Human Impact on the Environment

Question 1

draw the carbon cycle

Answer 1

ans on page 2 in booklet

Question 2

describe the effect of deforestation on the carbon cycle

Answer 2

it increases the carbon dioxide content in the atmosphere:
the removal of trees so less uptake of carbon dioxide from the atmosphere due to less photosynthesis

plants store carbon as biomass so burning the woody parts of trees releases carbon dioxide into the atmosphere

forested is replaced by crops which store less carbon dioxide and when crops die, decomposers undertake decay, releasing carbon dioxide

forest is often replaced with cattle that produce high levels of carbon dioxide and greenhouse gases such as methane

Question 3

describe the effect of climate change

Answer 3

human activities have resulted in global and regional climate patterns changing noticeably in the second half of the 20th century

the cause is thought to be the huge rise in atmospheric carbon dioxide levels and the rise in other greenhouse gases e.g. carbon dioxide, methane, nitrous oxides and water vapour

the two main reasons for the rise in carbon dioxide are combustion, the burning of fossil fuels releases carbon dioxide that was previously locked up and deforestation

Question 4

describe the effect of global warming

Answer 4

carbon dioxide is an important greenhouse gas, as it absorbs radiation from the Earth
if it accumulates in excess, it leads to global warming

this has resulted in increased frequency of extreme weather conditions, polar ice caps melting and an increased frequency of forest fires

consequently, species distribution may change; plants and animals may be driven to extinction if they cannot find a suitable new habitat fast enough, which reduces biodiversity

in some regions, there may be increased crop yields, but pest populations may also increase

Question 5

describe the effect of ocean warming

Answer 5

oceans can store a lot of heat so there is a time lag between warming of the atmosphere (which is linked to global atmosphere CO2 levels) and the warming of the ocean
CO2 is acidic in solution/CO2 dissolves in oceans making them more acidic

Question 6

give 5 consequences of global warming and climate change on aquatic habitats

Answer 6

decreased pH (acidification) of oceans - corals die, damages mollusc shells

increased rates of photosynthesis in aquatic habitats causing algal blooms

less oxygen dissolved in water at higher temps

fish migrate to cooler waters

reduced productivity on fish farming industry

Question 7

describe the effect of climate change with farming practices

Answer 7

agriculture is particularly vulnerable to the impacts of climate change and is affected through changes in temperature, and timing and quantity of rain
e.g. more flooding in the UK

extreme events, such as droughts and floods are likely to be more frequent due to climate change

as global warming increases, fresh water will be critical to sustain food production and feed the growing human population

Question 8

what are some possible changes in farming practices?

Answer 8

rotating crops to reduce pests and mineral depletion

salt-tolerant crops to overcome rising sea levels

feeding cows high-sugar grasses with less cellulose to reduce the release of the greenhouse gas methane

drought-resistant crops to tackle the low and fluctuating water supply

improving drainage to aerate water-logged and anaerobic soils
re-instating meadows

keeping the soil healthy by using minimal preparation of land for growing crops (tillage) and cover crops like clover to protect and improve soils between crops