I received a few emails, mostly from surfers, asking about a study that was published this month in Nature Communications by the Institute of Marine Sciences at the University of California, Santa Cruz. The report stated that wave power had increased globally by 0.4 percent per year since 1948, and this increase is correlated with rising sea-surface temperatures.
About three years ago, I wrote a column about increasing wave energy based on data from the Diablo Canyon Power Plant’s waverider buoy deployed along the Pecho Coast (the shoreline between the Point San Luis Lighthouse and Point Buchon).
This wave measurement station has been in existence since June 1983 and is one of the longest continuous wave monitoring stations along the West Coast. You can view the historical wave data archive from this station at the Coastal Data Information Program (CDIP) at Scripps Institute of Oceanography. CDIP maintains an extensive network of buoys that monitor waves along the coastlines of the United States.
In the 35-plus years that the waverider buoy has been deployed off the Pecho Coast, the wave archive indicates about a 5 percent increase in longer-period wave events, linked directly to a pattern of more intense storms in Pacific with lower air pressures and stronger winds. I’m not sure what wave-energy spectrum parameters or locations the Santa Cruz team utilized, but it’s clear that wave energy is increasing, and sea-surface temperatures are rising. Here’s why:
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NASA and the National Oceanic and Atmospheric Administration (NOAA) announced that Earth’s global average temperature for 2017 was the third warmest year in NOAA’s 138-year climate record, behind 2016 (warmest) and 2015 (second warmest). With that terrible bit of news about the atmosphere, it’s sobering to think that the oceans are taking the brunt of global warming.
They have absorbed more than 90 percent of the excess heat.
Years ago, NASA launched two satellites from Vandenberg Air Force Base — Jason 1 in 2001 and Jason 2 in 2008. In 2016, NOAA and the European Organization for the Exploitation of Meteorological Satellites launched Jason 3 into space from Vandenberg 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.
Jason 3 has a goal to measure sea-level variations of 1 inch.
These satellites are indicating that sea-level rise continues to accelerate and is currently at approximately 3.2 millimeters per year. You see, when the water warms, it expands.
Consequently, this pushes sea levels higher over time. Therefore, this makes sea-level variation an essential indicator of climate change. In short, we are seeing rising sea levels from global warming.
Not only are these warmer seawater temperatures increasing sea level but also helping in generating stronger storms. As the atmosphere warms due in part to a warmer ocean, it’s able to hold more water vapor. When this water vapor condenses over the Pacific, it liberates vast 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.
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. I’ve been forecasting weather along the Central Coast since 1992, and I’ve seen a marked increase in North Pacific storms generating hurricane-force winds.
The stronger the winds that blow across the Pacific, the higher the seas they generate. Waves are created by the friction or the dragging motion of the wind over the water. These and a few other factors determine if ocean waves are small ripples or frighteningly large, cascading walls of water. As seas develop in the storm, they can reach only a 7-to-1 ratio of wavelength to wave height. Specifically, a wave with a 7-foot length can reach only 1 foot in height before it breaks.
When the wave breaks, longer wavelengths develop, allowing the seas to increase in height.
When the seas move out from under these gales, they become swells.
Only the most intense storms can generate swells with 20- to 30-plus second periods. These high-energy waves, combined with increasing sea level, storm surges, storm runoff and tides put billions of us who live along the world’s coastlines in harm’s way. Regrettably, we continue to dump about 2.57 million pounds of carbon dioxide into the air every second from the burning of fossil fuels. In California, the most significant contributor to greenhouse gas emission is transportation. An excellent way to reduce your carbon footprint is to drive an electric vehicle.
To learn more, please visit www.pge.com and click on the “solar & vehicles” tab.