What Do Recent Historic Heat Waves Mean for Us? A Q&A With SJSU Meteorologist and Climate Scientist Alison Bridger

The SJSU Wildfire Interdisciplinary Research Center truck overlooks the drought-stricken landscape of Coyote Valley on the outskirts of San José. More wildfires, severe droughts and extreme heat waves are all results of climate change. Photo: Robert C. Bain

Last month, temperatures in the Pacific Northwest reached historic and dangerous levels, like nothing the region has ever experienced before.

In fact, more than 100 Oregon residents died from heat-related illnesses during the record-shattering heat wave, which drove temperatures up to 117 degrees Fahrenheit in some parts of the state. Compare that to 12 hyperthermia deaths reported statewide between 2017 and 2019, according to CNN.

Parts of British Columbia hit 121 degrees Fahrenheit during the heat wave — the highest temperature ever recorded in Canada.

Alison Bridger, professor of meteorology and climate science

What should we make of this phenomenon? Alison Bridger, professor of meteorology and climate science at San José State, has some answers about why this extreme weather occurred in an area known for its cool climate — and how likely it is to happen again.

Q: We know the recent record-breaking heat in the Pacific Northwest was extremely dangerous. Can you give insight as to just how abnormal it is to see temperatures that high in that area?

AB: In the old days, when a high-temperature record got broken, it would be by 1 or 2 degrees. The Pacific Northwest heat dome was shattering records by as much as 10 degrees, which is why there was so much buzz.

It also remained very warm at night, providing little chance for anybody to cool down. Plus, it was in an area where few people use air conditioners — and stayed in place for days — so there was a lot of potential for heat stress, which is when the body can’t get rid of excess heat. As a result, there were many sudden deaths in the Pacific Northwest and in Western Canada.

One more thing is in the west, the highest temperatures tend to occur in July and August, not June.

Q: You used the term “heat dome.” Can you explain what that is and why it’s important?

AB: We meteorologists measure and pay attention to air pressure. In particular, we pay attention to areas where air pressure is higher or lower than average. Our weather is closely linked to whether we have a high- or low-pressure area over us.

Low pressure is associated with warm and cold fronts, clouds and rain — the kind where it rains all morning. High pressure areas are generally clear and dry with no clouds and no rain.

So a heat dome is an example of a high-pressure system — with clear skies, long days and the sun high in the sky. These are typical in the Southwest on really hot days in Death Valley, Las Vegas, Phoenix, etc. When they form, they can sometimes spread their influence further west and can even reach us at the coast, hence our Bay Area heat waves that occur one to three times a year.

We had another notable heat dome event this year, which was centered south and east of us and resulted in a temperature of 128 degrees Fahrenheit in Death Valley. This was a very strong heat dome and covered much of the west. We got over 100 degrees Fahrenheit in San Jose!

Q: How likely is it that we’ll see these temperatures again soon? Will this become a regular occurrence?

AB: I think so. Climate scientists have been warning about the impacts of climate change for decades, and here we are, seeing those predictions come true. More extreme heatwaves? Check. More rain in the Northeast? Check. More drought in the Southwest? Check. Melting ice caps? Check.

We might not see this type of occurrence every year, but it’s going to be more frequent and will likely occur again within the next five years. As we continue to add greenhouse gases to the atmosphere, we will continue to warm, and new extreme events will continue to emerge.

Q: What kind of impact do higher than normal temperatures have on our environment?

AB: Here are some major impacts:

  1. Changes to growing seasons — but if there’s less or no water for irrigation, that won’t matter.
  2. Less snow in the mountains, hence less water in reservoirs for western cities.
    More electrical demand for AC.
  3. Drier forests (trees and vegetation dry out more rapidly after rains due to warmer temperatures), leading to more wildfires.
  4. Animals that live in the mountains are being forced uphill to cooler areas. But when they reach the top, then what?
  5. I’ll bet there’s a human stress impact. People have been told for decades that climate change is coming, and now it’s obviously here, and we’re not doing anything. I know I’m stressed!

Q: Is there any hope that we can make improvements and possibly limit this in the future? If so, what needs to happen?

AB: If we were to suddenly stop adding more greenhouse gases and our carbon dioxide levels become stable, I think the atmosphere would continue to change for maybe 10 to 20 years due to its inertia. Then in 20 years, say, things would settle down to a “new normal,” which would be warmer, but we could start to deal with the consequences.

But, if we wait another 20 years and keep adding greenhouse gases, and then do the above, we’ll be at a warmer new normal, with more impacts that are more extreme and more widespread.

One way we could tackle this is to move faster on colonizing the moon and Mars, so we have an escape hatch. Or, we could work to fix this by moving much faster on cutting greenhouse gas emissions. This has to be a global effort, but we in the U.S. can get started regardless.

Let’s generate more solar, wind and tidal energy; do a better job on battery storage; do a better job on power transmission; and use smart devices to use less energy. And let’s provide serious incentives for getting these big tasks done.

Learn more about the SJSU Department of Meteorology and Climate Science.