Early Warming. Nancy Lord

on it and since 1998 had been monitoring twelve sites on four Kenai Peninsula salmon streams for pollutants, along with water temperature, pH, dissolved oxygen, turbidity, and nutrients.

      The biggest surprise was finding that in recent summers stream temperatures on the lower Kenai often exceeded state water-quality standards set to protect salmon spawning and the survival of eggs and fry. And water temperatures were trending upward, tracking air temperature increases.

      Here at the Ninilchik River, the number of summer days that water temperatures had exceeded state standards for the upper limit of egg and fry incubation (55.5 degrees Fahrenheit) increased from fifty-six days in 2002 to seventy days in 2005. The number of days that the standards for the upper limit for fish migration and spawning (59 degrees) were also high—to more than fifty days. Other Kenai Peninsula streams showed similar temperatures and trends. In 2005 the Anchor River close to Homer topped the 55.5-degree limit on eighty-eight days and the “do not exceed” temperature of 68 degrees on six days.

      Mauger is well aware that a few years of data mean, by themselves, very little. (In fact, in the couple of years after 2005, the stream temperatures were a little less alarming, before shooting back up in 2009.) She also knew that increased stream temperatures could be due to a number of factors. Like a detective, she’d set out to discover associations and meaning.

      Stream temperatures can increase as a result of land development—the cutting of shade trees, paved surfaces where water warms before running off, water withdrawals. It was true that much of the spruce forest on the Kenai Peninsula had died from a beetle infestation, but an analysis of the subsequent logging that occurred on different watersheds, with changes in stream shade, could not account for the warming. Neither could the very small amount of development that dotted woods and fields with cabins and connected them by roads and trails.

      What did correlate with the warming streams was warming air. At the Homer Airport, air temperature records go back to 1932—a long time for Alaska, where most baseline data is sorely lacking. Those records show that most of the warming has occurred since 1977, following worldwide trends, with summer air temperatures warmer by two degrees Fahrenheit and December and January temperatures by four degrees. Beginning in 2005, Cook Inletkeeper started hanging temperature data collectors in trees near the stream data loggers and found that the water temperatures generally tracked the air temperatures. That is, when we have a warm summer, the water temperatures are warmer, and when we have a cooler summer, the water temperatures are cooler. (The relationship also changes with water volume, which relates to the amount of rain and snowmelt.) With that relationship established, Mauger and others can “backcast” to estimate earlier stream temperatures as well as begin to predict future stream temperatures if air temperatures continue to rise.

      We were not, Mauger emphasized to me, at temperatures where we were seeing any visible changes in survivorship. That is, fish were not dropping dead in the streams. The effects could be more subtle—stress that might affect growth or susceptibility to disease. It was time, she said, before we had catastrophic results, to “get people comfortable with using the data. The trajectory that we’re on gets us there. What we don’t know is the time scale.”

      Mauger had, in the last couple of years, begun making public presentations about her work to various audiences.¹ She’d presented at science conferences and to conservation groups, to chambers of commerce and fishing organizations. In 2007 she’d been an invited guest to speak to the Alaska Climate Impact Assessment Commission appointed by the state legislature. The commission, a “balanced” group of government employees, industry representatives, and citizens, included members who did not believe that human activities contributed to global warming, and Mauger described the group as “a little bit of a hostile audience.” (One person in particular wanted to argue the science with her, and others accused her of having “no proof” that salmon were being affected.) As we turned back from the river, Mauger half grimaced, half chuckled. “I didn’t feel like I had a very aggressive message, so I was kind of surprised by the feedback I got.”

      Her recommendations to the commission, about what should be done in Alaska, had been straightforward:

      1. Collect stream temperature and flow data in key watersheds across the state.

      2. Incorporate temperature data (both stream and marine) and climate information into salmon management models and plans.

      3. Encourage actions to increase watershed resiliency to climate warming.

      One of the points she tried to make in all her presentations was, she acknowledged, the need to control greenhouse gas emissions. But even if we stopped burning fossil fuels immediately, past actions had already committed us to a certain amount of environmental change, and she wanted people to think about what that meant. “We need to understand what that change is going to look like on small, regional scales,” she explained. By starting to collect stream temperature data, “we’re helping communities understand what role fishing will play in their future. This project is about getting people the information they need to make good economic decisions.” It was up to those people, then, to decide what they wanted to do, both to ameliorate the negative effects of climate change and learn to live with them.

      Mauger and I returned to Inletkeeper’s Ford hybrid and drove the short road down into the village of Ninilchik. There, a huddle of homes crowded the lowest bend of the river and a small boat harbor accessible only at the highest tides.

      Ninilchik has a unique history among Alaskan towns, having been settled as a retirement colony for Russians and their “creole” families (the results of Russian and Alaska Native unions) who chose to stay in the country when control passed from Russia to the United States in 1867. Many of the residents today are direct descendants of those settlers, and the onion-domed Russian Orthodox church on the hill is surrounded by a graveyard filled with more of those Russian names. From where we stopped by the river to check a stream gauge, I spotted the notched-log house once owned by a friend, who, when he stripped the inside for a bit of modernizing, found old Russian newspapers used as insulation. The Russian colonists, the Dena’ina Athabascan people who preceded them, and all comers since have relied on the river and its salmon for their lives and livelihoods. It was unthinkable that the people of Ninilchik should have to turn away from that history and dependence.

      What does it mean when stream temperatures exceed state standards for salmon spawning and rearing? Nobody quite knows. Alaska’s temperature standards are actually a modification of research-based recommendations from the Pacific Northwest, not based on any Alaska-specific data—and not adjusted regionally to match Alaska’s huge geographical spread. A former governor, Frank Murkowski, had eliminated the Department of Fish and Game’s Habitat Division, so there was no one home to figure out what effects, if any, warmer temperatures might actually be having on Alaska’s wild salmon.

      We do know, from testing and experience elsewhere, that higher temperatures can have profound effects on salmon and other cold-water fish. Higher temperatures can reduce growth rates (when fish have to put more energy into respiration and metabolism), reduce the survival of eggs and fry, affect the timing of out-migration (reducing marine survival), increase disease, and make fish more vulnerable to pollution (since some chemicals and metals increase in toxicity with higher temperatures). Warmer waters can also influence food supplies, vulnerability to predators, and competition with other species including exotics that move into waters made more hospitable to them. And we do know that when fish (and living organisms generally) are stressed by any one process, they’re less able to deal with other stressors.

      Along the West Coast of the United States, salmon runs have been in serious decline, with the collapse of California’s Sacramento River Chinook runs resulting in a complete closure of sport and commercial salmon fishing off the coast of California and most of Oregon. The reason for the collapse was not clear. Some biologists pointed to unusual weather patterns that disrupted the upwelling of nutrient-rich water in coastal waters that normally supported the marine food web. Other people pointed to water quality issues related to damaged habitat, agricultural pollution, and altered flows and temperatures related to development and water diversions. Greenhouse gas-induced climate change might be just one factor among a series of environmental insults.

      In