Natural causes of Climate Change

Astronomic forcing- changes in position of Earth and sun, Milankovitch cycle, Difference in solar radiation

Atmospheric forcing- change in composition of natural atmosphere such as volcanic eruption releasing aerosoles such as CO2, ash and dust. The atmosphere can block at solar radiation

glacial- ice sheets expand/advance

interglacial- ice sheets retreat

Eccentricity- 100,000 years

Obliquity- Axial tilt 21-41 000 years

Procession of the equinoxes March and September 26 000 years

Eccentricity 100,000 years

Elliptical orbit perihelion is shortest distance to sun and aphelion is greatest distance

greastes seasonal differences- interglacial increase in melting (ablation)

annual ice deficit

further solar radiation has to travel the greater the loss therefore cools the earth

Circular orbit

even seasons - glaial

even distrubiton of solar radiation- relatively warm air

increase temperatures

increase in evapouration

increase in mositure therefore increase in snowfall

Axial Tilt- determines the severity of seasons

24.5 - greater angle of tilt- increase in temperature, differences between the poles nad the equator, uneven distrubtion of solar radiation, interglacial

21.5 smaller angle of tilt- solar radiation even distrubtion, ice advance glacial, warmer air more mositure, more snowfall, ice growth extends from the poles to the equator- postive feedback ice grwoth means decrease in temperature

Precession of the equinoxes 26,000 years

12 1/2 000 years move away from Polaris to Vega

SUmmer temerpatures are more influential

When Earth is pointing to…