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San Diego’s ocean waters are warmer than usual. Last week, researchers recorded the warmest sea surface temperature in more than a century. Each day, researchers from the Scripps Institution of Oceanography at University of California San Diego collect data by hand from the Ellen Browning Scripps Memorial Pier. On Friday, the water reached 78.8 degrees Fahrenheit — the highest since record keeping began there in 1916. The previous record, 78.6 degrees, had been set just two days earlier. We spoke with Clarissa Anderson, a biological oceanographer, to explain the significance of the temperatures.

Her answers have been slightly edited and condensed for clarity:

How often is the water temperature measured and why?

We’ve done manual measurements on the waters near the pier since 1916, but we also have an automatic shore station and gliders that go further off the coast and buoys. All of those measurements tell us a comprehensive story about what’s going on in the ocean as a whole. And we’re seeing these high temperatures across the board.

While global warming was not an understood concept a century ago, even then there was an understanding that there’s natural variability and that temperatures could change very abruptly. The understanding was you’ve got to get a baseline understanding. There was a basic understanding that human causes could impact the sea and this was scientific curiosity taking that further.