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NW Fishletter #392, April 1, 2019

[4] Experts: As Climate Warms, Orcas Will Feel Impacts On Many Levels

The Southern Resident Orca Task Force heard dire warnings from experts on how continued climate warming is expected to impact the whales.

The group began its second year of work March 18 to develop long-term recommendations to save the endangered Puget Sound whales.

Climate change is expected to increase the severity of stresses that orcas and salmon are already experiencing, the group was told. As temperatures continue to rise, the whales will face a whole host of issues, including warmer water, higher sea levels, less snowpack, a changing runoff schedule, more water pollution and sediments, and more difficulties with echolocation. And the only way to prevent temperatures from going up forever is to achieve "net" zero greenhouse gas emissions, experts said.

During the meeting's afternoon session, Amy Snover, director of the University of Washington's Climate Impacts Group, told the task force that the orcas' ability to survive the effects of a changing climate will be determined by the choices we make today.

"This choice is about energy use," she said, noting that the type of fuels we use now will determine how much warming occurs. Their survival will also depend on whether and how we plan for "the climate we know is coming, not the climate we used to have."

After hearing about the serious challenges of global warming, the vast majority of people providing public comments at the end of the meeting called for removing the four lower Snake River dams, despite the impact that would have on greenhouse gas emissions. It was the only message from some of those who commented, and one of five "key actions" that several environmental groups asked the task force to take this year.

The four dams currently produce about 1,000 average megawatts of power. According to a Bonneville Power Administration fact sheet, replacing their energy with natural gas generation would increase carbon dioxide emissions by between 2 million and 2.6 million metric tons, equivalent to emissions from 421,000 cars.

NW Fishletter reached out to Snover to ask if the Climate Impacts Group has a position on removing the dams. In an emailed response, Snover confirmed that the sooner the world can drop to "net zero" greenhouse gas emissions, the less warming that will occur. Net zero emissions pathways generally assume drastic reductions in emissions, with continuing emissions offset by the removal of carbon from the atmosphere through methods like reforestation or carbon capture and storage.

"Hydropower is essentially carbon-free power, which is what we need," Snover wrote. However, she added, in order to ensure that orcas and salmon not only survive but thrive in the future, we will also need to reduce the current threats they face.

"Exclusively from the climate point of view, there are arguments for both keeping dams and for removing them," she wrote. "Do we do good in the short term (by focusing on improving habitat) while jeopardizing the long term (by eliminating a carbon-free source of power)? If we focus on the longer-term durable solution (transition to a carbon-free energy system), do we risk loss of what we're trying to save (because they can't survive both current threats and unavoidable impacts of climate change)?" she asked.

Snover added, "This type of situation, in which there are no easy answers and lots of complicated trade-offs, is the hallmark of climate change." She concluded, "In my opinion, one of the most urgent things for us to do is to come together as a society to examine the whole complexity of issues, like orca recovery, and engage in (small 'p') politics--discussing, identifying and negotiating priorities and solutions across multiple interests with our eyes wide open to the challenges we face and the consequences of both our actions and our choices not to act."

In front of the task force, Snover and Terrie Klinger, also from the Climate Impacts Group, described some of the impacts of climate change.

Klinger said two things are happening in the ocean as a result of greenhouse gas emissions. First, the ocean is absorbing some of the atmosphere's carbon dioxide--it has already taken in 31 percent of the carbon dioxide that has been emitted by industries and deforestation--causing ocean acidification. A more acidic ocean leads to harmful algal blooms. Studies have shown that under these conditions, coho experience a diminished sense of smell, which is needed to recognize the presence of predators.

Acidification also interacts with certain metals, causing added physiological effects to organisms exposed to them. Also, low-frequency sounds travel significantly farther with ocean acidification; so while the orcas' sounds may travel farther, they're also more likely to hear the low-frequency sounds from boats that impede their communications, Klinger said.

The emissions are also causing ocean temperatures to warm, she said. Studies have shown that salmon may require more food at higher temperatures, and many studies have shown that, at higher temperatures, ocean organisms are more sensitive to the same degree of ocean acidification, she said.

Snover outlined many of the freshwater impacts to rising temperatures. Salmon--which are adapted to specific timing of snowmelt--will see changes in the timing and levels of runoff, she said. Salmon eggs and juveniles will be threatened by higher high flows from heavier rainstorms and faster snowmelt. Adults and juveniles will be impacted by low flows, which are expected to become more acute. Water temperatures will increase even more under low flow and hot weather conditions, she noted.

She also said that a rising sea level will cause a permanent loss of some coastal habitat and inundation of estuaries. There will be more sediment in streams, as glaciers recede and exposed glacial rubble is washed downstream, and as flooding from heavier rainfall releases more sediment. More chemicals and pollution will be drawn into the aquatic system, both by rising sea levels that inundate industrial sites along the shoreline, and flooding streams.

Snover noted that globally, temperatures have already increased by 1 degree Celsius, or 1.8 degrees Fahrenheit.

She said even an increase to 1.5 C, is significant, as outlined in a recent Climate Impacts Group report.

Among the impacts that will affect salmon and orcas: the number of very hot days--those above 90 degrees--in Washington state will increase by 67 percent; the April 1 snowpack will drop by 38 percent; streamflows will increase by 16 percent in the winter and drop by 23 percent in the summer; and sea levels will rise by 1.4 feet by 2100.

While many of the ways that a warming climate will affect the orcas and the salmon they depend on are known, "It's an open question right now about how much and how fast the climate will change," Snover said. "That's because the uncertainty's on us--on us as a society."

She noted there are ways to limit rising temperatures to 1.5 degrees Celsius, but global emissions must start to decline well before 2030.

"The way I interpret it is, there are 12 years left before these really steep near-term reductions must be occurring so that we can be on a path towards net zero by 2050," she said. "A degree and a half matters, but we're on track to much more than that."

If greenhouse gas emissions continue at current levels, Snover said temperatures are expected to increase by a total of 3 degrees Celsius (5.4 degrees Fahrenheit) by 2050, and by 6 or 7 degrees Celsius (10.8 to 12.6 degrees Fahrenheit) by 2100. -K.C. Mehaffey

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Publisher/Editor-in-Chief: Mark Ohrenschall, Editor: K.C. Mehaffey
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