Despite Republican assertions of climate change being a conspiracy theory, global mean temperatures are rising. In the Pacific Northwest(PNW) this warming trend will result in a shift in precipitation from snow to rain.
In research recently published in the Journal of Hydrology and Earth System Sciences, OSU scientists have modeled the effects of a 2°C rise in temperature, the amount of warming predicted by the International Panel on Climate change, on the Mackenzie River Basin(MKB) and their predictions are staggering to say the least.
As everyone knows arable land is second only to water in importance for modern agriculture and ranching. Oregonians know this better than most and with recent rulings giving back the Klamath tribe their water rights, irrigators are more concerned than ever with how they will maintain their fields and feed their livestock throughout the dry summer months.
Some 60 to 80% of the summer flow in the Willamette River originates as maritime snowpack in the Oregon Cascades. Water is “stored” during the winter in the MRB and as it melts during the summer months it supplies nearly a quarter of the river’s discharge.
Snowpack between the elevations of 1000 meters and 2000 meters is particularly sensitive to increases in temperature. When they used their model, which is considered predictively accurate, to determine the effects of a 2°C rise in temperature, peak snowpack occurred 12 days earlier than usual and there was 56% decrease, in volume, of snow water storage due to shifts in precipitation. They also applied their model to snowpack in regions above 2000 meters, which did benefit from increased precipitation, but the temperature rise still resulted in a decrease of 49% of snow water storage.
The researchers said that, “Mountain snowpack is a key common-pool resource, providing a natural reservoir that supplies water for drinking, worship, hydropower, agriculture, ecosystems, industry, and recreation for over 1 billion people globally.” As the global mean temperatures rise, less precipitation will fall as snow at lower elevation, leading to increased river flows and thus flooding during winter and spring, while also leading to decreased water availability, because of diminished snowpack, during the summer months.
By William Tatum