3.b. The pathways and processes which control the cycling of water and carbon vary over time

Question 1

What device is used in order to monitor change

Answer 1

• satellites as they can measure atmospheric temp, sea surface temp and and surface temp
• these can be used on a temporal scale-day to day and epoch to epoch

Question 2

Durinal changes of climate, temperature, sunlight

Answer 2

• significant changes can occur within 24 hrs in water cycle- evaporation+transpiration lower at night due to temperature drop. Higher prec rate at night as temperature in clouds reach dew point
• high rates of carbon during daya to vegetation. The flux is reversed at night

Question 3

Seasonal changes of climate, temperature, sunlight- water cycle

Answer 3

-seasons controlled by variations in the intensity of solar radiation- UK solar radiation peaks mid June at 800W/m2. This has impact on evopotranspiration and precipitation rates- impact water cycle

Question 4

Seasonal changes of climate, temperature, sunlight- carbon cycle

Answer 4

• seasonal variations in carbon cycle shown in month to month variations in net primary productivity due to temp, photoperiod and water availability
• during summer months in norther hemisphere, there is a net global flow of CO2 from atmosphere to biosphere- levels fall to 2ppm. Flow reversed when photosynthesis ends
• seasonal fluctuations explained by concentration of continental land masses in northern hemisphere
• phytoplankton stimulated into photosynethetic activity by rising temp, intense sunlight and lengthening photoperiod. Explosion of microscopic ocean plant life results in algael blooms

Question 5

Long term changes key facrs

Answer 5

• over the last 1 million years, the global climate has been unstable, with large fluctuations in temepratures occurring at regular intervals
• in past 400,00 years there have been 4 major glacial cycles, with cold glacials followed by warmer interglacials. On much loner time scales, global temperatures have been even more extreme

Question 6

Impacts of long term climate change on water cycle

Answer 6

• during glacial periods water cycle undergoes changes- main is net transfer of water from ocean reservoir to storage in ice sheets, glaciers and permafrost
• sea level worldwide falls by 100-130m and ice sheets and glaciers expand
• ice sheet advance destroys forest and grassland
• water stored in the biosphere shrinks
• climate becomes drier and deserts+grasslands displace large areas of rainforrest
• lower evapotranspiration rates- reduce exchanges of water

Question 7

Impacts of glacials on carbon cycle

Answer 7

-reduction of CO2 in atmosphere- at times of glacial maxima C02 concentrations fall to
180ppm
-changes in oceanic circulation bring nutrients to surface- phytoplankton grow rapidly and fixes co2 in photosynetheis. When they die, the carbon is stored in the deep ocean
-the carbon pool in vegetation shrinks during glacial periods as ice sheets advance and occupy large areas of the continents. Deserts expand, tundra replaces temperate forests and grasslands
-less exchange of carbon between the soil and atmosphere due to ice coverage. Increase in coverage means less vegetation and reduction in carbon fixed by photosynthesis