Once a year in June, sea lion mothers on the Channel Islands give birth to a pup. For the next 11 months, the mothers swim off to forage for days to provide food for themselves and milk for their progeny. But in early 2015, calorie-dense sardines and anchovies – the best food – were hard to find. The mothers were forced to dive deeper and swim farther, and by the time they returned to the islands, they didn’t have much milk to offer. The health of those fish populations is driven by climate, said Dave Checkley, an oceanography professor at Scripps Institution of Oceanography at UC San Diego. Specifically, it’s the way climate affects wind and ocean currents.