It’s not easy to see aerosols in Earth’s atmosphere,
but they’re there.
And NASA scientists say these tiny particles
are having a profound effect
on snowpack and spring climate in the Northern Hemisphere.
At any moment, millions of tons of aerosols lifted by winds
and generated by wildfires and the burning of fossil fuels
are traveling across the globe.
In snow-covered regions,
certain kinds of aerosols can darken the snow and ice
causing it to absorb more of the sun’s energy and melt faster.
Scientists call this phenomenon the snow darkening effect.
The snow darkening effect is basically another way of saying
what happens when snow gets “dirty.”
Snow that has become darkened by aerosols
absorbs more sunlight, than snow that is pristine.
This may not seem significant,
but it can actually have a big effect
on the melting during spring.
Using a NASA climate model,
researchers studied the impact of three types of aerosols
on snowpack in the Northern Hemisphere spring,
specifically dust, black carbon, and organic carbon.
The areas colored red to purple on this map
show where the surface absorbed more energy from the sun
due to snow that has become darkened by these aerosols.
This surface warming resulted in
reduced amounts of snow in spring,
shown here in areas colored blue.
These reductions might reflect an earlier melting of winter snowpack
and ground warming of areas normally covered by snow.
In some places,
temperatures are up to about 10 degrees Fahrenheit warmer
than it would be if the snow were pristine.
As we add more of these aerosols to the mix,
we are changing the makeup of particles in the air and snow,
potentially increasing our overall impact on Earth’s climate.