- Human industrial activities are believed to be adding to the amount of "greenhouse gases" naturally present in the atmosphere. There are mounting proofs that following the industrial revolution of the 18th and 19th centuries, which commenced in Britain and expanded to several parts of the world, the amounts of carbon dioxide, methane and other greenhouse gases in the atmosphere has increased somewhat. Greenhouse Gases (ghg) released from human activities or natural sources and trapped in the atmosphere acting as blanket preventing the earth's heat from escaping into space, thereby increasing the earth's temperature, creating variability in the world climate (Climate Change).

To know more about ghgs, follow the link Greenhouse Gases. As a result of the increasing temperature, our earth warms up - a phenomenon referred to as Global Warming. Since the start of the industrial revolution of the 18th century, the temperature rise has been on the upward trend and it is believed that it will continue to rise. This lends further credibility to the scientific conclusion that humans are contributing to Global Warming. Global warming comes with a lot of consequences (see Evidences & Effects of Global Warming)

Based on scientific results and day-to-day physical evidences, global warming (caused by humans) is no longer in dispute. With the the verdict of the fourth assessment report on climate change prepared by the Intergovernmental Panel on Climate Change (IPCC), there is also very little contention that man contributes to the heating up of the Earth. However, the question that remains is: how much of the warming is caused by man?

Some of the human activities that lead to production of GHGs are:

Agriculture

During agricultural practices, methane gas (a GHG) is produced when bacteria decomposes organic matter. It has been estimated that close to a quarter of methane gas from human activities result from livestock and the decomposition of animal manure. Paddy rice farming, land use and wetland changes are also agricultural processes that contribute to the release of methane to the atmosphere.

Deforestation

With the growth of industrial activities, more and more trees are felled (e.g. in the wood industry, paper industry etc). These trees are felled without replanting new ones. This practice, over the centuries, has led to worldwide deforestation. Deforestation increases the amount of carbon dioxide in the atmosphere. this is explained as follows: During photosynthetic process, trees take in carbon dioxide from the atmosphere and release oxygen back to the atmosphere. With deforestation, the number of trees available to take in CO2 from the atmosphere has greatly reduced, leading to more available CO2 and increased greenhouse effect. Furthermore, when felled trees are burned to provide energy or when they decompose, carbon dioxide is also released to the atmosphere, further worsening the climate change - global warming phenomenon.

Fossil Fuels

Fossil fuels (coals, natural gas and oil) are widely used to power our modern day engines and automobiles. The burning of fossil fuels yields most of the energy used to produce electricity, heat houses, run automobiles and power factories. The burning of fossil fuels to obtain energy to drive these engines lead to production of tremendous amount of CO2 which is released to our environment and increases the concentration of CO2 in the atmosphere. It is believed that CO2 generated from the burning of fossil fuel accounts for about three-quarters of the total CO2 emissions from human activities.

Refrigeration/Fire Suppression/Manufacturing

Establishments and Industries used to use chlorofluorocarbons (CFCs) in refrigeration systems, and CFCs and halons in fire suppression systems and manufacturing processes. These substances are GHGs that are capable of adding to the phenomenon of Climate Change - Global warming.

Other Human Factors

Other human factors leading to release of GHGs (particularly methane) to the atmosphere include:

• pipeline losses;
• landfill emissions and
• septic systems that enhance and target the fermentation process.

Indicators of the Influence of Human Activities on Climate Change:

Measurements of the concentrations of CO2, CH4, NO2 and other GHGs in the atmosphere over time suggests that these concentrations have been on the increase since the beginning of the industrial revolution that began in the 18th century. A couple of the graphical data is presented on this page to illustrate that man's activities are possibly contributory to the heating up of our Earth.

Other Sources of Information:

• Causes of Climate change - Edugreen
• Intergovernmental Panel on Climate Change (IPCC)
• United Nations Framework Convention on Climate Change
• World Meteorological Organization (WMO)
• United Nations Environmental Programme (UNEP).