Since this reflection is late already and most of the modules have been covered previously.
Thus, I shall spend my part on carbon cycle together with Greenhouse effect.
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.
It is one of the most important cycles of the earth and allows for carbon to be recycled and reused throughout the biosphere and all of its organisms.
Carbon exists in the nonliving environment as:
—carbon dioxide (CO2) in the atmosphere and dissolved in water (forming HCO3−)
—carbonate rocks (limestone and coral = CaCO3)
—deposits of coal, petroleum, and natural gas derived from once-living things
—dead organic matter, e.g., humus in the soil
Carbon enters the biotic world through the action of autotrophs:
—primarily photoautotrophs, like plants and algae—use the energy of light to convert carbon dioxide to organic matter.
—to a small extent, chemoautotrophs—bacteria and archaea
Carbon returns to the atmosphere and water by
—respiration (as CO2)
—decay (producing CO2 if oxygen is present, methane (CH4) if it is not.)
Unfortunately, the extent of its importance is rarely stressed enough.
Without the proper functioning of the carbon cycle, every aspect of life could be changed dramatically.
Carbon dioxide is transparent to light but rather opaque to heat rays.
Therefore, CO2 in the atmosphere retards the radiation of heat from the earth back into space — the “greenhouse effect”.
Has the increase in carbon dioxide led to global warming?
Average temperatures do seem to have increased slightly (~0.6°C) in the last century.
—Careful monitoring of both ocean and land temperatures.
—Many glaciers and ice sheets are receding.
—Woody shrubs are now growing in areas of northern Alaska that 50 years ago were barren tundra.
—Many angiosperms in temperate climates are flowering earlier in the spring than they used to.
—Many species of birds and butterflies are moving north and breeding earlier in the spring.