Scientists and environmentalists have been debating the issue for years. Are droughts the result of man-made carcinogens lofted into the air by way of the Industrial Revolution, or are they part of natural weather patterns witnessed by man for the past 200,000 years?
It may be a combination of both. For California during the past four years, a recurring high-pressure ridge off the West Coast and influenced by varying sea surface temperatures has blocked wet-season storms during this period, resulting in the least winter precipitation since 1974-77 for the world’s eighth largest economy. Researchers at Columbia University’s Lamont Doherty Earth Observatory and International Research Institute for Climate and Society, as well as the folks at NASA and at the National Oceanic and Atmospheric Administration this week reported that alleged human-induced climate change is not the sole reason why we’re receiving so little rain of late, this week’s storms notwithstanding.
While atmospheric models project that the southwestern portion of North America, as a whole, will become more arid because of rising greenhouse gas emissions, climatologists say a full determination of the impact of human-induced climate change from the observational record is very difficult.
“Observed trends, even over very long time periods, could arise from natural variability,” the study said. Examples in the region, the aforementioned scientific entities found, include serious droughts in the 1930s (the “Dustbowl”) and in the 1950s, as well as another round of serious drought since the 1970s to today.
“Precipitation trends computed amidst such a rich record are most likely heavily influenced by natural variability,” the researchers said. Basically, they have determined, Mother Nature shall have her way whether man contributes to climate change or not.
Of three other studies published recently by the American Meteorological Society, only one argued that climate change may have played a role in the drought. But climate models don’t support that conclusion, because they suggest a low-pressure system should naturally develop off the coast of California, rather than the high-pressure system that actually did. Columbia University researcher Richard Seager, co-author of the report, told reporters this week that rampant greenhouse gas emissions witnessed for about 40 years worldwide probably have had little to do with climate change.
“We are saying that climate change would have not been a main driver of the precipitation anomalies, which was the fundamental cause of the drought,” Seager said. “California lost essentially one full year of precipitation.”
However, some scientists have said the report does not take into account the continual warming of the atmosphere which is related directly to greenhouse gas emissions which in turn, have exacerbated the natural climate variations. Basically, greenhouse gas emissions have worked to “speed up” what nature does naturally over the course of centuries.
The latest findings, however, are unlikely to temper the push by federal and state regulators and environmental groups to further curb power-plant carbon emissions to reduce the threat of climate change in California and elsewhere in the country. The Environmental Protection Agency has proposed existing power plants cut carbon emissions by 30 percent from 2005 levels by 2030. The EPA also recommends that California do more to capture valuable storm runoff. Most of the water that California uses in the spring and summer to grow crops, water lawns and hydrate people and livestock arrives in the winter—ususally in February—and that means it needs to be captured in reservoirs as it falls or it has to come as snow. According to the report, winter 2013-14 in California was the sixth-driest since records began in 1895, and the three-winter average precipitation from 2011-14 was the second lowest, behind 1974-77.
As to the current storm, flooding taking place today statewide may provide an indication that regular rainfall may be on its way, say scientists. Another storm is set to arrive on Monday giving Californians hope that they can emerge from the worst drought in 1,200 years. This weekend’s storm and the one to follow throughout much of next week may deliver gallons of water per square mile. Ken Clark, a meteorologist with AccuWeather.com, said the storm is going to be “such a soaking rain.”
In recent burn areas, mudslides can be expected, as well as rock slides and continual flooding. In the Sierra Nevada Mountains, snow levels may drop below the Donner Pass and fall below 7,200 feet. Snow is expected to fall at close to one foot per hour, resulting in whiteout conditions.
