and more frequent, research shows.

In recent decades, wildfires in the western U.S. have become larger, more intense and more destructive due to a combination of factors, such as rapid urbanization and human-amplified climate change that "has produced warmer and drier conditions with prolonged droughts that stress forest vegetation facilitating pest outbreaks and tree death, leading to the accumulation of surface fuel," according to the federal government's Fifth National Climate Assessment, a breakdown of the latest in climate science coming from 14 different federal agencies, published in November 2023.

In addition, dry fuels for wildfires have been amplified in recent years by worsening extreme heat events and prolonged droughts, according to the Fifth National Climate Assessment. The increasing amount and flammability of dry vegetation is helping fuel more frequent large and destructive wildfires.

Warming temperatures, drier conditions and shifts in precipitation are contributing to an increase in the frequency of large wildfires and acres of land burned in the U.S. each year, according to the National Oceanic and Atmospheric Administration.

The U.S. wildfire season has grown longer and shifted earlier in recent decades due to warmer springs, longer summer dry seasons and drier vegetation, according to the Environmental Protection Agency.

About 85% of wildfires are started by humans, according to data from the U.S. Forest Service. Most are accidental, like an unattended campfire or sparks from a powerline. But this has been exacerbated by rapid urbanization in recent decades as humans continue building into nature, including areas that have historically experienced frequent natural wildfire activity, the data showed.

More frequent, intense and variable extreme weather events, known as compound events, are another factor currently fueling wildfires in parts of the West -- like California.

In recent years, parts of the state went from experiencing a major drought to an extended period of above average precipitation that allowed for abundant vegetation growth. A stretch of intense, record-breaking heat then followed, drying out much of this vegetation providing ample fuel for large and fast-growing wildfires.

Larger, more intense and more destructive wildfires are worsening air quality in many regions of the contiguous U.S. and Alaska, according to the federal government's Fifth National Climate Assessment.

But climate change was not the primary factor that led to the severity of the wildfires.

A perfect storm of weather and climate conditions, such as Santa Ana wind gusts up to 100 mph and low humidity, allowed for the rapid spread of the flames.