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. But it is to blame for seriously disrupting the ocean food chain and for creating conditions that fed unprecedented algal blooms in the coastal Pacific.
With the Blob back in play again, what does it mean for the winter ahead? To find out, Water Deeply spoke with Nicholas Bond, a research meteorologist at the University of Washington in Seattle and Washington’s state climatologist. In June 2014, Bond named this persistent weather phenomenon, and later wrote the first scientific paper characterizing it.
Water Deeply: What exactly is the Blob?
Nicholas Bond: It’s a large mass of water in the northeast Pacific Ocean that’s considerably warmer than usual. It doesn’t have any real sharply defined boundaries, but it’s an area that, at times, has stretched from Baja California up to the Bering Sea. At other times, it’s kinda shrunk back down. It’s been at least 1,000 miles (1,600km) across and, recently, quite deep.
Typically, it’s been something like2.7–3.6F (1.5–2C) warmer than normal. But there have been places where it’s been as much as 9F (5C) warmer. It’s waxed and waned, but it’s been that way since early 2014. The warmer-than-normal water extends down to something like 300m (1,000ft) below the surface. So that’s a huge volume of considerably warmer-than-normal water.
Water Deeply: Is it still out there?
Bond: Yeah. There was sort of a reinvigoration this past summer. The temperatures were moderating early in 2016, and then, at least in a large area south of Alaska and off the coast of the Pacific Northwest, it really warmed up again this past summer.
Water Deeply: What causes it?
Bond: A lot of it, almost all of it, is due to just the unusual weather patterns that have been occurring over the northeast Pacific during the past few years. They haven’t been the same patterns, but what really got it started was when a ridge of higher-than-normal sea-level pressure set up during the winter of 2013–14 over the northeast Pacific.
That was a very persistent and strong ridge of higher-than-normal pressure that kind of blocked the usual parade of storms across the Pacific. That meant less heat was drawn out of the ocean into the atmosphere than usual. It meant there was less cold water (from the deeper ocean) mixing near the surface part of the ocean. And also the unusual winds meant the upper-level currents in the ocean were a little bit different from usual.
Water Deeply: Is it unprecedented?
Bond: Yeah, certainly. In terms of the magnitude of anomalies in a lot of locations, we haven’t seen anything quite like this. I did a fairly careful study using the data that’s available, going back decades. There have been other periods with considerably warmer-than-normal ocean temperatures in the region. But they were never of the kind of geographic extent and magnitude we’ve seen with this recent event.
Water Deeply: What caused that persistent high pressure?
Bond: It became known as the “ridiculously resilient ridge.” There’s been a number of independent studies that have basically shown that much warmer than normal waters in the far western tropical Pacific, in the vicinity of New Guinea – and thunderstorms that those warm waters helped spawn – had this kind of ripple effect on the atmospheric-circulation weather patterns over much of the globe.
It set up this series of very large-scale high- and low-pressure centers, with the ridge over the coast of western North America, and then a trough of lower pressure over the northeastern part of North America.
Water Deeply: How did the Blob affect the drought in California?
Bond: That same ridge of high pressure basically blocked the storms. There was just a real lack of those regular storms. The warm water didn’t cause the unusual weather patterns. But those unusual weather patterns that brought the warm water also were a large cause of the drought in California.
It turned out that was the same case in the Pacific Northwest. Not quite the same extent, but we were looking at very low snowpack in mid-February 2014. Then there was enough of a shift that we actually had a pretty wet period there at the end of winter and got enough rain and snow to kind of tide us through the summer of 2014. But there weren’t enough (storms), and those didn’t extend far enough south for California to get relief.
But it gets kind of complicated. Once that warm water formed out there in a big way, it does tend to warm the air that’s passing over it. Once that water was warmed, it did help warm the air coming off the ocean. This was especially the case in the winter of 2014–15. It led to warmer air temperatures and higher snow levels. The freezing level was 1,000–2,000ft (300–600m) higher than usual in the mountains. So that certainly ended up being a real problem. We count on that snowpack coming out of winter to get us through the summer. But it fell as rain rather than snow during that 2014–15 winter.
Water Deeply: Is there a climate change connection here?
Bond: This is sometimes called a marine heat wave, and it’s a short-term kind of event. There is some evidence that long-term trends are favoring the patterns we’ve had over the past few years. But that’s a very small effect.
So it’s not due to global warming. But it does provide some hint, at least, of what it’s going to be like in future decades, in particular, with some of the impacts we’ve seen in the marine ecosystem. What we’ve had the past few years is something that is liable to be more the rule rather than the exception toward the middle of the century. So maybe this is kind of a little preview or something. So we’re trying to learn from it.
Water Deeply: How has the Blob affected ocean life?
Bond: The impacts were quite a few and widespread. At the bottom of the food chain, we saw a higher preponderance at the plankton level of subtropical species versus ones that are more adapted to cooler water.
That had repercussions all the way up the food chain – everything from the kind of suitable prey for salmon that was present and whether they were getting the food they need, to some real problems with fur seals and sea lions in California in particular. In the Gulf of Alaska we had what National Oceanic and Atmospheric Administration has called a marine mammalmortality event last year. Seabirds are another one: There were some species with some very large mortalities, with lots more dead seabirdswashing up on the beaches.
One of the more alarming things is the harmful algal blooms. That was sort of way out there in terms of how far along the coast it stretched, how long it lasted, how high the toxin levels got. That was something that was really scary.
Water Deeply: How long will the Blob be with us?
Bond: That’s kind of the $64,000 question. We thought this whole event was winding down earlier this year, and then we’ve seen it rear its ugly head again in some locations.
Water Deeply: How will this affect our weather this coming winter?
Bond: The more prominent temperature anomalies are a little north of California. It’s all going to depend on the weather patterns. There are kind of borderline La Niña conditions now, which doesn’t tend to imply too much one way or another for Northern California. In the past, it probably has meant somewhat less precipitation than normal for Southern California. But we see a lot of exceptions there.
It’s kind of an admission of defeat, but it’s basically a crapshoot in terms of how much rain you get.
I think in terms of temperature, it’s not liable to be quite as warm as the past two winters, so that’s good, at least for the winter-sports folks. What falls in the mountains should be snow at the higher elevations. I think Northern California is liable to do OK. Southern California? Wow, that’s a tough one.
Oct 31 2016, Matt Weiser, Water Deeply
Image: NOAA