Atmospheric Chemistry

Objectives Know the components of the atmosphere. Discuss the different forms of electromagnetic radiation emitted by the sun. Understand how solar radiation interacts with the atmosphere (energy budget).

Atmospheric Gases 78%N 2 21% O 2 1%Ar variesH 2 O <1%CO 2 <1%CH 4 <1% ozone, O 3 (block UV) “greenhouse gases” trap heat

Solar Radiation UV Sunlight is mostly: ultraviolet, UV visible light, VL infrared, IR

Absorption of UV and IR Ozone absorbs UV CO 2 and H 2 O absorb IR

Energy Budget IR heats air; emits to space as IR VL reflects back to space; or heats surface and IR emits to space ozone converts UV to IR, emits to space energy in = energy out global temperature stays fairly constant IR VL UV

Objectives Understand how CO 2 affects global temperature. Understand how ice core samples show a relationship between CO 2 and temperature. Be familiar with modern data regarding changing atmospheric conditions. Know which countries/regions produce the greatest quantities of CO 2.

Global Warming fossil fuels: coal, oil, natural gas fossil fuel + O 2 → H 2 O + CO 2 greenhouse effect: gases such as CO 2 or CH 4 absorb IR, act like a blanket, and keep the atmosphere warm global warming: too many greenhouse gases result in a warming effect (like adding more blankets) global dimming: more clouds (from heating and smog) reflect VL, result in a cooling effect warming > cooling 97% of climatologists say humans play a role in global warming. U of Illinois-Chicago Survey U of Illinois-Chicago Survey

Ice Core Data source: IPCC Trapped air in ice cores reveal CO 2 levels. Low levels of oxygen-18 in ice = lower temperatures. CO 2 and temperature are closely related.

Ice core samples taken from two locations 650 km apart show data is credible

1 kg of gasoline makes 3 kg of CO 2 Increasing CO 2 Levels US Dept of Energy CO 2 levels up from 315 to 397 ppm (up 26%)

Global Temperatures

Temperature Change average up about 0.8 o C most warming in polar regions

Objectives Be familiar with the United Nation’s IPCC projections for future global surface temperature and sea-level values. Understand the affects of sea-level increases on coastal regions. Be familiar with environmental changes that are currently occurring in polar regions.

CO 2 Level

Observations and Projections

Temperature Rise 2100: 2 – 3.5 o C warmer (3 – 5 o F)

Observations and Projections

Sea-Level Rise 1 m 2100: 0.3 – 1.0 m higher

Greenland Greenland’s ice is melting five times faster than 1990s rate. (Science, 2012)

Arctic Perennial Ice perennial arctic ice cap is 50% smaller than 1980 less ice = less reflection = more absorption = more warming

A Warmer Montana… According to Montana DEQ: reduced snow pack—less water for irrigation and hydroelectric power; reduced water quality; ski industry will be affected milder winters! changes in crop yields (some up, some down) longer/drier forest-fire seasons changes in wildlife habitat—may affect hunting and fishing, tourism Climate Change Montana