PSY320H1 Lecture Notes - Lecture 9: Polar Regions Of Earth, Sea Level Rise, Volcanism
Lecture 9
Ozone (O3)
• Pollutant in troposphere
o O3 major component of photochemical smog
• Essential in stratosphere
o Stratospheric O3 absorbs 99% of incoming UV radiation
• Ozone thinning occurs annually above Antarctica (naturally)
o Causes: CFCs
• Measured in dobson units
• Global ozone depletion causes skin cancer, harms crops and Primary productivity
Ozone Thinning and Polar Spring
• During the polar winter, the cold temperatures lead to the formation of polar stratospheric
clouds;
o Rxns in clouds convert the reservoir forms of the ozone destroying species (i.e. CFCs) to their
molecular form. When the sunlight returns to the polar region in the southern hemisphere
spring the Cl2 is rapidly split into chlorine atoms which lead to the sudden loss of ozone.
Effects of Ozone Depletion
• More UV radiation reaches Earth
• Damage to ecosystems
• Human health problems; skin cancer, cataracts, weakened immunity
• Montreal protocol in 1987 aimed to reduce CFCs (reduced by 50%)
• The ozone layer is beginning to recover and full recovery will be possible by 2050
Climate Change
• Climate = a area’s log-term atmospheric conditions
• Weather = conditions at localized sites over hours or days
• Global climate change = describes trends and variations in earth's climate
• Enhanced global warming - the rapid climatic changes taking place due to human activities: fossil
fuel combustion and deforestation
Many factors affect climate change
• changes in solar radiation
o Albedo
o Solar energy fluctuations (i.e. orbit & sunspots)
• GHG
• Ocean circulation changes
• Catastrophic events such as volcanic eruptions
• Tectonism
• Biosphere - photosynthesis & ocean biological pump
Solar Radiation & Climate
• Albedo: a measure of reflectivity of a surface
o Clouds have high albedo, reflect solar radiation (cooling) also Aerosols generally have a
cooling effect
• Ice-albedo feedback is a positie feedak loop: tep rises → less so ad ie → ore sulight
asored lad ad sea → arer tep
The Sun & Latitude
• Temp varies with latitude bc the sun does not reach all placed uniformly
• Iliatio o its ais deteries Earth’s seasos
• Suns rays hit the N. hemisphere obliquely (at an angle) and more directly during the summer
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Document Summary
Ozone thinning and polar spring: during the polar winter, the cold temperatures lead to the formation of polar stratospheric clouds, rxns in clouds convert the reservoir forms of the ozone destroying species (i. e. cfcs) to their molecular form. When the sunlight returns to the polar region in the southern hemisphere spring the cl2 is rapidly split into chlorine atoms which lead to the sudden loss of ozone. Many factors affect climate change changes in solar radiation: albedo, solar energy fluctuations (i. e. orbit & sunspots, ghg, ocean circulation changes, catastrophic events such as volcanic eruptions, tectonism, biosphere - photosynthesis & ocean biological pump. Solar radiation & climate: albedo: a measure of reflectivity of a surface, clouds have high albedo, reflect solar radiation (cooling) also aerosols generally have a cooling effect. Ice-albedo feedback is a positi(cid:448)e feed(cid:271)a(cid:272)k loop: te(cid:373)p rises less s(cid:374)o(cid:449) a(cid:374)d i(cid:272)e (cid:373)ore su(cid:374)light a(cid:271)sor(cid:271)ed (cid:271)(cid:455) la(cid:374)d a(cid:374)d sea (cid:449)ar(cid:373)er te(cid:373)p.
