Birch leader weighs in on weird weather

Scientists suggest it’s a mild La Nina

By Tina Safi


Winter or summer, the San Diego region often boasts the same forecast: 75 degrees, sunny and mild.

This year, however, locals and tourists are talking about a difference. June’s murkiness has entered July, and the coastal weather has gone back and forth between unbearably hot and unusually chilly.

“We’ve certainly gone from a May gray to a June gloom, and now I suppose we are in a sad July,” said Nigella Hillgarth, executive director at Birch Aquarium at Scripps Institution of Oceanography since 2002. “The scientists of oceanography at Scripps are suggesting a mild La Nina, which occurs when colder water comes north with strengthening trade winds. This is opposed to El Nino, which happens when the trade winds slacken.”

Since La Nina and El Nino are opposites, the effects of each phenomenon vary drastically. Whatever the effects, however, when weather changes more consistently over longer periods, according to Hillgarth, it might be attributed to a larger climate change. The frequent La Ninas and El Ninos of the last few years may signify a global shift in climate, she noted in an interview last week.

Hillgarth, who received her master’s degree in zoology and doctoral degree in animal behavior from Oxford University, does point out a distinction, however.

“When change occurs over decades, it is called a climate shift,” she said. “When it happens over a few years, it is simply a weather shift, which may be what we are experiencing right now.”

Weather and climate shifts aside, what about that fog that seems to permanently haunt all of San Diego’s coastal towns?

“When cold water reacts with warm air, which is a whole other phenomenon, it gives you this foggy marine layer,” Hillgarth said.

As far as giving San Diegans an extended weather forecast, Hillgarth is reluctant to comment. Weather predictions can be, as any weatherman can attest, pure guesswork sometimes.

“In the coming years, we do need to look at July weather as perhaps not being as bright as it used to be,” Hillgarth said. “Hopefully, this weather won’t go on much longer. If we look at what happened the year before last, when we were having another mild La Niña, we could guess that this weather will end around August.”

The bigger picture, according to Hillgarth, suggests global warming, a link that might explain why we are seeing more frequent La Ninas and El Ninos. Scientists at Scripps have, in fact, indicated that because the frequency of these strange weather phenomena have been increasing, global warming might be at play.

Surfers, however, needn’t worry, at least not yet, because “our particular conditions would not affect sea level,” Hillgarth said.

While the fact that oceans as a whole are warming would affect the sea level, so many factors affect the sea level that it is very complex. The warming of the planet as a whole is connected to sea level rise and ocean conditions, which are beginning to change due to global warming, she noted.

This unusual weather shouldn’t make San Diegans any less vigilant about wildfires, as Hillgarth insists that the “danger from wildfires is as present as ever in Southern California.”

Will fall weather have to be the region’s saving grace?

“Well, my own optimism says that our fall weather will be wonderful,” Hillgarth said.