Around the world, the majority of respected climate scientists agree that the main cause of global warming is the human-influenced “greenhouse effect”. This is essentially a warming of the Earth because the atmosphere is trapping heat that radiates from the Earth outward to space.
There are certain gases in the atmosphere that block heat from radiating away from the Earth. Some gases are semi-permanent and don’t respond to changes in temperature – these are seen as “forcing” climate change. Other gases do respond to temperature change – they are “feedbacks.”
Water vapour is the most abundant of the greenhouse gases. It increases in volume, as the Earth warms up, and accounts for cloud formations and precipitation – a very important “feedback”.
Carbon Dioxide is another important component in the atmosphere, and is released naturally by various means, but also through human actions, one of which is the burning of fossil fuels.
Scientists have determined that humans have increased Carbon Dioxide levels in the atmosphere very substantially since the Industrial Revolution – an example of “forcing” climate change.
Methane is another gas that’s produced naturally (and through human action). Landfill waste and agriculture contribute to methane gas, while domestic livestock contribute through manure.
When compared, methane gas is much more active as a greenhouse gas than carbon dioxide. But at the same time, atmospheric concentrations are less abundant than carbon dioxide.
Nitrous Oxide is one of the more powerful greenhouse gases in the atmosphere. It’s a bi-product of soil cultivation, especially with commercial fertilizers, and when fossil fuels are burned.
Chlorofluorocarbons (also referred to as CFCs) are industrial compounds that are very regulated today because they are known to destroy the ozone layer. CFCs are also greenhouse gases.
Planets that have little greenhouse effect – like Mars – have a thin atmosphere, comprised mostly of carbon dioxide. With very little methane or water vapour, the greenhouse effect is weak.
Planets like Venus have a “runaway” greenhouse effect. Venus has 300 times the carbon dioxide as the Earth’s atmosphere – it makes for a surface temperature that will easily melt metal.
Human activities have contributed negatively to the “greenhouse effect”. Burning fossil fuels like oil and coal has significantly increased concentrations of carbon dioxide. As for agriculture and industry, these have contributed to a lesser degree to concentrations of greenhouse gases.
Beyond the causes of global warming, the after-effects are already evident. World temperatures are becoming warmer. Warm weather leads to more evaporation and more precipitation. Overall, some regions will become wetter and other regions will become dryer (even in extreme).
The more intense the “greenhouse effect”, the more prone oceans are to warm and glacial ice to melt. Ocean water also expands when it warms, which contributes to rising sea levels. In general, higher temperatures and changing climate change where crops will grow and thrive the best.
The United Nations has concluded that in all probability (90%) human activities have resulted in human-produced greenhouse gases (carbon dioxide, methane, nitrous oxide). These are the main contributors to increases in the Earth’s temperatures during the last 60 years.