Arctic Tundra

• 50-350mm precipitation due to low temperatures (nearly -40 sometimes), low transpiration due to low vegetation and short growing season
• Low evaporation because sun's energy mainly expended on melting snow but low ground temps
• Ground remains permanently frozen (only top metre thaws) and liquid water flows on surface
• Sun's rays spread over large area, ocean currents bring cold water, albedo high due to ice cover (reflection)
• Rock permeability low due to permafrost and Precambrian igneous and metamorphic rock
• This causes less infiltration and more water as surface run-off which is likely to freeze
• Drainage reduced, waterlogging increased in summer months due to flat plains from erosion
• Mineral composition of rocks has little influence on water cycle due to impermeability of permafrost
• Small stores of moisture in atmosphere from evaporation
• Temperature most influential factor on carbon cycle
• Slow decomposition and respiration and flow of CO2 to atmosphere due to low temperatures
• Less vegetation due to low temperatures and unavailability of liquid water for most the year
• This causes a small store of biomass (4-29 tonnes / ha)
• NPP less than 200 g / m2 / yr despite moss growing and flowering fast in the short summer
• Carbon mainly stored as partly decomposed plant remains in permafrost
• 5 x more carbon in soil than above ground
• Permafrost functioned as carbon sink, now it could be a carbon source due to global warming
• Increased leaf litter in summer meaning more carbon inputted into soils
• Photosynthesis low overall, but higher in the summer
• 9 billion tonnes of oil and gas under Arctic Ocean
• Oil and gas drilling causes localised melting due to removal of vegetation cover which insulates the permafrost
• There is increased run-off and river discharge so more flooding
• Permafrost melting releases 7-40 million tonnes of CO2 per year
• Gas flaring and oil spillages increase levels of CO2 in the atmosphere
• Less vegetation reduces photosynthesis and uptake of CO2 from atmosphere to biosphere
• Thawing of soil increases microbial activity, decomposition and CO2 emissions
• Spine Road at Prudhoe Bay lies on 2m deep pad which is insulating, protecting permafrost
• Shell has developed the 'Snake Drill' which allows oil and gas to be accessed several km from the drilling site
• Therefore less drilling sites are needed, so less impact on vegetation and permafrost from access roads and pipelines
• 10% of all supercomputers delivered to oil industry, so less exploration wells needed