Lecture 4 Global climate change

The basic theory of climate change

1. Light energy and UV radiation from sun warms earth’s surface

2. Earth is heated and the surface reradiates long wave radiation

3. Greenhouse gases trap some long wave length energy as it leaves the planet

Main greenhouse gases

N₂ 78%

O₂ 21%

H₂O 0-0.02

CO₂ 422 ppm

Layers + Pauses of atmosphere

Exosphere

Thermosphere

Mesopause

Mesosphere

Stratopause

Stratosphere

Tropopause

Troposphere

Jean Baptiste Fourier

1827 he proposed greenhouse effect. Heat trapped, some leaves

John Tyndall

1860 discovered infrared light was absorbed by CO2 and H2O

Svante Arrhenius

1896 estimated that a doubling of CO2 would increase global temp by 5-6 degrees. Speculated CO2 doubling

Guy Callendar

1938 proposed Earth warming due to anthropogenic CO2 from burning fossil fuels

Determined surface temps already increased

Charles David Keeling

1958 Started measuring global CO2 levels from top of mauna loa. Showed the increase over years of CO2

Fossil Fuels

Gasoline, coal, natural gas

According to milankovich cycles, what is the climate supposed to be doing

Earth should be cooling because of general temp trends

Natural sources of methane

Wetlands- methanogenic archaeans

Released from cows and termites

permafrost melting

methane clathrates melting in ocean

Anthropogenic sources of CH4

Leakage from oil mines

Cattle belch

landfill sites

waste treatment

Anthropogenic source of CFC

Refrigerants and aerosols

Anthropogenic sources of Ozone

Car smog

Anthropogenic sources of N₂O

Fertilizer