Planetary Albedo
The albedo or reflectivity of the Earth's surface affects the planet's heat budget and thus the climate of the planet. Things such as, but not limited to, aerosols, clouds, ice, snow, water, land, plant surfaces, asphalt, and concrete all contribute to the Earth’s albedo. Aerosols are small airborne particles that can be derived from natural environmental sources – for example, volcanoes, wildfires, windblown soil dust, land and ocean emissions of biologically produced gases, and sea-salt spray – or they can be emitted from human sources – for example, spray cans, industry, etc. The size and distribution of the aerosols determine whether the surface temperature of the Earth increases or decreases. Generally, the larger the number of aerosol particles, the greater the aerosol cooling effect due to the increased amount of heat radiated or reflected back to space. Aerosols will be discussed in more depth in the next section of Chapter 2 - B. Greenhouse Effect.
Ice and snow surfaces have a very high albedo. When sunlight strikes ice or snow, most of the light and heat energy is reflected. Assuming other factors influencing climate are held constant, the greater the area of Earth’s surface covered by ice, snow, glaciers, sea ice, etc. the more energy is reflected back to space and the cooler the planet's climate. Deserts and other non-vegetated areas have albedos less than that of ice and reflect only half of the radiation they receive. Liquid water in oceans and lakes has a very low albedo and absorbs most of the radiation received and is warmed in the process. Land and aquatic plants absorb almost all incoming radiation. An increase of vegetation coverage with all other climate factors held constant would lead to an increase in the temperature of the planet.