Sunday, May 25, 2014

Cloudbursts and Climate Changes

    This spring we’ve heard of terrible floods on the Florida panhandle, terrifying tornados in the Midwest, fierce and way too early wildfires in Alaska, California, and Arizona. But we Pacific Northwesterners count ourselves fortunate to live where we live. We seldom have natural disasters to worry about.

    Or do we? We have summer wildfires. We have a vague awareness that the volcanoes looming on our horizons aren’t really extinct. Now and then, the earth shrugs its shoulders and an earthquake reminds us that a “big one” lurks on a known or unknown fault line. Signs along our coastline point out tsunami escape routes to use if the ocean should overrun its bounds. And when it rains a lot, we can have landslides.
  It rained a lot in Marysville last Sunday. A storm cell packed with water, thunder, and lightning sat for two hours over part of the city and let loose the hardest cloudburst that people who’d lived there all their lives could remember. The Everett newspaper, the Herald, called it a “a 100-year event.” Marysville storm sewers are designed to accommodate a 25-year, 24-hour rain totaling 2.75 inches. A 100-year event would be 3.36 inches in 24 hours. On Sunday, May 18, 2014, in the space of two hours, the rainfall officially totaled 3.40 inches.

    My brother lives in one of the neighborhoods that received the deluge. He and his wife listened to rain pound the roof as the street filled up with water. Then they realized that water was pouring in a waterfall the length of the gutter. The newly-installed screens meant to keep leaves and tree needles from clogging the downspouts were blocking the rainwater. Bill grabbed his rain gear and a tall metal ladder, and despite painful arthritis, climbed the ladder, removed a screen, then went inside to change his drenched clothes. By that time, more gutters were overflowing and back he went into the downpour as thunder crashed and lightning streaked across the sky. After two more changes of clothes, he’d diverted water from running into the daylight basement, although it flooded the garage floor. Rainwater stood three to four inches deep in his driveway when the rain finally stopped.

    As a hobby, Bill has kept a rain gauge and recorded daily totals for 25 years. For those two hours, his gauge recorded 4.61 inches of rain; more than the total for any May over the past 25 years except for May of 1988, which had 4.72 inches.

    The National Weather Service says evidence suggests a trend in Western Washington toward higher-intensity, shorter-duration rains in spring and fall. Is this a sign of climate change?

    Perhaps. Anyone who studies geology or history can point to recurring cycles of weather change. Some of those unique events have happened within the lifetimes of some still living, including the big snow of 1914.  More than 30 inches of snow fell in Everett in 36 hours, but nearby areas reported even more. Snohomish had 42 inches and Marysville, 48 inches. That was also the year the Stillaguamish River froze over. Even in the 1940s and 1950s, local winters were much more severe than they are now.

    In prehistoric times, the valleys of the North and South Forks of the Stillaguamish River were blocked by a lobe of the Cordilleran ice sheet. This caused lakes to form in the valleys. They dropped layers of sediments that became today’s unstable soils. It was those unstable soils that led to the recent landslide at Oso.

    We hear a lot about melting glaciers and warming winters, both in our mountains and in Alaska. My friend Jeanne and her brother Jonathan flew to Kako, Alaska from Anchorage earlier in the week. One hour of the three-hour trip by bush plane took them over the Alaska Range. Jeanne said, There are usually “snow capped mountains and glaciers in every direction as far as our eyes can see. This year, however, some of the snow has melted, and even some of the glacier ice has melted due to the warm winter and spring. Jonathan showed me one place that had held a glacier and is now empty, and said, ‘A glacier has been there as long as I can remember, but now it is gone!’”

    Scientists in polar regions are concerned about the melting sea ice.
    Spring is coming earlier and snowfall is not as heavy as normal.

    Observation in our area tells us that’s true here, too, although our Midwest and Eastern friends and relatives complain with reason about unusually severe storms and long-lasting winter weather.

    It’s fascinating to pay attention to the small things that are out of the ordinary. Maybe they’re just blips in the natural history of this area, but here are a few things that are different in our little corner of the country:

    Tent caterpillars in February: I found a couple of nests of the wriggling creatures in the arborvitae hedge and disposed of them when it was still winter. I never saw them so early and never saw them eating evergreens.

    Other voracious insects: Warmer winters and earlier springs encourage insect infestations. Something is turning the leaves on our vine maple to lace. Beetles have killed vast acreages of evergreens in Canada’s mountains and now they’re attacking our Cascade evergreens.

    Early blooming flowers: Usually we have armloads of lilacs to take to the cemetery on Memorial Day. This year my lilacs and irises are already through blooming.

    Ocean Acidification: Increased carbon dioxide from burning fossil fuels dissolves into the ocean and is killing off sea creatures such as coral, whose skeletons are based on calcium carbonate. In recent years, reproduction of the famed Willapa Bay oysters has been wiped out because of the acidification of ocean water along our coast.
    Since our early ancestors migrated from Asia to the Americas, people have adapted to changing conditions. We can adapt, too. I just hope that we humans will soon discard the practices that hurt the earth we share, for the sake of those who will live here after us.
Photo courtesy of blog, New Dharma Bums