The blob is back. Since 2014, a mass of unusually warm water has hovered and swelled in the Pacific Ocean off the West Coast of North America, playing havoc with marine wildlife, water quality and the regional weather. Earlier this year, weather and oceanography experts thought it was waning. But no: The Blob came back, and it is again in position off the coast, threatening to smother normal coastal weather and ecosystem behavior. The Blob isn’t exactly to blame for California’s drought, though it certainly aggravated the problem.