3b. The pathways and processes which control the cycling of water and carbon vary over time
Diurnal changes
Seasonal changes
Long term changes
Importance of research and monitoring techniques
SSTs (Sea surface temperatures )
Radiometers measure the wave band of radiation emitted from the ocean surface
Changes in global SSTs and areas of upwelling and downwelling
Importance
Using GIS techniques these data can then be mapped and analysed to show areas of anomalies and trends, and regions of greatest change
Ground based measurements of environmental change at a global scale are impractical, monitoring relies heavily on satellite technology and remote sensing
Artic sea ice - Measures microwave energy radiated from Earths surface. Comparison of time series images to show changes
Atmospheric CO2 from NASA's Orbiting Carbon Observatory-2
Ice caps/glaciers - Using laser technology to show extent and volume of ice and changes
Water vapour - Measures cloud liquid water, total precipitable water
Water cycle
Carbon cycle
Water cycle
Carbon cycle
Lower temperatures at night reduce evaporation and transpiration
24 hour period changes
Convectional precipitation depends on direct heating of the ground surface by the sun, is a daytime phenomenon often in afternoon when temperatures reach a maximum
Significant in climatic regions in the tropics where the bulk of precipitation is from convectional storms
CO2 flows from the atmosphere to vegetation in the daytime
At night CO2 Plants --> atmopshere
No sunlight = no photosynthesis
Occurs with phytoplankton in the oceans
Evapotranspiration highest in the summer months and lowest in the winter
Month-month changes in NPP
In middle and high latitudes, day length and temperature drive seasonal changes in NPP
During Northern hemisphere summer net global flow of CO2 from the atmosphere to the biosphere causing atmospheric CO2 levels to fall by 2ppm
Earths climate has been highly unstable with large fluctuations in global temperatures occurring at regular intervals
End of summer more decomposition releasing CO2 back to the atmosphere
Phytoplankton are stimulated into photosynthetic activity by rising water temperatures, more intense sunlight and the lengthening photoperiod
Northern hemisphere increase in ocean plants from March to mid-summer
Lowest soil moisture levels late summer
April evapotranspiration levels 54mm
July evapotranspiration levels 96mm
Water cycle
In the past 400,000 years there have been 4 major glacial cycles with cold glacials followed by warmer inter-glacials
Carbon cycle
Reduction of CO2 in the atmosphere
Water cycle
Net transfer of water from the oceans reservoirs to storage in ice sheets, glaciers and permafrost
As ice sheets advance Equator-wards they destroy extensive tracts of forest and grassland. The area covered by vegetation and water stored in the biosphere shrinks
In the Tropics the climate becomes drier and deserts and grasslands displace large areas of rainforest
Lower rates of evaporation during glacial periods reduces the rate of water cycling
Lower ocean temperatures also make CO2 more soluble in surface waters
Changes in ocean circulation that bring nutrients to the surface and stimulate phytoplankton growth
Phytoplankton fix large amount of CO2 by photosynthesis before dying and sinking to the deep ocean where the carbon is stored
Carbon pool in vegetation shrinks as they are covered with ice
More land surface covered by ice, carbon stored in soils will no longer be exchanged with the atmosphere
Expanses of tundra beyond the ice limit sequester huge amounts of carbon in permafrost
Slowing of the carbon flux and smaller amounts of CO2 retuned to the atmosphere through decomposition
Less vegetation cover, fewer forests, lower temperatures and lower precipitation, NPP and total volume of carbon fixed in photosynthesis will decline