Ch 7 – Global Change

Stratospheric Ozone
shields life on Earth from the sun’s UV radiation
Three forms of sun’s UV Radiation
__A (long wavelength), __B (medium wavelength), __C (short wavelength)
Ozone (O3)
formed in the upper stratosphere by photochemical reaction between O2 and O with UV as catalyst; UVC can break apart the O molecule; a reversible action; mostly produced near equator
photolyze
to break apart with light
Stratosphere
extends 6 mi to 31 mi above Earth’s surface; houses 97-99% of atmosphere’s ozone
Ozone in Troposphere
the small perentage of ozone that is considered a pollutant
Ultraviolet Light
light with wavelengths shorter than the minimum the human eye can see
Most Common Bands of Energy
Visible Light, Infrared, Ultraviolet
UV-A
wavelength of 320-400nm; most of it reaches Earth’s surface; closest to blue/violet in visible light spectrum; essential for making vitamin D & tanning; overexposure causes sunburn & premature aging; can be seen by birds, insects, and reptiles
UV-B
5% reaches Earth’s surface; 290-320nm; can alter human DNA; over-exposure causes “snow blindness,” cataracts, immune deficiencies, and non-melanoma skin cancer
UV-C
100-290nm; none reaches Earth’s surface; only found in the ozone; both forms and destroys the ozone
Ozone-depeleting substances
chemical compounds released into atmos that cause _____; contain chlorofluorocarbons and halogens (CL, Br, I, F) in the atmosphere
chlorofluorocarbons CFCs
primary man-made compounds involved in depletion of ozone; commonly used as refrigerants & aerosol propellants; now banned in US & most developed countrues; stay in stratosphere for 20-120 yrs
Ozone Hole
area of seasonal ozone depletion over Antarctic that tends to travel toward the equator and may linger over Australia, New Zealand, S. America, & S. Africa; increased UVB lvls by 3-10%, occasionally 20%
Polar Stratopheric Clouds (PSCs)
ice clouds formed during the Antarctic winter months of below -78C; consolidation of greenhouse gases in these clouds drive O3-depletion ractions
Chlorine Monoxide (ClO)
formed when UV radiation breaks down a CFC molecule and reacts with a disconnected O molecule from O3; one atomic Cl molecule can destroy 100,000 O3 molecules
Bromine
150x less than CL, but 10 to 100 times more destructive of O3; no stable binding of ___ and it is easily photoyzed
Environmental Effects of O3 Depletion
weather pattern changes; increasing cooling of strat & warming of tropo; more ground-lvl smog; increased sunburns, eye diseases, plants; incr’d UVB radiation; incr’d rate of mutations in human & nonhuman DNA
Hydrochlorofluorocarbons (HCFCs)
safe CFC alternative; replace Cl molecule with hydrogen; react with stratospheric O3 but they have shorter atmospheric lifetimes than CFCs; HCFCs seen as a temporary fix
Hydroflurocarbons (HFCs)
safe CFC alternative; contain carbon, fluorine, and hydrogen; don’t directly affect stratospheric ozone; doesn’t deplete O3 but does have other adverse enviro’l effects (may contribute to global warming)
Hydrocarbons
safe CFC alternative; butane or propane; ozone safe w/o chlorine but are flammable & poisonous
Clean Air Act Ammendments
require disposal of old refrigerators & air-conditioners; require older units to be modified to use newer coolants
Global Warming
steady increase in avg temp of Earth’s surface that may be caused by man-made greenhouse gas emissions; been observed since 1980s; debated over temp increase is natr’l or accelerated by human activity
Climate Change
any change in the state of climate that persists for many yrs; natr’l process; measured over at least 30 yrs
Greenhouse gases
soak up infrared radiation and trap heat in the atmosphere; widely associated with global warming
Natural Greenhouse Effect
essential to keep Earth’s climate warm and inhabitable
Carbon dioxide
most prominent greenhouse gas; sources: burning fossil fuels, fires, decomposition, deforestation; spends avg of 50-100 yrs in atmosphere
Carbon Tetrachloride (CCl4)
primarily used in production of cleaning fluids, esp in manufacture of military airplanes & spacecrafts; avg time in atmosphere: 50 yr
Halons
used in fire suppression and dry-cleaning supplies; found naturally in smoke plume of burning biomass & phytoplankton; relative warming effects are 6,000x CO2
Methane (CH4)
avg time in atmosphere: 15 yrs; warming facto of 25 x CO2; sources: cattle, coal, natr’l gas leaks
Nitrous Oxide (N2O)
avg time in atmosphere: 115 ys; relative warming potential: 300x CO2; source: burning of fossil fuels, livestock waste, fertilizers, & plastic manufacturing
Sulfur Hexafluoride (SF6)
used in heavy industry to insulate high-voltage equipment and to assist in manufacturing cable cooling systems; replaced carchinogenic PCBs; avg time in atmosphere: 3,200 yrs; 24,000 x CO2 relative warming potential (highest)
Water vapor
as temps increase, more water evaporates and causes add’l water vapor to ruse into atmos; natr’lly occurring
Carbonic Acid (H2CO3)
affects the pH of seawater; formed by an increase of CO2 in the atmosphere; as CO2 increases in atmosphere, oceans absorb CO2 and the CO2 and water mix to form ____
El Nino
produce increased warming of the Pacific Ocean every 2-7 yrs; frequency has increased over recent years; may be linked to global warming but these cycles are hard to predict
La Nina
produce cooling of surface waters near the equatorial region of the Pacific Ocean evry 2-7 yrs; has been more rare in recent years
Carbon Sinks
areas such as plants and oceans that absorb CO2 from the atmosphere
Kyoto Protocol (1997)
goal is to stabilize greenhouse-gas concentrations in atmosphere at a level that would prevent climate change; signed by 187 nations that are committed to reduce CO2, CH4, N2O, & SH6; agreed to reduce GHG emissions by 5.2%; US has not signed
Biodiversity
variety of organisms found within a specific geographic area
Niche
a species’s role in a community
Factors That Make Ecosystems’ Biodiversity Decline (HIPPCO)
Habitat destruction, degradation & fragmentation; Invasive species; Population & resources use increases; Pollution; Climate change; Overexploitation
bycatch
sea animals (dolphins & seals for example) caught unintentionally as part of netting or long-lining techniques
Endangered Species
animals/plants so rare they are in danger of becoming extinct
Threatened Species
plants/animals projected to become endangered within the foreseeable future
Vulnerable Species
face a high risk of extinction in medium term