Albedo & Global Warming

Albedo is the technical term for how reflective the Earth is.
High albedo surfaces, such as snow and clouds, appear light or white in color and reflect a lot of the energy that comes from the sun in the form of light, both visible and non-visible. In contrast, low albedo surfaces, such as water, dark soil, and forests, appear dark in color and reflect very little of the sun’s light, absorbing the energy and heating up instead. Viewed from space, the Earth’s average albedo is around 30% [1], mostly due to atmospheric reflection by clouds and tiny particles in the air called aerosols [2]. In the past 200 years, human activity has modified Earth’s albedo in both directions: the conversion of forests to croplands has tended to lighten the surface, while urbanization has tended to darken the surface [3]. Increasing Earth’s reflectivity by making it lighter to reflect more sunlight out to space is a way we can counteract the energy imbalance in the Earth system that causes global warming [4]. Here are some of the best articles on the interaction between albedo and climate change:

RESOURCES

1. The Albedo of Earth (Stephens, O’Brien, Webster, et al, 2015)

2. Atmospheric and Surface Contributions to Planetary Albedo (Donohoe, A., and D. S. Battisti, 2011)

3. Anthropogenic Albedo Changes and the Earth’s Climate (Sagan, C., O. B. Toon, and J. B. Pollack, 1979)

4. Earth’s Energy Imbalance (Trenberth, K. E., J. T. Fasullo, et all, 2014)

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