National Geographic : 2016 Sep
HEAT WAVE 61 Kachemak Bay in Homer, Alaska, inching to- ward a wheezing, dying sea otter sprawled out on the shore. Otter deaths are skyrocketing on the shoreline beneath the snowcapped Kenai Mountains, so Lefebvre is here to see whether the fates of these otters and whales are some- how intertwined. In the past few years death had become a big- ger part of life in the ocean off North America’s West Coast. Millions of sea stars melted away in tide pools from Santa Barbara, California, to Sitka, Alaska, their bodies dissolving, their arms breaking free and wandering off. Hun- dreds of thousands of ocean-feeding seabirds tumbled dead onto beaches. Twenty times more sea lions than average starved in California. I watched scientists lift sea otter carcasses onto orange sleds as they perished in Homer—79 turned up dead there in one month. By year’s end, whale deaths in the western Gulf of Alaska would hit a staggering 45. Mass fatalities can be as elemental in nature as wildfire in a lodgepole pine forest, whipping through quickly, killing off the weak and clearing the way for rebirth. But these mysterious casualties all shared one thing: They overlapped with a period when West Coast ocean waters were blowing past modern temperature records. As hotter oceans destroy coral reefs in the tropics and melting ice alters life in the Arc- tic, it’s been easy to overlook how much warm water can reshape temperate seas. No more. Between 2013 and earlier this year, some West Coast waters grew so astonishingly hot that the marine world experienced unprecedented upheaval. Animals showed up in places they’d never been. A toxic bloom of algae, the biggest of its kind on record, shut down California’s crab industry for months. Key portions of the food web crashed. It’s not clear if greenhouse gas emissions exacerbated this ocean heat wave or if the event simply represented an outer edge of natural weather and climate patterns. But the phenomenon left daunting questions: Was this a quirk, an unlikely confluence of extremes that conspired to make life harsh for some sea crea- tures? Or was it, as one scientist says, a “dress rehearsal”—a preview, perhaps, of what hotter seas may one day bring as climate change un- leashes its fever in the Pacific? While Lefebvre and I are pondering our next move, a radio call comes in. Another dead otter has surfaced on Homer Spit, five miles away. We retrace our steps to a dusty parking lot, pile into a pickup, and head off. BEGINNING IN LATE 2013, a bewildering patch of warm water formed in the Gulf of Alaska. A stubborn atmospheric high-pressure sys- tem, nicknamed the “Ridiculously Resilient Ridge,” was keeping storms at bay. Just as blow- ing across hot coffee frees heat, winds usually churn and cool the sea’s surface. Instead, heat within this shifting mass, which University of Humpback whales feast on fish in Monterey Bay, California. Anchovies were scarce in many areas in 2015, but so many congregated in the bay that Jim Harvey, director of Moss Landing Marine Labs, watched from his window as 50 or 60 whales dined on them at once. “That’s not normal,” he says.