A significant marine heat wave, referred to as a "blob," has re-emerged in the northern Pacific Ocean, leading to record-high ocean temperatures. Climate scientists warn this could result in a wetter-than-normal winter for the Pacific Northwest. According to Berkeley Earth, an independent organization that analyzes environmental data, northern Pacific temperatures were approximately 2.5 degrees Celsius warmer this August compared to pre-industrial averages. This marks a notable and potentially long-lasting change in ocean conditions.

The current temperatures in the northern Pacific are at unprecedented levels, exhibiting anomalies more commonly seen in land areas rather than vast oceanic regions. Scientists from Berkeley Earth indicate that this warming trend has been ongoing for the past three decades but has recently accelerated. Chris Harley, a zoology professor at the University of British Columbia, noted that climate change is exacerbating the frequency and intensity of these marine heat waves.

The blob is characterized as a large-scale marine heat wave that first appeared in 2013. It was caused by a persistent ridge of high pressure, which created a warm, nutrient-poor body of water stretching from Alaska to the coasts of British Columbia and Mexico. Nick Bond, a climatologist at the University of Washington, coined the term "blob" to describe this phenomenon. The previous blob lasted until 2016 and had devastating effects on marine life, leading to significant declines in populations of sea stars, fish, dolphins, turtles, seabirds, and shellfish. Additionally, the warming waters contributed to harmful algal blooms, which have recently impacted California's marine ecosystem, resulting in the deaths of numerous sea lions and dolphins.

The National Oceanic and Atmospheric Administration reports that the last six years have seen significant marine heat waves, with five of them being the largest recorded since monitoring began in 1982. Bond expressed concern about the potential permanence of these marine heat waves, stating, "Certainly, the temperatures are higher because of the overall warming of the ocean. The background warming of the ocean means when you get a spike then that’s on top of an ocean that’s already warming up."

Scientists are still investigating how these marine heat waves influence weather patterns. Bill Merryfield, a research scientist at Environment and Climate Change Canada, mentioned that more research is needed to understand the relationship between marine heat waves and weather changes. However, he suggested that the blob could lead to increased moisture in storms, potentially making atmospheric rivers more frequent and intense. He explained, "The atmosphere that’s in contact with the ocean will tend to be warmer, more water will evaporate from the surface of the ocean and tend to make moisture in the lower atmosphere as well."

The blob's impact on winter weather remains uncertain. Merryfield noted that the current blob is located farther from the B.C. coast compared to the one in 2015, which directly influenced warmer air over the Pacific Northwest. He stated, "In 2015, there was a pretty direct influence of the warmer air above the blob being carried over the Pacific Northwest."

Bond indicated that while the current marine heat wave was severe during the summer, it has since moderated along the Pacific Northwest coast. This moderation could be beneficial, potentially leading to a decent snowpack in the mountains of B.C., unlike the abysmally low levels seen in 2014 and 2015. He emphasized that this is positive news for both skiers and summer water supplies.

Climate change is contributing to the increasing intensity of marine heat waves, with many studies linking their rise to global warming driven by fossil fuel emissions. A recent study from the University of Victoria found that the blob is now seven times more likely to occur than it would have been before human-induced greenhouse gas emissions.

Looking ahead, scientists at Berkeley Earth predict a high likelihood of a La Niña transition between October and December, which typically brings cooler ocean temperatures and more precipitation to B.C.'s South Coast. However, recent La Niña years have been warmer than usual. Merryfield noted that this expected weak La Niña could lead to a wetter-than-normal winter due to the extraordinary warmth in the western and central North Pacific.

The blob's return raises concerns about its long-term effects on marine ecosystems. Harley warned that warmer waters could favor pathogens, leading to outbreaks of diseases like the one that has affected sea stars. He stated, "You can get big outbreaks of that wasting disease when the water is warmer."

Marine heat waves can disrupt natural ocean systems, impacting carbon cycling and potentially increasing greenhouse gas emissions. A recent study published in Nature Communications highlighted that ocean warming alters microbial community structures, affecting the production and transport of carbon-based organic matter in underwater ecosystems.

As the blob continues to influence the northern Pacific, scientists remain vigilant about its implications for marine life and weather patterns in British Columbia and beyond.