Amazon rainforest: climate change

Question 1

• cattle ranching accounts for….% of deforestation
• impact on carbon and water cycles, thinking globally, nationally and locally
• explain how this is being managed by different organisations

Answer 1

• 80%
  (water) -fewer trees means a decrease in evapotranspiration, so the air becomes drier and vegetation dies out, limiting new growth (local) . this increases the risk of drought on a national level as surface waters runoff to river channels and water is not stored in the soil or aquifers as it is not given the time to infiltrate the soil (nationally). if deforestation levels are extensive, then reduced evapotranspiration means weather patterns can change on a continental level due to reduced moisture levels. reduced photosynthesis also means less carbon dioxide is absorbed, so global temperatures rise as the greenhouse effect is enhanced (global).
  (carbon) -without tree roots to hold the soil together, heavy rainfall washes away the nutrient rich humus layer of soil and transfers terrestrial carbon to the hydrosphere. the loss of the humus layer due to a lack of leaf litter means the soil cannot support new growth, so the land remains barren and less CO2 can be absorbed by the biosphere
• the Brazilian Forest Code is a law that forces landowners to keep 50-80% of their land as forest

Question 2

• hydroelectric dams proposed by the Brazilian government in ………………..have already displaced …………………people and flooded…………………..km2 of forest
• impact on water and carbon cycles, thinking local, national and global

Answer 2

• 2010, displacing 12,000 locals and flooding 400km2 of forest
• (water) the dams will alter the river basin’s structure and change the flow of water tot he hydrosphere, and also starve forest areas downstream of a constant water supply
• (carbon) new carbon stores int he form of lakes will be formed (local), however, the reduced river flow will mean less carbon is transferred into the hydrosphere, and the reduced growth int he forest due to reduced water supply means the transfer of carbon from atmosphere to biosphere through photosynthesis, and biosphere to hydrosphere and lithosphere through decomposition will cease (national).globally, this means a reduction in carbon emissions due to use of renewable energy sources however, the loss of vegetation means less carbon dioxide will be removed from the atmosphere, so the enhanced greenhouse effect may still lead to a rise in temperature

Question 3

an estimated ………species are going extinct every day

Answer 3

150-200 species

Question 4

since the 1850s, the average global temperature has risen by

Answer 4

0.8 degrees C

Question 5

in the amazon, the average temperature has risen by …………. every ten years since ……………..

Answer 5

risen by 0.26 degrees every ten years since 1975

Question 6

by 2050, temperatures in the Amazon will have risen by

Answer 6

2-3 degrees

Question 7

………….million hectares of forest are destroyed each year from 2000-10

Answer 7

3.6 million ha

Question 8

• amazonian topsoil contains ….-….kg of carbon in the top ………cm alone
• on the other hand, farmland contains only……kg of carbon per m3
• impact on carbon cycle

Answer 8

4-9kg of carbon in top 50cm alone
only 1kg per m3 in farmland

-this means the slow carbon cycle is disrupted and the concentration of atmospheric carbon increases