Editing Earth's Energy Budget (section)

== The Role of Albedo and Reflection ==

Not all of the 340 W/m2 of incoming solar energy enters the climate system to heat the planet. A significant portion is immediately bounced back into deep space.

'''Albedo''' is the scientific term for the reflectivity of a surface, expressed as a fraction or percentage. An albedo of 0.0 (or 0%) means a surface absorbs all incoming light (a perfect blackbody), while an albedo of 1.0 (or 100%) means a surface reflects all incoming light (a perfect mirror). 

On average, the Earth System has a planetary albedo of roughly 0.30, meaning about 30% of incoming solar radiation is reflected directly back to space. This reflection occurs at several levels:
* '''Atmospheric Reflection:''' Clouds are highly reflective. Thick stratocumulus clouds can reflect a massive amount of shortwave radiation. Additionally, suspended particulates and aerosols (such as volcanic ash or sulfates) scatter incoming light.
* '''Surface Reflection:''' The cryosphere plays a critical role here. Fresh snow and thick ice sheets have an albedo ranging from 0.70 to 0.90. Conversely, open ocean water is highly absorptive with an albedo of less than 0.10, and dark terrestrial forests typically range around 0.15. 

Because of the stark contrast between the albedo of ice and the albedo of open ocean, the melting of sea ice triggers a powerful positive feedback loop: as ice melts, it reveals dark ocean water, which absorbs more solar energy, leading to further warming and more ice melt.