Weather Watch

Global warming threatens coastal communities

High tide in Baywood Park.
High tide in Baywood Park.

NASA, the National Oceanic and Atmospheric Administration and the World Meteorological Organization all announced that 2015 was the hottest year on record, shattering the previous record set in 2014 by more than one-tenth of a degree Celsius.

Unfortunately, 2015’s average temperature has already taken the earth’s atmosphere halfway toward the 2-degree global warming mark that most climatologists agree would produce catastrophic climate change. With that terrible bit of news about the atmosphere, it’s sobering to think that the oceans are taking the brunt of global warming. In fact, they have absorbed more than 90 percent of the excess heat along with melting glaciers and ice sheets in both hemispheres.

When water warms, it expands. Consequently, this pushes sea levels higher over time. This makes sea-level variation a vital indicator of climate change. In short, we are seeing rising sea levels from global warming. This, combined with waves generated by high winds, storm surges, storm runoff and tides, put billions of us who live along the world’s coastlines in harm’s way. That is currently being put into sharp focus with areas along the California coast that are susceptible to severe coastal erosion, such as the community of Pacifica just south of San Francisco where apartment buildings and homes have been abandoned as they threaten to slide into the ocean.

Satellites have been measuring this threat. Years ago, NASA launched two satellites from Vandenberg Air Force Base — Jason 1 in 2001 and Jason 2 in 2008. This January, NOAA and the European Organization for the Exploitation of Meteorological Satellites launched Jason 3 into space from Vandenberg Air Force Base with help from NASA and Space X.

“These satellites give us a global view of our changing oceans with such exquisite accuracy that even the yearly rise and fall of global sea level is visible, caused by the transfer of water to and from the continents in the form of rain and river runoff,” said climate scientist Josh Willis of NASA’s Jet Propulsion Laboratory in Pasadena.

They measure sea levels using an extremely precise radar altimeter. The altimeter transmits radio waves from the satellite to the ocean’s surface and measures the time it takes for the radio waves to bounce back. This technique has proved to be particularly precise and accurate. In fact, Jason 3 has a goal to measure sea-level variations of 1 inch.

Locally, an interesting way to measure climate change is to study wave data from Diablo Canyon nuclear power plant’s Waverider buoy. As the atmosphere warms, it’s able to hold more water vapor. When this water vapor condenses over the Pacific, it liberates great amounts of latent heat and causes a rapid and sharp drop in air pressure that can create storms with hurricane force winds.

Over the decades, these North Pacific storms have become more intense. In fact, a storm from the remnants of Typhoon Nuri in November 2014 intensified to 924 millibars in the Bering Sea. This was the lowest pressure ever recorded in the North Pacific region. The previous record was 925 millibars recorded at Dutch Harbor in October 1977. More often than not, the lower the pressure, the stronger the winds that blow across the Pacific, and then they generate higher seas and eventually a longer-period swell.

In the 35-plus years that the Waverider buoys have been deployed off the Pecho Coast, the wave data archive indicates about a 5 percent increase in longer-period wave events, linked directly to lower air pressures in North Pacific region storms. Higher sea levels and longer-period waves will lead to greater amounts of coastal flooding and erosion.

Regrettably, we continue to dump about 5 million tons of carbon dioxide into the atmosphere every hour from the burning of fossil fuels.

“The increase in the rate at which the average global sea level is rising is just what is expected from climate models,” astronomer Ray Weymann said. “Many low-lying areas, like Miami, are already feeling the impacts. It will only get worse unless we quickly control CO2 emissions.”

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In the United States, the generation of electricity is one of the largest contributors of CO2. However, more than 55 percent of electricity PG&E sends to its customers is carbon-free electricity, generated by nuclear power at Diablo Canyon Power Plant, hydroelectricity, solar, wind, geothermal and biomass.

John Lindsey’s column is special to The Tribune. He is PG&E’s Diablo Canyon marine meteorologist and a media relations representative. Email him at pgeweather@pge.com or follow him on Twitter @PGE_John.

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