ELSS

• Amazon rainforest

  • High precipitation (2000mm/yr)
  • High temperatures allow the atmosphere to store large amounts of moisture (ie. absolute humidity is high)
  • Tropical temperatures (25-30°C)
  • Trade winds blow moisture from the Atlantic into the Amazon basin
  • Dense vegetation-tall, hardwood trees
  • High-intensity, convectional rainfall interception by forest trees is high (around 10 percent of precipitation)
  • Intercepted rainfall accounts for 20-25 per cent of all evaporation
  • Around a half of incoming rainfall is returned to the atmosphere by evapotranspiration. Most evaporation is from intercepted moisture from leaf surfaces
  • Dense cloud cover to stabilise forest albedo
  • Lots of interception from canopy/trees and dense vegetation (around 10% of incoming rainfall is intercepted)
  • Very little seasonal variation in climate
  • Rapid nutrient cycling in rainforest soils-intense rainfall can lead to soil leaching/rapid surface run-off
  • Abundant fanfall and deep tropical soils lead to significant water storage in soils and aquifers
• Alaskan tundra

  • Low precipitation (less than 100 mm/yr) with most falling as snow
  • Low humidity and small atmospheric stores of moisture
  • Temperatures can reach -40°C
  • Limited transpiration because of the sparseness of the vegetation cover and the short growing season of only about three months
  • High albedo- lots of sunlight reflected
  • Low rates of evaporation. Much of the Sun's energy in summer is expended melting snow so that ground temperatures remain low and inhibit convection
  • Also,surface and soil water are frozen for most of the year
  • Sun can remain below the horizon for weeks during the winter, but there are long daylight hours in the summer
  • Very little seasonal variation in climate
  • Melting ice/snow in summer creates vast lakes and ponds
  • Permafrost creates a barrier to percolation-limited groundwater stores
  • Accumulation of snow and river/lake ice during the winter months. Then melting of snow, river and lake ice, and the uppermost active layer of the permafrost in spring and early summer, results in a sharp increase in river flow
• Carbon cycle in Amazon rainforest


  1. Rapid decomposition

  2. 400bn trees store 68bn tonnes of carbon

  3. 60% of rainforest carbon is stored in above ground biomass

  4. Rest is stored below ground as roots and soil organic matter

  5. Lots of respiration due to high biodiversity

  6. Leached and acidic soils contain limited amounts of carbon and nutrients

  7. High rates of carbon fixation and rapid carbon exchanges
• Permafrost


  A vast carbon sink as slow decomposition (limited organic matter, desert conditions)
• Permafrost


  • Snow cover insulates microorganisms, allowing for some decomposition
• Carbon cycle in Alaskan tundra during growing season


  Tundra plants input carbon-rich litter to the soil
• Alaskan tundra

  • Limited photosynthesis and respiration due to lack of flora/fauna
  • Short growing season where plants flower and fruit in a few weeks
• Amazon Rainforest

  • Temperature around 25-30 degrees
  • Annual rainfall exceeds 2000mm and is convectional
  • NPP is 2500 g/m²/yr
  • Tall, evergreen hardwood trees
  • Extensive lowlands with gentle relief for most of the drainage basin, steep relief in the Andes to the west, extensive floodplains at the Pantanal
  • Sandstone and limestone found between the ancient shields
• Deforestation in Amazonia averaged around 17.500 km/year between 1970 and 2013
• Since 1970 almost one-fifth of the primary forest has been destroyed or degraded
• Converting rainforest to grassland


  Increases run-off by a factor of 27, and half of all rain falling on grassland goes directly into rivers
• Rainforest trees


  • Crucial part of the water cycle extracting moisture from the soil, intercepting rainfall and releasing it to the atmosphere through transpiration, as well as stabilising forest albedo and ground temperatures
  • This cycle sustains high atmosphere humidity which is responsible for cloud formation and heavy conventional rainfall
• Croplands and pastures contain only a small amount of carbon compared to forest trees
• Soils, depleted of carbon and exposed to strong, sunlight, support fewer decomposer organisms, thus reducing the flow of carbon from the soil to the atmosphere
• Modern strategies to manage the Amazon rainforest sustainably


  • Protection through legislation of large expanses of primary forest so far unaffected by commercial developments
  • Projects to reforest areas degraded or destroyed by subsistence farming, cattle ranching, logging and mining
  • Improving agricultural techniques to make permanent cultivation possible
• Increase in river discharge in spring


  1. Snow being accumulated over winter

  2. Lake ice melt

  3. Active layer of permafrost also melts
• Discharge in winter of Yukon River: 340 cumecs
• Discharge in summer of Yukon River: 24600 cumecs
• Permeability


  Low due to extensive permafrost and impermeable Precambrian igneous and metamorphic rocks
• There are over 3 million lakes in the tundra
• Wetlands in Alaskan tundra are in the Yukon River valley, in river deltas, along the coast especially of Bering Sea
• Reasons for extensive wetlands, ponds, lakes on the tundra during summer


  • Permafrost impeding drainage
  • Increasing surface water storage
  • Ancient rock surface which underlies the tundra weathered and eroded over hundreds of millions of years to a gently undulating plain
  • Flat relief reduces speed of overland flow & through flow within active layer
  • Chaotic glacial deposits impede drainage causing waterlogging in summer
• The North Slope of Alaska, between the Brooks Range in the south and the Arctic Ocean in the north, is a vast wilderness of Arctic tundra. Oil and gas were discovered here at Prudhoe Bay in 1968.
• Oil and gas exploitation on Alaska's North Slope


  Significant impacts on the permafrost and on local water and carbon cycles
• Permafrost, the major carbon store in the tundra, is highly sensitive to changes in the thermal balance
• Causes of permafrost melting


  • Construction and operation of oil and gas installations, settlements and infrastructure diffusing heat directly to the environment
  • Dust deposition along roadsides creating darkened snow surfaces, thus increasing absorption of sunlight
  • Removal of the vegetation cover which insulates the permafrost
• Permafrost melting releases CO2 and methane (CH4)
• On the North Slope, estimated CO2 losses from the permafrost vary from 7 to 40 million/tonnes/year, while CH4 losses range from 24,000 to 114,000 tonnes/ year
• Gas flaring and oil spillages also input CO, to the atmosphere
• Destruction or degrading of tundra vegetation


  Reduces photosynthesis and the uptake of CO2 from the atmosphere
• Thawing of soil increases

  Increases microbial activity, decomposition and emissions of CO2
• CO2 emissions from North Slope permafrost are estimated to have increased by 73 per cent since 1975
• The slow-growing nature of tundra vegetation means that regeneration and recovery from damage takes decades
• Melting of the permafrost and snow cover


  Wetlands, ponds and lakes have become more extensive, increasing evaporation, Increases run-off and river discharge, making flooding more likely
• Strip mining of aggregates (sand and gravel) for construction creates artificial lakes which disrupt drainage and also expose the permafrost to further melting
• Insulated ice and gravel pads


  1. Roads and other infrastructural features can be constructed on insulating ice or gravel pads, thus protecting the permafrost from melting

  2. The Spine Road at Prudhoe Bay lies on a 2 m deep pad
• Buildings and pipelines elevated on piles

  1. Constructing buildings, oil/gas pipelines and other infrastructure on piles allows cold air to circulate beneath these structures

  2. This provides insulation against heat-generating buildings pipework, etc. which would otherwise melt the permafrost
• Drilling laterally beyond drilling platforms

  1. New drilling techniques allow oil and gas to be accessed several kilometres from the drilling site

  2. Shell has developed the snake drill, which allows directional drilling across a wide area from a single drilling site

  3. With fewer sites needed for drilling rigs, the impact on vegetation and the permafrost due to construction is greatly reduced
• More powerful computers


  1. Can detect oil- and gas-bearing geological structures remotely

  2. Fewer exploration wells are needed thus reducing the impact on the environment

  3. About 10 percent of all supercomputers have been delivered to the oil industry

  4. Its two big computational tasks are sem data processing (to deduce underground geological structures), and reservoir modelling (to simulate the flows within a producing field, in order to optimise the amount of of that can be recovered)
• Refrigerated supportsare used


  1. Are used on the trans-Alaska Pipeline to stabilise the temperature of the permafrost

  2. Similar supports are widely used to conserve the permafrost beneath buildings and other infrastructure