Northern California is ablaze with wildfires.
As of Thursday, according to CalFire, 22 wildfires are burning in the Golden State. They have scorched over 190,000 acres and forced the evacuation of entire neighborhoods. Officials say at least 26 people have been killed and more than 400 are missing. In terms of property damage, they conservatively estimate that 3,500 homes and structures have been destroyed.
The smoke and ash from these fires are also causing widespread air quality issues. In the Bay Area, well outside of the burn zone, air quality reached historically poor levels this week.
These huge fires are largely the result of climate whiplash. California has distinct wet and dry seasons, but they have been extreme recently. After years of drought, this winter brought the state record amounts of precipitation that spurred explosive new plant growth. Then during the summer, which was the state’s warmest on record and unusually dry, all that vegetation turned to tinder.
Making matters worse, the region’s seasonal winds known as the Diablo Winds began blowing over the weekend. They reportedly reached speeds as high as 70mph in some areas. Blowing east to west, these winds warm from compression as they flow downslope from the mountains towards the coast and dry out vegetation even further. They also fan the flames of any fire already burning and can cause it to spread very quickly.
The Diablo Winds are essentially the same type of air current as the famous Santa Ana winds in southern California. They only really differ in location and name. The Diablo Winds are named for Mount Diablo in the East Bay area and the Santa Ana Winds are the namesake of Santa Ana Canyon in Orange County.
Wildfires are not unusual in California, but this outbreak is considered one of the worst in state history. The exact cause of the fires is still unknown.
Wildfire burns near Glen Ellen, CA. Credit: The SF Chronicle
Hurricane Nate, the 14th named storm of the 2017 Atlantic Hurricane season, made two landfalls along the US Gulf Coast this weekend. The first was near the mouth of the Mississippi River in Louisiana and the second was near Biloxi, Mississippi.
Coming ashore with 85mph winds, this category-1 hurricane generated a significant storm surge that swamped parts of the region from Louisiana to the Florida Panhandle. One of the hardest hit areas was Pascagoula, MS where a storm surge of 6.3 feet was reported. The storm also downed trees and caused widespread power outages.
Moving inland, Nate was soon downgraded to a tropical depression. However, it still spawned a number of destructive tornados from Alabama to North Carolina. They ranged in strength from EF-0 to EF-2.
Nate was the first hurricane to make landfall in Mississippi since Katrina in 2005.
Credit: NOAA/NASA GOES
There are a number of key indicators, beyond our rising global temperature, that show Earth’s climate is changing. One of these is Arctic sea ice.
Measured via satellite since the late 1970’s, the extent and thickness of sea ice tend to vary from year to year but both have been in an overall decline for decades. According to NASA, the melt season in the Arctic has increased by 37 days since 1979.
Sea ice extent, the area of ocean with at least 15% sea ice, has a strong seasonal cycle. It typically peaks in March as winter ends and then declines during the summer, reaching a minimum in September. In March 2017, it hit a record low maximum for the third year in a row. The record minimum occurred in September 2012.
According to the National Snow and Ice Data Center, the average age of Arctic sea ice is also changing. Thick multi-year ice – the ice that lasts through at least one melt season – has decreased 11% per decade since the satellite era began. That means there is more first-year ice, which tends to be thin and brittle. This is troublesome because it is more vulnerable to warming temperatures and wave action.
Sea ice is frozen ocean water. It forms, grows, and melts in the ocean. In contrast to land ice (glaciers), it does not contribute to sea level rise. However, as it melts it creates a global warming feedback loop. Ice is lighter in color and reflects more sunlight than dark ocean water. So, as more ocean water is exposed, more of the sun’s energy is absorbed. This drives temperatures up even further and causes more ice to melt.
The Arctic is now warming twice as fast as the rest of the planet – a phenomenon known as “Arctic amplification.” At this rate, scientists expect the region to be ice-free in summer by the 2030s.
September 2017 felt like a temperature roller coaster in New York City. Highs ranged from an unseasonably cool 66°F to a record warm 91°F. But with eighteen of the month’s thirty days posting above average readings, the heat won out in the end. The city’s mean temperature for September was 70.5°F, which 2.5°F above average.
In terms of precipitation, the month was mostly dry. Only 2.0 inches of rain was measured in Central Park, marking the third month in a row to deliver below average rainfall. The city usually gets 4.28 inches of rain in September.
Credit: The Weather Gamut