1	Global Change & Extinctions Most organisms have an effect on the world (eventually a difference could be detected if they were gone), but humans have had a growing effect for quite a while.
2	Readings P1162 – 1164 P1272 – 1277 p1252 - 1262
3	How have humans changed the world? Acquisition of fire (Homo erectus, 1 mya) Weapons that can kill at a distance Communication systems at a distance Transportation around world (boats, airplane) Industrial manufacturing (poisons, fixed nitrogen) Money as a measure of value Political and economic systems that allow accumulation/concentration of resources
4	FIRE Grasslands evolved before humans (silica in stems wore down the teeth of herbivores) But, grasses are an herbaceous plant that burns during the dormant season and that benefits from top killing of woody plants. Grasses and grasslands have benefited from humans use (and abuse of fire).
5	Weapons Weapons have had a dramatic effect on other species. Weapons allow humans to kill large animals, in many cases they changed humans from prey to predator. Bows and guns extended the distance through which the weapons were effective. Extinction of the Passenger Pigeon was result of weapons and economics.
6	Extinctions Since 1500, over 140 species of birds have become extinct. Passenger pigeon Carolina parakeet Around 60 species of mammals have become extinct. Human activity was associated with most recent extinctions.
7	Communication Systems Speech Written words (permanence) Telegraph Telephone Satellites (world wide communication)
8	Transportation Wheel Boats Automobile & trucks Trains Airplanes Spread of people and with them microbes, animals and plants that have had dramatic effects on world.
9	Industrial Processes Creation of tools that have altered the world. Tractor, plow, chain saw, etc. Creation of compounds that are new to natural world. DDT, PCB, nylon, etc. Electrical generation and distribution. Fixation of atmospheric nitrogen.
10	Money and Politics Money is a system of value that individuals substitute for biological value. Money and collective control allow the concentration of resources on projects involving many people. Research and culture advance through this concentration of resources.
11	Where it makes sense to live 1870 homesteading Water 1900 urban environment Rail transportation, can heat but not cool 1970 Roads, energy to both heat and cool
12	Energy Production & Consumption World oil use = 83 million barrels a day Oil is hydrocarbon probably of biological origin. World coal use = 4,686 million tonnes yr^-1 Burning of fossil fuels puts 6.3 gigatons of carbon into atmosphere as CO₂ What is the impact of burning carbon for energy?
13	Greenhouse Effect Energy from the sun = 1500 Watts per m² Some of that energy is absorbed by the atmosphere but much reaches surface of earth. Energy absorbed by molecules is often reradiated as heat (Infrared). Certain gases effectively absorb infrared radiation.
14	Glass models the greenhouse effect Visible light (and associated energy) goes thru glass quite well. Infrared light (longer wave lengths than red) does not go thru glass. Greenhouses are warm because energy of visible light is absorbed and reradiated as infrared which can not escape thru glass.
15	Greenhouse gases Gases that absorb part of the radiation reradiated from the earth surface are known as green house gases. Carbon dioxide (now 380 ppm) Nitrous oxide (N₂O) now 320 ppb (parts per billion) Methane (CH₄) now 1770 ppb Chlorofluorocarbon (Freon) 800 ppt (trillion)
16	Trends in greenhouse gases Carbon dioxide is going up, 1.7 ppm yr^-1 Burning of fossil fuel for energy Nitrous oxide is going up, 0.7 ppt yr^-1 Catalytic converter on automobiles Generation of electric power Agricultural nitrogen Methane is stable Chlorofluorocarbon is declining, -2 ppt yr^-1
17	Major effect of changes in atmosphere is warming of earth Warming changes not only temperature but also precipitation. Changes will not be the same everywhere, but will be spatially structured. As much water is tied up as ice in glaciers, increased warming is melting glaciers and causing a rise in sea level.
18	Vocabulary Atmosphere Fire Gigaton Greenhouse gas Non-native species Radiation ppm ppb ppt