Short Term Changes To The Carbon Cycle

Question 1

Diurnal changes

Answer 1

Carbon flows during the day from the atmosphere to vegetation

Flux is reserved at night

Lower sunlight - reduces photosynthesis in vegetation on land and the phytoplankton in oceans - vegetation loses co2 to the atmosphere

Same occurs in phytoplanktons in the oceans

Question 2

Seasonal changes

Answer 2

Controlled by the intensity of solar radiation

UK solar radiation intensity peaks in mid June

Middle and High latitudes, day length temperature and photoperiod drive changes in NPP.

Seasonal variation in the tropics can mainly be due to water availability

Summer input in southern June is about 800 w/m2

In December the input falls to just over 150w/m2

Therefore, evaporation is highest in the summer
Month to month variations in NPP

Summer months in the northern hemisphere = net flow of co2 from the atmosphere to the biosphere as vegetation is in full foliage and photosynthesis is rapid. Atmospheric co2 levels fall by 2ppm

End of the summer - photosynthesis declines - natural decomposition releases co2 back into the atmosphere

During the growing season ecosystems such as the Boreal and temperate forests extract co2 from the atmosphere which has a global impact

Oceans - the phytoplankton are stimulated into photosynthetic activity by rising water temperatures, more intense sunlight and a lengthening photoperiod.

North Atlantic - explosion of microscopic oceanic plant life which starts in March and peaks in mid-summer

The resulting algal blooms are so extensive they are visible in space

Question 3

Remote sensing

Answer 3

NASA’s Orbiting Carbon Observatory - measuring the effectiveness of absorption of co2 in plants

NASA’s MODIS - measures NPP in oceans and on land