Overview of the main topics you will encounter in Unit 12.
The difficulty lies, not in the new ideas, but in escaping from the old ones, which ramify, for those brought up as most of us have been, into every corner of our minds. —John Maynard Keynes, economist, Preface to The General Theory of Employment, Interest and Money (1935)
Prediction is very difficult—especially about the future. — Attributed to physicist Niels Bohr
- Plants use carbon dioxide, water and the sun’s energy to grow more plant material, while releasing oxygen.
- Other life forms “burn” the plants with oxygen to get that energy.
- If buried without oxygen, the plants aren't burned, and heating them makes fossil fuels.
- Woody plants→peat (in sediment; Bear Meadows)→lignite (in sedimentary rock)→bituminous (in harder sedimentary rock, western PA) →anthracite (in metamorphic rock, eastern PA) (lignite, bituminous, and anthracite are all types of coal).
- Algae→natural gas from bacteria (Bear Meadows)→oil (with natural gas) (western PA)→ natural gas (eastern PA) (natural gas and oil float up and escape to be burned by bacteria, etc., unless trapped by geology).
Take It to the Limit
- Fossil fuels are NOT infinite:
- Nature really is efficient at recycling;
- Oil & coal companies are really skillful, and already found the easy stuff;
- Not a lot is set aside (oil beneath Arctic National Wildlife Refuge is estimated to equal only just over 2 years of US imports).
- World oil production peak likely in next decades:
- At vaguely recognizable prices and current demand, probably close to a century of oil and gas, a few centuries of coal;
- But demand rising rapidly, so less time;
- This includes the gas from "fracking".
You’re in the Greenhouse Now
- Some gases in the air let visible light through (sun) but partly block infrared (return from Earth);
- Makes planet warmer than otherwise, so we “glow” brighter, forcing energy past the gases to space;
- We are increasing these gases (esp. carbon dioxide) a lot, and they will stay up for centuries, millennia, or longer.
With High Confidence
- Our greenhouse gases will warm world, amplified by feedbacks such as melting of reflective ice increasing warming (maybe up around 15oF or more over centuries if we really burn fossil fuels, vs. 1oF or so thus far).
- Positive and negative impacts on us, but mostly negative for warming more than a few degrees:
- Sea-level rise from ice melt, expanding ocean;
- Summertime drying of grain belts;
- Not-nice tropical heat.
- We have to switch from fossil fuels; will we do so before or after we change the world?
- Reasonable estimates say switch needs few decades of serious research and 1% of economy:
- This is in line with other clean-up costs now;
- This is a lot of money.
- Not much scientific disagreement on these points;
- But much political, social, economic disagreement (which is completely expected, and in line with previous environmental issues).
Lions and Tigers and Bears?
- Biodiversity is valuable to us as a source of medicines and other useful things we can discover, and because more-diverse ecosystems produce more that we might use, and living types can serve as “canaries in the coal mine” to warn us of trouble; also, there are ethical issues of whether we have the right to extinguish other species.
- Early and modern humans have been hard on biodiversity and contributed to extinctions, and we may be heading for the next mass extinction.
- Just as smaller islands have fewer species because it is easier to eliminate a smaller population, isolating patches of wilderness in separate national parks will turn them into biological islands and cause loss of species in those parks.
- Climate change will make this worse, forcing migration when there may not be migration pathways.