Need help with science home work about carbon dioxide?

Carbon dioxide (CO2) enters the atmosphere naturally mainly by decay of plants; it also comes from respiration of animals (exhaling), some from volcanic eruptions, evaporation from oceans, burning plants, and soil decay. Natural sources of CO2 are generally not a problem for the atmosphere as there is a natural cycle of carbon dioxide that has been in balance for billions of years until the only recent disruption by the industrial age. There are some exceptions to this prevalent natural balance such as major volcanic eruptions. The balance has been achieved by photosynthesis, the process in which plants consume CO2 and release oxygen (O2) while creating green plant matter, storing CO2 in leaves, branches, and roots. CO2 is also stored in oceans, both in phytoplankton and dissolved into the water. Thus, plants and oceans are the major sinks of CO2. The main anthropogenic (human made) source of CO2 in recent history is from the burning of fossil fuels. Increases in the rate of burning plants and deforestation release additional CO2, while deforestation further lowers the rate of photosynthesis by the plants that once consumed CO2 to maintain balance. With more CO2 entering the atmosphere than leaving, CO2 increases and builds up in the atmosphere. A major problem with the increased proportions of CO2 is that CO2 is a greenhouse gas. Higher surface temperatures of the Earth have many effects, including increasing the rate at which glaciers melt, raising the sea level. Shorter, warmer winters have more immediate effects such as algae build up in lakes, and pests moving farther north, for example. In the longer term, some ocean currents could even be altered which could leave Europe in a perpetual state of winter (as has happened in the past).