Mystery blob in the Pacific messes up US weather and ecosystemsAn unusual threat is looming off the Pacific coast of North America from Juneau in Alaska to Baja California. Now roughly 2000 kilometres wide and 100 metres deep, a mass of warm water that scientists are calling “the blob” has lingered off the coast for a year and a half and has set temperature records, with waters between 1 °C and 4 °C warmer than normal. Fresh research published in Geophysical Research Letters has examined the causes and impacts of this area of water, which has grown more recently. The blob has changed water-circulation patterns, affected inland weather and reshuffled ecosystems at sea. Although scientists say the planet’s warming oceans may not be responsible for the mysterious and long-lived anomaly, some see it as an early warning of changes that might be coming to the Pacific in the next few decades. Satellite imagery first alerted scientists to the strange formation in August 2013, when the roundish blob was seen over the Gulf of Alaska. Researchers think that a long-lasting weather pattern called a high-pressure “ridge” deflected winds that stir up cool waters from the deep and bring cool air and water from high latitudes.Months later, fishermen and officials around Alaska reported sightings of species found in more temperate or even tropical waters, including skipjack tuna, thresher sharks and sunfish. Other marine species showed up thousands of kilometres north of their normal ranges, including pygmy killer whales and tropical species of copepods – tiny crustaceans that are key to marine food webs. MORE