Question

1. Describe the nature of the carbon cycle, the transfer of carbon within a biological community, and how humans have impacted this very important nutrient cycle.

2. Evaluate the role that humans have played in global environmental change, with reference to five specific examples of defined impacts.

Answer 1

1.Carbn cycle is the reuse of carbon atoms that travel from the environment to the organisms and back to the environment.This sequence is repeated.It maintains the balance of carbon dioxide in the ecosystem.The CO₂ released by organisms through respiration is absorbed by the plants for photosynthesis.Carbon is the key element in food,major Source of energy,regulates the earth' temperature and a key element for photosynthesis.Carbon plays a vital role in sustaining the life on earth.The transfer of carbon within a biological community involves:

In earth,carbon is stored in rocks,ocean,sediments,atmosphere and living₂g organisms in different forms.Carbon can exist freely as in case of diamond or combines with other atoms to form compounds.These acts as reservoirs or sinks through which carbon circulates.The carbon is released into atmosphere through respiration and combustion of fossil fuels.This carbon dioxide is absorbed by plants for photosynthesis to make carbohydrate.The carbon enters the food chain as carbohydrates through animals that feed on plants.Most of the carbon is released into atmosphere as carbon dioxide by respiration .When plants and animals die ,the carbon stored in their body is released into atmosphere as carbon dioxide through decomposition by decomposers.If decomposition doesn't occur,the carbon gets stored in fossil fuels and released by combustion.

Humans have a great influence in this nutrient cycle.Human activities increase the release the carbon dioxide to the environment and destroys the balance of ecosystem.Industrial activities like mining,petroleum refining,mineral production etc release carbon dioxide.Excess burning of fossil fuels ,pollution,exploitation of land,exhaust from automobiles etc release CO₂.Most of the carbon dioxide is absorbed by ocean.Excess absorption can lead to ocean acidification and harm the marine life.This imbalance can climate changes like unpredicted seasons,El-Nino ,global warming etc.

2.Humans have a vital role in global environmental changes.Their activities have lead to imbalance in the ecosystem.Human activities destroyed the rhythm of nature's balance.Overpopulation,pollution of natural resources,overuse of land ,deforestation ,destroying forest land to agriculture,mining,petrol and natural gas refining,quarries ,excess burning of fossil fuels,exhaust from automobiles,urbanization etc are some of the human activities that resulted in global environmental changes.These activities release excess carbon dioxide and other greenhouse gases which ultimately increase the global temperature resulting in various climatic changes.In fact we are ourselves destroying our habitat.Some of the impacts are:

• Global warming: It is one of the dangerous side effects due to human activities.The increased release of carbon dioxide and other greenhouse gases due to combustion of fossil fuels,burning of plastic,mining etc leads to increased green house effect.Green gases traps the outgoing solar radiation from the earth and keeps earth warm during night.But increased greenhouse gases can trap more solar radiation and increase the global temperature.This global warming can lead to the the melting of ice caps in polar region,which results in increase in sea level.Global warming can destroy the natural habitats of many rare species can lead to their extinction
• Ocean acidification: Most of the carbon dioxide released is absorbed by the oceans.Increase in the absorption of CO₂ leads to ocean acidification.THis can kill the marine life and destroy the natural ecosystem
• Land slides and soil erosion: Human activities like construction of buildings,mining ,quarrying,deforestation,misusing forest lands for agriculture etc. weakens the soil bond and leads to landslide and erosion.
• Pollution: The disposal of industrial waste,untreated sewage and chemicals into water bodies,dumping waste and radioactive material to the soil,release of automobile exhaust into air have deteriorated the quality of water,soil and air.This changes lead to destruction of natural inhabitants and resulted in several disorders.
• Climate change: All human activities lead to climate change.Burning of fossil fuels,automobile exhaust,mining,deforestation etc have shaken the balance of nature and leads to climatic changes such as unpredicted monsoons,EL-Nino,drought,flood etc.