It’s Science Wednesday! Yesterday, Ricardo and I went up Colorado’s 5th highest mountain: La Plata Peak (14,336 ft./4370 m). The trail conditions were very challenging below treeline, as we had to break trail through very loose and unconsolidated dry snow with our technical snowshoes (more photos on that coming in a separate post). While up high on the mountain, I took the opportunity to collect a snow sample near the summit, at 14,300 ft. My current (remote) work with the University of Alaska includes co-teaching a “dirty snow science” class for students in Alaska – for them to learn how to sample local snow in order to understand and learn first-hand how particulates (like dust and soot) can affect melt rate of the snow.
Dust can come from de-vegetated or dry soils due to land use changes. Black carbon (soot) is formed by the incomplete combustion of fossil fuels and wood. Complete combustion would turn all carbon in the fuel into carbon dioxide (CO2), but combustion is never complete and CO2, carbon monoxide, volatile organic compounds, organic carbon and black carbon particles are all formed in the process. Black carbon is a short-lived climate pollutant with a lifetime of only days to weeks after release in the atmosphere. However, during this short period of time, it can have significant direct and indirect impacts on the climate, the cryosphere (snow and ice) and human health.
Black carbon is an important contributor to warming because it is very effective at absorbing light and heating its surroundings. The dark contaminant absorbs more solar radiation, much like you do when wearing a dark versus light t-shirt. When deposited on ice and snow, black carbon reduces surface albedo (the ability to reflect sunlight) and heats the surface instead, leading to enhanced melting.
When suspended in the atmosphere, black carbon contributes to warming by converting incoming solar radiation to heat. It also influences cloud formation and impacts regional circulation and rainfall patterns.
I’m currently letting the snow sample from La Plata melt naturally (while in the field, we melt down the samples over a stove) and then will filter it, to see how many particulates are present. As the students will be collecting some of their first samples and sharing their results early next week, it will be interesting to compare what we all find in our respective geographical regions!