Not every change to LA’s air has been bad.
“In a place like Santa Monica, where we've cut the … number of cloudy hours per day almost in half,” he explains, “this has caused about a 22 degree Fahrenheit warming.” The air is cleaner. And even just two hours per day of direct sunlight has made a noticeable difference in our temperature. Williams’ research has found that the average day in Santa Monica 50 years ago saw about four hours of marine fog. And that means the clouds are getting thinner and they're burning off earlier in the day,” says UCLA Geography Professor Park Williams. But the tops of the clouds aren't rising. “Summertime clouds in Los Angeles have been rising - that is, the base of the cloud is getting further away from the ground. June gloom might be the bane of beachgoers, but it also serves as California’s natural air conditioner.īut since the 1970s, about half of the marine layer has disappeared. That’s especially bad news for night time temperatures, which have continued to increase as well, eliminating some of the overnight relief Angelenos rely on during heat waves. And as the air gets warmer, it’s able to hold more moisture. As the ocean gets warmer, it evaporates more. Rising temperatures contribute to rising humidity. That converts to about a 1 degree Fahrenheit rise in temperature that actually feels more like a 4 degree rise – just since the mid-90s. But if you include that humidity effect, it is more like … 2 degrees,” says UCSD Meteorologist Guang Zhang. “Over the past 25 years in LA, the temperature increase was … about half a degree. That difference is heightened in Los Angeles, which was a traditionally drier climate. The air is wetter too, which means the heat index has increased even more. That makes cities better at soaking in heat from the sun. Compared with rural areas, cities have more black asphalt, more buildings, more car exhaust, and less tree canopy. The parking lot is packed at Santa Monica beach, July 25, 2022. The problem is greatest in parts of Southern California that have seen more development, such as Santa Clarita, which over the past 50 years has transformed from a rural community into the third-largest city in LA County. “If we just keep replacing more and more open space with impervious stuff, we're going to keep increasing the geographic extent of anything that could contribute to the heat island,” says UCLA Urban Planning and Geography Professor Kelly Tuskin. Los Angeles is especially prone to this problem because of its notorious urban sprawl.
That’s thanks to the urban heat island effect. We’re heating up more than almost anywhere else in the country. But LA is warming faster than most places, averaging more than 4 degrees Fahrenheit higher than it was in the 19th century. Heightened greenhouse gas emissions have warmed the planet by about 1.4 degrees Fahrenheit. Of course, it’s hotter almost everywhere. But how much? It’s hotter than it used to be. And Southern California’s marine layer is shrinking. Many Angelenos have noticed a major difference in the county’s air over the past few years.
0 kommentar(er)
