24 Sept 07, Monday Beginning of material for EXAM 2
Life in the Biosphere
Ecology is the study of how organisms interact with their environment
Rules of Ecology:
1. Energy flows through ecosystems in one direction and is lost as heat
Discussion: sunlight produces a spectrum of light which reaches the ground and
is used by terrestrial and aquatic plants for photosynthesis, vegetation is
consumed by animals, animals die, and soon everything becomes mushrooms
sun ----- uv, CO2 ---- plants ---- animals ---- decomposed
Note: when you change the form of energy, some energy loss occurs as heat
2. Energy and the earth’s ecosystems
As the sun’s energy hits Earth’s atmosphere, some of it is reflected and much of
the energy reaches the Earth’s surface and serves to heat the planet.
Cooling of the atmosphere
occurs due to: clouds, ice,
suspended particle matter (SPM) all reflect
heat and energy out into space
Heating of the atmosphere 1) CO2 2) perflochlocarbones
occurs due to: 3) Methane 4) water vapor
5) Clouds 6) hydroflurocarbons
7) Sulphur hexafluoride
All trap heat and radiate heat back to the surface
CO2 (carbon dioxide) is the most important greenhouse gas due to amount that
Which is prevailing? Cooling or heating?
Is global warming occurring? Yes, the planet is warming up.
Modeling of climate (temperature) change is done with natural factors,
anthropogenic factors, and a combination of the two. Both types of factors are
called forcing factors and the combination gives the best “fit” graphs of what we
see happening to the climate.
CO2 data and projections:
Carbon dioxide is the most important greenhouse gas. Models of the past and
present show the best scenario for the next 100 years is 550 ppm, 35% higher
than they are now. Temperature models show the same problems through time.
Methane is worst than CO2 for “trapping” heat, but we less methane than CO2 in
the atmosphere. This situation could change, as glaciers melt and release
Temperature Data and Projections:
Average temperature increase of 4.5 C (8.1 F) degrees
Effects of Global Warming
1. CO2 levels will increase and with this increase hurricanes will be fewer,
but greater intensity
2. By 2050 if usage of energy and production of greenhouse gases remains
the same – we will see deforestation in S. America and Africa, decrease crop
production in Africa, intensification of storms in the Gulf of Mexico, and
increasing disease in Siberia and Africa due to increase in insect populations and
movement of insects, water conflicts around the world
3. Artic Ice mass is decreasing, but rise in sea level is due mainly to the
expansion of water due to higher temperatures. Ice masses were created at a
time when methane was more abundant, it is now trapped in the ice, if the ice
masses melt this methane will be released.
World Response to Climate Change
In 1992 the UN Framework Convention for Climate Change was convened
and attended by virtually all countries
Kyoto Accord in 1997 to reduce green house gas emissions, CO2 levels
for each country assigned (7% in U.S.), penalties for not reaching these levels,
the Accord was not ratified by the Congress Note: the US and Australia only
two countries not to sign or ratify
The US did not ratify due to economic impact on the country and the fact
China and India were exempted from limits
The US and Canada are the top producers of CO2.
Need to cut current CO2 emission by 50-80% to stabilize atmosphere,
International Energy Agency (IEA) estimates 50% increase from 1990-2100.
-desertification will increase in some areas
-wetter in other areas, due to change in wind and weather patterns
-armed conflict over food could be in our future
Unanswered questions - How to “fix” the problem? Could we . . . . .
1. Fertilize the ocean - grow algae to uptake the CO2 from the
atmosphere, very expensive
Example: tried off Tasmania, added 9,000 + tons FeSO4
2. Clouds? With warming there will be more water vapor which will in
turn produce more clouds. Will they be reflective or trapping?
The answer is unknown due to lack of data.
3. Ice caps and solar radiation: Ice caps as they melt, ice is reflective
but water is trapping- the CO2 question becomes a process that
builds on itself
4. Forest loss? Forests are the next great area of CO2 fixing after the
ocean, old growth areas are fixing little CO2 due to little growth
occurring, new growth better at fixing.
Note: 1) Energy flows through the ecosystem with heat loss
2) Nutrients are recycled in the ecosystem
Nutrients - any element or compound needed for growth
Macronutrients O, C, N, H, P A nutrient needed in large
(oxygen, carbon, nitrogen, hydrogen, phosphorus)
Micronutrients Zn, Cu, Mg, Fe, I A nutrient needed in small
(zinc, copper, magnesium, iron, iodine)
Micronutrients can be toxic in larger quantities. Nutrients deficiencies in animals
humans are often difficult to detect, but can cause immune response
deficiencies, skin changes, loss of visual acuity,
reduced hemoglobin production.
Nutrients recycle in the ecosystem.
Nutrients are found in a fixed amount, but some are not in a useable form, for
Ammonia nitrite nitrate
N2 -----------------NH3, NH4+------------------ NO2 ------------------ NO3
N fixation Nitrification Nitrification nitrate to
Bacteria fix N in roots of plants, legumes
Nutrients are continuously recycled and converted to a useable from through a
variety of biological, geological, and chemical processes call Biogeochemical
Biogeochemical cycles Nutrient recycling systems
Discussion: Carbon cycle is the “simplest cycle”
Note: 213.8 Mtons of carbon is fixed