ES 3 - Energy

Topic 3 – Energy

Current Global Conditions

-          Global Population

o   6 billion, increasing by 85 million every year

o   8 – 10 b by year 2050

o   What is the impact of 10b people on the planet’s resources?

-          Global Food Production

o   In the last 100 years global food production has exceeded demand even though world population has been growing rapidly. How do we achieve this?

o   Can humans maintain this pace?

o   Biotechnology and intensive farming may help produce more food in the future.  Can poor countries afford this?

-          Food Production

o   Food production has led to environmental degradation and degradation of agricultural land

o   Can we produce more food without degrading the environment?

o   Is food being distributed equitably around the world? The world produces excess food but 800 m people are undernourished; 20 m have food shortages due to bad weather and politics

-          Energy

o   How we obtain and use our energy is important in the future

o   Fossil fuels (oil, natural gas, coal) now provides 80% of energy needs of industrialised nations.

o   Supplies are diminishing; mining them is polluting the environment

o   Need clean technologies for the future: renewable energy resources (solar, wind, geothermal, biomass).  Also need conservation of energy

-          Global Warming

o   CO₂ emission from fossil fuel burning, forest cutting, agriculture, making cement, many human activities

o   CO₂ concentration increased 30% in last 200 years.  Mean global temp will increase by 1.5° and 6°C

o   Global climate change is already affecting many biological species; and severe weather events (floods and droughts)

o   Global warming will cause sea level rise and flooding of low-lying islands and coastal areas

o   90% humans to be blamed

-          Air Pollution

o   Toxic haze of ash, acids, aerosols, dust, photochemical products over continents (India)

o   3m people die each year due to air pollution

o   2 b metric tons of air pollutants released every year in the world

o   Air pollution is transboundary (transported by air currents over long distances) problem nowadays and not local (pollutants from south Europe pollute the Scandinavian countries and arctic ecosystem); China major problem nowadays

o   Mercury, polychlorinated biphenyls (PCB), DDT – all persistent chemicals- accumulate in snow and wildlife and native people in the Arctic

-          Habitat Destruction

o   Habitat destruction, overexploitation, pollution, introduction of exotic organisms are eliminating species at rates that caused extinction of dinosaurs

o   UN Environment Program says 800 species have disappeared over the last century and 10,000 species now threatened (Half of all primates and fish;10% of all plant species; top predators – big cats).

o   More than 75% of global fisheries are overfished

o   Forests are being cleared very rapidly in Brazil, Asia

Energy & Matter

-          Living systems are maintained by processes that capture energy from external sources and use it to carry out essential functions. Materials are used and recycled in these processes

-          Much of ecology is about understanding how energy and matter move through ecosystems

Food Chain, Food Webs & Trophic Levels

-          Photosynthesis provides all the nrgy for nearly all ecosystems

-          One of the major properties of ecosystems is productivity: the amount of biomass (biological material) produced in a given area during a given period of time

-          Primary producers photosynthesize while consumers get their nutrients by eating other things

-          Net productivity is the amount of primary production that accumulates in a system

Biotic component of Ecosystems

-          Producers = Autotrophs

o   Photoautotrophs

o   Chemoautotrophs

-          Producers are autotrophic photosynthetic organisms.

-          In terrestrial ecosystems, producers are predominantly green plants.

-          In freshwater and marine ecosystems, dominant producers are algae. 

1° and 2° productivity

-          Net primary productivity (NPP): the rate at which energy is stored in the body of producers by photosynthetic activity.
Gross primary productivity (GPP): the total production of organic matter (photosynthate) including the energy used for cellular respiration (R).

-          GPP = NPP + R

Biotic Components of Ecosystem

-          Consumers are heterotrophic organisms that eat preformed food.

-          Herbivores feed directly on green plants; are primary consumers.

-          Carnivores feed on other animals and are secondary or tertiary consumers.

-          Omnivores feed on both plants and animals; for example, humans eat both leafy vegetables and beef.

-          Decomposers are organisms of decay.

o   Mostly are bacteria and fungi.

o   Break down detritus, nonliving organic matter, into inorganic matter.

o   Small soil organisms are critical in helping bacteria and fungi shred leaf litter and form rich soil.

First Law of Thermodynamics

-          Energy can be changed from one form to another, but it cannot be created or destroyed

Energy Flow

-          It takes 100kg of clover to make 10kg of rabbit and 10kg of rabbit to make 1kg fox which means only 10% (less in most systems) of the energy at each stage is transferred to the next. This process is not that efficient.

Biomass pyramid

-          Shows that the amount of biomass decreases as you go up the trophic level of the food chain.

-          Nutrients and energy become less available to successive consumers

Carbon Cycle

-          Boxes in the figure refer to pools of carbon, and arrows refer to the movement, or fluxes, of carbon from one pool to another

-          Humans are altering the balances in carbon cycle