Carbon and water cycles threatened by human activity Flashcards
The burning of fossil fuels is not the only human activity that is disturbing the biological carbon and hydrological cycles. There are others related to the growing global demand for food, fuel and other resources, all of which are the outcome of continuing global population growth and economic development, what are they?
Deforestation
Grassland conversion
Urbanisation
What is deforrestation?
The clearance of forests both for their timber and for the land they occupy. In the latter case, the land is mainly cultivated to provide grazing for livestock or to produce cash crops.
However, it is not all bad news in that there is both reforestation and afforestation under way in temperate latitudes. This is helping to offset the loss of tropical rainforest services, but in the case of afforestation much is taking place on what was agricultural land.
What is grassland conversion?
Temperate and tropical grasslands have also become heavily exploited by agriculture. Both grassland types have suffered as a result of over exploitation. The simple act of ploughing leads to an immediate loss of both carbon dioxide and moisture, as well as a change in runoff characteristics.
What is urbanisation?
No land-use conversion is greater than that associated with urbanisation. Much space has already been taken over and many ecosystems completely destroyed by the insatiable demand for space needed to accommodate a rapidly rising urban population and their widening range of economic activities.
Of all forms of development, none is having a more disruptive impact on the carbon and water cycles than urbanisation. Towns and cities are focal points of both greenhouse gas emissions and intense water demand.
Three countries where there has been a net loss of forest areas
Brazil
Democratic Republic of the Congo
Australia
Three countries where there has been a net gain of forest areas
USA
India
Italy
What is ocean acidification?
Ocean acidification involves a decrease in the pH of the oceans caused by the uptake of carbon dioxide from the atmosphere.
What is a carbon sink?
A carbon sink is any natural environment (a forest, wetland or ocean) that is capable of absorbing more carbon dioxide from the atmosphere than it releases to the atmosphere.
The carbon sink function is the precursor to a particular environment becoming a carbon store.
What is ocean acidification the outcome of?
Ocean acidification is very much the outcome of climate change related to the burning of fossil fuels.
What is ocean acidification caused by?
The acidification is caused the oceans being important carbon sinks in the carbon cycle.
The health of the world’s forests as carbon stores is being challenged in what three ways and how are they related?
By deforestation
By the poleward shift of climatic belts
By increasing drought
The three are related in that the first and second are factors encouraging the third.
The diminishing health of the tropical rainforest (Amazon) means that it is what? (3)
Declining as a carbon store
Sequestering less carbon dioxide from the atmosphere, thereby exacerbating the greenhouse effect
Playing a diminished role in the hydrological cycle.
