Quantcast

How Climate Change Ignites Wildfires From California to South Africa

Climate
A wildfire near Santa Barbara, California. John Newman / U.S. Forest Service

The link between climate change and more frequent, severe wildfires is well-known, but two new studies published in Geophysical Research Letters this month provided more insight into exactly how warming temperatures are increasing fire risk around the world.

In fire-weary California, urbanization and global warming are increasing ground temperature along the southern coast, decreasing cloud cover and increasing the risk of wildfires.


Meanwhile, in the Mediterranean and temperate parts of the Southern Hemisphere, it's what comes out of the clouds that causes the problems: Lightning-ignited fires are on the rise and likely to keep rising with global temperatures.

The California study was published May 24 and reported by Columbia University in Phys.org Wednesday.

"Cloud cover is plummeting in southern coastal California," study co-author and Columbia University bioclimatologist Park Williams said. "And as clouds decrease, that increases the chance of bigger and more intense fires."

The researchers found low-lying summer clouds in the Los Angeles area had decreased by 25 to 50 percent since the 1970s. The decrease in cloud cover was mostly driven by urbanization, which increases the temperature of the ground, but overall global warming also contributed. Warmer ground drives away clouds, which leads the direct sunlight to heat the ground further, drying out vegetation and increasing the chance that it catches fire.

The study found that the total area burned by fires in Southern California had not increased, mostly because urbanization had also decreased the amount of burnable land and because firefighting techniques had improved.

"Even though the danger has increased, people in these areas are very good at putting out fires, so the area burned hasn't gone up," Williams said. "But the dice are now loaded, and in areas where clouds have decreased, the fires should be getting more intense and harder to contain. At some point, we'll see if people can continue to keep up."

Williams said that reduced cloud cover was likely not behind 2017's devastating fires, which were caused by wind, a dry fall and a surfeit of burnable vegetation that had grown in the record rains following California's record drought.

The lightning study was published May 15 and reported by Portland State University Thursday in Phys.org.

The study looked at the relationship between the frequency of lightning-started fires, warming temperatures overall and the impact of three regular climate-altering phenomenons: El Niño-La Niña, the Indian Ocean Dipole and the Southern Annular Mode.

The study found that warming temperatures increased the frequency of fires, and also increased the influence of all three climate phenomena on fires in the warmer early 21st century compared to the end of the 20th.

"We think that by having warmer oceans and warmer temperatures in general, we're going to see higher evaporation and heat transfer, and thus higher frequency of convective storms that in turn results in more lightning-ignited fires," study co-lead author and Portland State University geography professor Andrés Holz said.

Fires especially increased due to the activity of the Southern Annular Mode (SAM), the north-south movement of westerly winds that circle Antarctica and bring moisture to the southwest tip of continents in the Southern Hemisphere. This is because during the "positive phase" of SAM, when the westerly winds retreat to Antarctica, global warming and the hole in the ozone layer have combined with the climate driver to increase heat and decrease precipitation in Australia, South Africa and southern South America.

Worldwide, Holz said that, unless global rainfall patterns changed, global warming was likely to increase fires in wet regions that had previously been too humid for fires, but would decrease fires in historically dry regions.

EcoWatch Daily Newsletter

Natural Resources Defense Council

By Emily Deanne

Shower shoes? Check. Extra-long sheets? Yep. Energy efficiency checklist? No worries — we've got you covered there. If you're one of the nation's 12.1 million full-time undergraduate college students, you no doubt have a lot to keep in mind as you head off to school. If you're reading this, climate change is probably one of them, and with one-third of students choosing to live on campus, dorm life can have a big impact on the health of our planet. In fact, the annual energy use of one typical dormitory room can generate as much greenhouse gas pollution as the tailpipe emissions of a car driven more than 156,000 miles.

Read More Show Less
Kokia drynarioides, commonly known as Hawaiian tree cotton, is a critically endangered species of flowering plant that is endemic to the Big Island of Hawaii. David Eickhoff / Wikipedia

By Lorraine Chow

Kokia drynarioides is a small but significant flowering tree endemic to Hawaii's dry forests. Native Hawaiians used its large, scarlet flowers to make lei. Its sap was used as dye for ropes and nets. Its bark was used medicinally to treat thrush.

Read More Show Less
Sponsored
Frederick Bass / Getty Images

States that invest heavily in renewable energy will generate billions of dollars in health benefits in the next decade instead of spending billions to take care of people getting sick from air pollution caused by burning fossil fuels, according to a new study from MIT and reported on by The Verge.

Read More Show Less
Aerial view of lava flows from the eruption of volcano Kilauea on Hawaii, May 2018. Frizi / iStock / Getty Images

Hawaii's Kilauea volcano could be gearing up for an eruption after a pond of water was discovered inside its summit crater for the first time in recorded history, according to the AP.

Read More Show Less
A couple works in their organic garden. kupicoo / E+ / Getty Images

By Kristin Ohlson

From where I stand inside the South Dakota cornfield I was visiting with entomologist and former USDA scientist Jonathan Lundgren, all the human-inflicted traumas to Earth seem far away. It isn't just that the corn is as high as an elephant's eye — are people singing that song again? — but that the field burgeons and buzzes and chirps with all sorts of other life, too.

Read More Show Less
Sponsored
A competitor in action during the Drambuie World Ice Golf Championships in Uummannaq, Greenland on April 9, 2001. Michael Steele / Allsport / Getty Images

Greenland is open for business, but it's not for sale, Greenland's foreign minister Ane Lone Bagger told Reuters after hearing that President Donald Trump asked his advisers about the feasibility of buying the world's largest island.

Read More Show Less
AFP / Getty Images / S. Platt

Humanity faced its hottest month in at least 140 years in July, the US National Oceanic and Atmospheric Administration (NOAA) said on Thursday. The finding confirms similar analysis provided by its EU counterparts.

Read More Show Less
Newly established oil palm plantation in Central Kalimantan, Indonesia. Rhett A. Butler / Mongabay

By Hans Nicholas Jong

Indonesia's president has made permanent a temporary moratorium on forest-clearing permits for plantations and logging.

It's a policy the government says has proven effective in curtailing deforestation, but whose apparent gains have been criticized by environmental activists as mere "propaganda."

Read More Show Less