The anthropogenic impact or the enhanced greenhouse effect
There are more than 8000 big coalfired powerplants in the world..
More than a billion cars, boats, aeroplanes, tractors, lawnmowers, charcoal grills and millions of factories and households, offices, transport of fuels - all these use the air as a wastebasket for emissions from the burning of fuels. Every hour, 24 hours a day, year round, mankind uses energy corresponding to 10 million barrels of oil. Most of this energy comes from coal, oil and gas; the fossil fuels.
- Some say the air is so vast that whatever the humans do, it will have no harmful effects outside a small area - and then it is gone with the wind.
We human beings are far too insignificant to be able to have an impact.
Compared to an eruption from a volcano, we are nothing.
- Others say that we have the effect of a permanent volcano, and in a human perspective, much of our emissions are irreversible.
We have already changed the chemistry of the atmosphere.
We are the first generation that really is able to have an impact at a global level, and the last generation to get away with it without paying a heavy price.
In other words - there is no free lunch, and somebody will always end up paying the bill.
- The greenhouse effect is natural and necessary for life on Earth.
The anthropogenic, enhanced greenhouse effect is due to the burning of fossil fuels and land use change.
The enhanced greenhouse effect is according to many scientists a serious threat to climate stability, and may lead to the extinction of many plant and animal species and may jeopardize human civilisation itself.
- There are two main categories of emission sources:
Stationary combustion in: Power plants, industry, oil installations, offices and households and
Mobile sources: Cars, trucks, aeroplanes, ships, dieselpowered trains.
Traffick situation, NewDelhii. Photo: Å. Bjørke
- The most closely studied radiatively active gas is CO2.
CO2 concentrations in the atmosphere have been measured at an altitude of about 4,000 meters on the peak of Mauna Loa mountain in Hawaii since 1958.
The measurements at this location, remote from local sources of pollution, have clearly shown that atmospheric concentrations of CO2 are increasing.
Combined with ice-core data the conclusion is that the mean concentration of approximately 280 parts per million by volume (ppmv) in 1750, rose to 316 parts per million by volume (ppmv) in 1958 and again rose to approximately 369 ppmv in 1998, and to 388 ppmv in 2010.
The annual variation is due to CO2 uptake by the photosynthesis process in growing plants . The uptake is highest in the northern hemisphere springtime.
The continuous increase depicted in the Keeling or Mauna Loa curve, even sensitive to annual photosynthesis variations, cannot be explained by anything except by human emissions. The same curve has been reproduced at a hundred different sites far from any cities all over the world.
Source: WMO Climate into the 21st Century. Cambridge University Press 2003
- According to the National Centre for Atmospheric Research (NCAR), there are three clear factors at work:
- Solar activity contributed to a warming trend in global average temperature from the1910's through to the 1930's
- As industrial activity increased following World War II, sun-blocking sulfates and other aerosol emissions helped lead to a slight global cooling from the 1940's to the 1970's
- Since 1980, the rise in greenhouse gas emissions from human activity has overwhelmed the aerosol effect to produce overall global warming.