The Continuing Albedo Change Warms the Earth More Than Twice as Much as CO2
13 hours ago Guest Blogger 100 Comments
Gabriel Oxenstierna
All life on Earth (somehow) originates from the Sun’s heat.
But how much of the solar irradiation reaches us Earthlings?
The question is highly relevant, as the amount of reflected sunlight displays a remarkable decreasing trend over time. As will be shown, this trend alone explains most of the warming we’ve had in recent decades.
The Earth’s reflectivity is measured by albedo (a latin word meaning ‘whiteness’). Albedo measures the proportion of solar irradiation that is reflected back to space, either by the ground or in the atmosphere. If albedo is 100 percent, all light is reflected, and 0 percent means no light is reflected. Albedo is very different for different materials: pure snow can be as high as >90%, dirty snow can be as low as 20%. Water has albedo <10% (depending on the angle of reflection, see figure 1).[1] Clouds vary greatly and are between 30% and 80% depending on the type of cloud. The Earth’s albedo averages 28%.
Figure 1. What reflects more sunlight, clouds, snow, ice, or water?
If we start from the top, we have a pretty much constant solar irradiance. As soon as the radiation enters the atmosphere, photons begin to be reflected by ozone in the stratosphere, by clouds, water vapor and aerosol microparticles. Of the remaining solar irradiation that reaches the Earth’s surface, an additional part will be reflected away. The amount that is reflected varies greatly and depends on numerous factors such as the geographical location, ground conditions (land/sea/rural/urban), which season we’re in, temperature, altitude, and not least the weather at the location.
https://wattsupwiththat.com/2024/03/05/the-continuing-albedo-change-warms-the-earth-more-than-twice-as-much-as-co2/
