Biological Consequences of Global Warming, Greenhouse-effect-t2 , image,…
Biological Consequences of Global Warming
The Greenhouse Effect
over the last hundred years human activities have resulted in rising concentrations of all the greenhouse gases. This has led to an increased or "enhanced" greenhouse effect and this in turn seems to have led to an increase in average global temperature.
that the greenhouse effect is a natural, essential process. Without it, the average temperature on earth would be about -17 degrees celsius and life would be impossible.
How it is caused.
Shortwave radiation from the sun reaches Earth's atmosphere
Some is reflected
But most gets through
Earth absorbs the radiation.
Earth's surface warms up and emits long wave radiation - i.e. it re-radiates energy.
Some of this re-radiated longwave radiation is trapped by CO2 , CFCs, CH4 , N2 O and water vapour - "The greenhouse gases"
Some longwave radiation escapes.
Biological and Ecological Consequences of Increasing Temperature
It is expected that greater warming will occur at the poles than at the equator and this will affect atmospheric circulation patterns which are dependent on the temperature differences between these two areas. Similarly, regional rainfall patterns may drastically change which in turn will affect the pattern of world food production, with obvious economic and political consequences.
Sea-levels will rise as a consequence of melting glaciers and thermal expansion of water. Consequences include flooding, salinisation of soils and coastal erosion. No one is sure how much the sea-level around Britain will rise - the most commonly quoted estimated rise by 2050 is 0.3 to 0.6 metres. The southeast, which is already sinking relative to the sea, would be the most seriously affected.
since pre-industrial times (around 1750), carbon dioxide concentrations have increased by just over one third from 280 parts per million (ppm) to 380 ppm today, predominantly as a result of burning fossil fuels, deforestation, and other changes in land-use. This has been accompanied by rising concentrations of other greenhouse gases, particularly methane and nitrous oxide.
Over the past 30 years, global temperatures have risen rapidly and continuously at around 0.2°C per decade. All of the ten warmest years on record have occurred since 1990.
Rising carbon dioxide concentrations in the atmosphere will stimulate photosynthesis and decrease water requirements by reduction in stomatal pore size. But, as a result of increased pests, increased water stress and critical temperatures being exceeded more often, overall cereal production is expected to decrease.(Fig
Warming is very likely to intensify the water cycle, reinforcing existing patterns of water scarcity and abundance and increasing the risk of droughts and floods.
Worldwide however, the trend is in the wrong direction, with one new car joining the roads every second. In Britain, road transport is responsible for 18% of carbon dioxide emissions,45% of nitrous oxide emissions and 30% of all hydrocarbon emissions.
What can be done
Strategies to reduce the emissions or levels of the greenhouse gases have mainly targeted carbon dioxide.
Reducing the consumption of fossil fuels by increasing the fuel efficiency of buildings and vehicles. Improvements to the latter would also reduce N2 O emissions.
Switching fuel from coal to oil and gas which release less carbon dioxide upon consumption.
Switching from fossil fuels to renewable energy sources such as solar, geothermal, wind, wave, tidal and hydro-electric.
Preventing destruction of the tropical rainforests, simultaneously removing a problem and providing a solution.
Because the other greenhouse gases absorb different infra- red wavelengths to carbon dioxide, reductions in this gas alone are unlikely to be sufficient. CFC emissions have already been reduced as a result of the Montreal Protocol in 1989 and subsequent amendments.