This July, a massive record-setting heat dome locked over the central and western United States, putting roughly 70 to 80 million people under extreme heat warnings and advisories.
Researchers at La Jolla’s Scripps Institution of Oceanography, which has been tracking coastal ocean temperatures daily for 110 years since 1916, report that a prolonged marine heatwave has kept Southern California coastal waters significantly above average.
Data from the Scripps Pier tracking program shows persistent high-pressure systems reducing cold water upwelling, leading to local water temperatures 3 to 7 degrees Fahrenheit above normal and stressing marine ecosystems. This century-long dataset shows that the coastal Pacific has warmed by roughly 3°F (about 1.6°C) over the past 110 years.
What does this all mean? Are these weather phenomena linked?
To find out, Times of San Diego held a Q&A with Art Miller, a Distinguished Research Oceanographer Emeritus and a senior lecturer in climate sciences at Scripps Institution of Oceanography (UCSD).
Miller is a physical oceanographer who studies oceanic influences on climate variability using a combination of computer simulation models and observational analysis. He has authored or co-authored more than 100 refereed publications. His research extends from basic issues in dynamical oceanography to a variety of topics in climate dynamics, including regional impacts of global climate change and oceanic ecosystem response.
Times of San Diego: Is there a link between the recent heat dome effect and gradually rising ocean temperatures?
Miller: I searched the published literature and did not find any evidence linking heat domes to El Niño events, which is what I expected. Heat domes occur naturally in the climate system.
What is obvious is that the intensity of the heat domes is increasing due to the accumulation of more heat in the climate system due to the increasing greenhouse gases from fossil fuel burning. On occasion, such as during an El Niño event (a natural climate pattern involving warming of ocean surface waters), the ocean can release some of that stored excess heat, which was trapped below the surface of the ocean, into the atmosphere.
During La Niña, the opposite happens, and the tropical Pacific draws down some of that excess heat, storing it subsurface until the next El Niño.
Times of San Diego: We’ve been hearing a lot about the ocean warming up, with Scripps recording the warmest temperatures we’ve ever seen. Is this impacting climate change on land?
Miller: The ocean off our coast serves as a cooling mechanism because the water has high heat capacity (ability to store heat) compared to air. When the oceanic waters are anomalously warm, depending on the magnitude of the anomaly and the spatial scale of the Marine Heat Wave (MHW), it can affect our weather in different ways, depending on the season.
In the winter, during the rainy season, storms that pass over the marine heat wave can pick up some extra moisture and cause coastal rainfall to be increased [In our recent modeling study we found roughly a few-percent increase in northern California precipitation, and up to 50% increase in Southern California for one winter’s set of storms].
Times of San Diego: Is the kelp die-off in the ocean off La Jolla a consequence of our continually warming ocean?
Miller: Kelp is a complicated and resilient species that thrives in cool, nutrient-rich water, as we have here off California. It grows rapidly, but can get knocked out by heavy surf, and is sensitive to rising temperatures of the ocean. Invasive species can disturb kelp’s ability to cling to the ocean bottom.
Times of San Diego: Is the recent temperature increase in Phoenix, approaching the highest temperature ever recorded there a couple of years ago, a consequence of climate change? Are we likely to see this increase escalate even further over time?
Miller: In the same way that marine heat waves ride on the background trend, heat waves in the air do the same. With more heat available to “pile up” into heat domes or in regions that have summer-season descending air (the desert latitudes like Phoenix is in), the excess heat is expected to cause increased chances of setting record high temperatures. (In another recent theoretical modeling study) we found that maximum surface temperatures on Earth do not simply rise with the background trend of global warming. Instead, they rise about 30%-40% faster than the global warming trend.
Times of San Diego: Have we reached/crossed the tipping point with greenhouse gas emissions and climate change, where things will only get progressively worse from here?
Miller: The specific meaning of tipping point in climate science is that once you get there — you cannot go back to the way it was. Under that mathematical definition, I would say no. … (But) I cannot state that we have not passed a tipping point.
What is obvious, though, is that, even if we stopped burning fossil fuels, the climate system would still take many years (decades?) to come to equilibrium. That is, the system will continue to heat up and thereby alter the basic seasonal weather conditions that many of us grew up with and no longer experience. If we did shut off the greenhouse gas pollution right now and additionally seek ways to capture carbon from the system and sequester it, we may be able to return our climate system to some degree of “normalcy.”
Times of San Diego: What do you say to people who continue to deny that climate change is occurring, insisting it’s just natural climate variation?
Miller: I ask them, “Who do you think is making the real money from burning fossil fuels?” If they are interested, I’ll explain why the industry has purposely put out misinformation and lies for many decades, much like the same guys did for the tobacco industry and lung cancer. I know that many people are trapped in their tribal culture, whether societal, religious, or whatever, and to challenge the myths they embrace is often unfeasible. But if they really want to learn, I’ll do the best I can to explain things. And if they still don’t want to face reality, who am I to do more than say, “Well, let’s have a drink together and talk sports!”
