green house
- Thread starter haigan123
- Start date
HI
The earth is surrounded by an atmosphere through which solar radiation is received. The atmosphere is not static but contains air, in constant motion, being heated, cooled and moved, water being added and removed along with smoke and dust. Only a tiny proportion of the sun's energy reaches earth and some of this is reflected back into space (from clouds etc.). When the radiant energy reaches the land surface, most of it is absorbed, being used to heat the earth, evaporate water and to power photosynthetic processes.
The earth also radiates energy but, because it is less hot than the sun, this is of a longer wavelength and is absorbed by the atmosphere. The Earths atmosphere, thus acts like the glass of a green house, hence the 'greenhouse effect'.
he greenhouse gases (dealt with in subject 3) are those that absorb the Earths radiation and thus contribute to the greenhouse effect, but water is also a major absorber of energy. Where there is an increase in the concentration of greenhouse gases (as with CO2 due to the burning of fossil fuels) this results in an enhanced greenhouse effect - which is of concern as it could lead to climate change (i.e. global warming).
Soil processes
The potential for soils to support agriculture and distribution of land use will be influenced by changes in soil water balance:
bullet
Increase in soil water deficits i.e. dry soils become drier, therefore increased need for irrigation but:
bullet
Could improve soil workability in wetter regions and diminish poaching and erosion risk
Crops
The effect of increased temperature and CO2 levels on arable crops will be broadly neutral:
bullet
The range of current crops will move northward
bullet
New crop varieties may need to be selected
bullet
Horticultural crops are more susceptible to changing conditions than arable crops
bullet
Field vegetables will be particularly affected by temperature changes
bullet
Phaselous bean, onion and sweetcorn are most likely to benefit commercially from higher temperatures
bullet
Water deficits will directly affect fruit and vegetable production
Grasslands and livestock
bullet
There is unlikely to be a significant change in suitability of livestock for UK systems
bullet
Pigs and poultry could be exposed to higher incidences of heat stress, thus influencing productivity
bullet
Increase in disease transmission by faster growth rates of pathogens in the environment and more efficient and abundant vectors (such as insects)
bullet
Consequences for food quality and storage
Weeds, pests and diseases:
Weeds evolve rapidly to overcome control measures, short lived weeds and those that spread vegetatively (creeping buttercup, couch etc) evolve at the greatest rate:
Rate of evolution will increase in hotter, drier conditions and in 'extreme years', could lead to some types of herbicide tolerance becoming more common
bullet
Possible increase in the range of many native pests, and species that at present are not economically important may become so
bullet
Surveillance and eradication processes for other significant pests, such as the Colarado beetle will become increasingly important
Regards
Ashwini
The earth is surrounded by an atmosphere through which solar radiation is received. The atmosphere is not static but contains air, in constant motion, being heated, cooled and moved, water being added and removed along with smoke and dust. Only a tiny proportion of the sun's energy reaches earth and some of this is reflected back into space (from clouds etc.). When the radiant energy reaches the land surface, most of it is absorbed, being used to heat the earth, evaporate water and to power photosynthetic processes.
The earth also radiates energy but, because it is less hot than the sun, this is of a longer wavelength and is absorbed by the atmosphere. The Earths atmosphere, thus acts like the glass of a green house, hence the 'greenhouse effect'.
he greenhouse gases (dealt with in subject 3) are those that absorb the Earths radiation and thus contribute to the greenhouse effect, but water is also a major absorber of energy. Where there is an increase in the concentration of greenhouse gases (as with CO2 due to the burning of fossil fuels) this results in an enhanced greenhouse effect - which is of concern as it could lead to climate change (i.e. global warming).
Soil processes
The potential for soils to support agriculture and distribution of land use will be influenced by changes in soil water balance:
bullet
Increase in soil water deficits i.e. dry soils become drier, therefore increased need for irrigation but:
bullet
Could improve soil workability in wetter regions and diminish poaching and erosion risk
Crops
The effect of increased temperature and CO2 levels on arable crops will be broadly neutral:
bullet
The range of current crops will move northward
bullet
New crop varieties may need to be selected
bullet
Horticultural crops are more susceptible to changing conditions than arable crops
bullet
Field vegetables will be particularly affected by temperature changes
bullet
Phaselous bean, onion and sweetcorn are most likely to benefit commercially from higher temperatures
bullet
Water deficits will directly affect fruit and vegetable production
Grasslands and livestock
bullet
There is unlikely to be a significant change in suitability of livestock for UK systems
bullet
Pigs and poultry could be exposed to higher incidences of heat stress, thus influencing productivity
bullet
Increase in disease transmission by faster growth rates of pathogens in the environment and more efficient and abundant vectors (such as insects)
bullet
Consequences for food quality and storage
Weeds, pests and diseases:
Weeds evolve rapidly to overcome control measures, short lived weeds and those that spread vegetatively (creeping buttercup, couch etc) evolve at the greatest rate:
Rate of evolution will increase in hotter, drier conditions and in 'extreme years', could lead to some types of herbicide tolerance becoming more common
bullet
Possible increase in the range of many native pests, and species that at present are not economically important may become so
bullet
Surveillance and eradication processes for other significant pests, such as the Colarado beetle will become increasingly important
Regards
Ashwini