1. Environmental science: a study of the processes that occur in and on the outer skin of the earth, largely fuelled by solar energy; interactions between the four spheres; "person" as a geological agent.
2. A minicourse in earth science: ocean floor spreading, rocks, sediments, plate tectonics, oceans, water cycle, atmospheric structure and composition.
3. The biosphere: subdivisions in 3 domains: autotrophs-heterotrophs; unicellular-multicellular; chemo-autotroph versus photosynthetic; prokaryote versus eukaryote (or the "If it has hair it is an animal" lectures); vent faunas in the deep sea.
4. Environmental pressures from personkind: I = P * T depend on per capita consumption patterns (which vary with culture, prices, public policies, incentives, etc) and world population size. Sustainable development versus current pattern; environmental costs externalized in products; energy usage is a strong factor in development and pollution.
5. Population growth: exponential growth, doubling times, sigmoidal growth curves, carrying capacity; R and K type populations; Malthus versus Cornucopians. Population growth in various parts of the world (values of r), relations to social systems (e.g., social security system), incentives for small families, position of women in society, use of contraceptives around the world.
6. Energy demand: relations between GNP and energy demand; influence of demographics; units of energy usage (quads); patterns of energy usage; energy conversions and efficiency (Carnot engine); energy demand growth scenarios.
7. Energy reserves and resources: fossil fuels-abundances and distribution; exponential expiration times. Origin of oil and gas; unconventional fossil fuel resources.
8. Nuclear energy: principles, types of reactors,
expected life-times, health and safety concerns; radio-active waste issues.
I hope that you all have enjoyed the first couple of weeks in EES 199. I did enjoy our joint exploration of the natural environment and the peoples living in it. I provide a short summary below, which will help you with your readings (Ch. 1-6) for the mid term.
We started with an overview of planet earth within the context of the Universe and solar system, origin of the elements that make up the world, the concept of a planet at the ‘right’ distance from the sun to have liquid water and what is all involved in that – interactions between the four spheres to keep the earth “habitable”. We discussed the inverse square Law (energy drops with distance R as 1/R2 because of the “radial pattern” of space) and made a note that the greenhouse effect is and always has been important. We then spoke about the origin of the main features of the earth and scanned over some of the dramatic environmental changes that the earth went through over its 4.5 billion year history. I did this to emphasize that change has always been a feature of the earth because it is a living planet (endosphere – energy from the inside fuelling plate tectonics, volcanism etc) and exosphere – the outer shell with processes fueled by solar energy. We touched upon the O2 free atmosphere in the early days, the onset of life after the cessation of the great bombardment with meteorites and the gradual build up of O2 (an early dramatic global environmental change as a result of “life’s activities”), followed by the concept of snowball earth (plants sucked all the CO2 from the atmosphere, no greenhouse, cold) and the recovery from it. Then we discussed shortly the nature of the fossil record with evidence for 3 mega extinctions and several smaller ones. We argued that the extinctions could be driven by external factors (be it from outside the earth – meteorites-, or from inside the earth – volcanic catastrophes-) or driven by events and developments in the biosphere itself (e.g., super high O2 in atmosphere because of intense photosynthetic productivity 300 million years ago – remember those dragonflies with wingspan of several m!). These considerations brought us to the modern world and its variety of natural and human environments, and we ended our review with the observation that people may be the first biological species that have the capability to make decisions about its own environment based on an interpretation of the past and projections for the future.
Our discussions of the environments of the modern world covered land and oceans, with an intro to primary productivity (photosynthesis and chemosynthesis) that form the base for all higher trophic levels. Jennifer discussed the structure of populations, communities and ecosystems and the sequence of community maturation (pioneer to climax communities) We looked shortly at an environment where chemosynthesis forms the basis of a whole ecosystem (hot spouter vents in the deep ocean) and then focused on the terrestrial biosphere and its biomes. We looked at the limiting factors for photosynthesis and discussed the two main nutrient cycles (P-rock bound, N- bacteria bound) and also discussed the human impacts on these nutrient cycles. We touched upon the subtle links between species and communities (Dodo and trees on Mauritius, see e.g., http://www.bagheera.com/inthewild/ext_dodobird.htm) and how intricate connections exist in the cycling of energy and elements.
We subsequently investigated the differences between nutrient cycling in the oceans and on land and dependencies between the two realms.
In a separate set of two lectures, we looked at the more general rule that phrases human impact on the environment I = P * T, where I is the human environmental impact, P is the population size, and T is the technology factor or the per capita impact. Usually we apply this relationship in local environments, but more and more we have to consider the cumulative effect of our behavior on the whole planet. We then investigated the details of population growth and came up with exponential growth as the common form (r is the intrinsic growth rate = birth rate minus death rate), which would lead to Malthusian scenarios. Then we looked into the gradual adaptation of r to the size of the population and derived the nature of the logistic population growth curve and the associated concept of the carrying capacity, K. We emphasized that we cannot easily predict the K value for humans (because we are an unpredictable lot in some senses), although much of the demographic research community does just that. In our own example (prob 1) we calculated for a given set of conditions the simple exponential growth, the logistic growth for an assumed adaptive scenario (Kb and Kd factors) and then we looked into the impact that a 1% death rate as a result of a ‘terrible disease’ would have. At the same time we learned the basics of Excel to calculate and visualize (plot) things, an important diagnostic tool in many respects.
In the last few lectures we looked at the nature and depletion of resources with the fundamental difference between mass resources (dispersal, can be recovered through energy input) and energy (2e law of thermodynamics – energy flows from high to low T and diffuse energy forms can not be recovered). We then looked at resources from the ethical point of view (intrinsic versus extrinsic values, the 5 e’s) and the modes of managing resources (preservation, conservation, restoration).
The next few lectures dealt with energy as a resource, origin and nature of fossil fuel resources and their extimated magnitudes.