What Causes Climate Change?

Why is climate change important? Simple. Forecasting how climate will change over the next century, or understanding and forecasting what the coming winter might bring is of vital importance - both for our society and economy.

Humans are increasingly affecting the temperature and climate of the earth by farming livestock, cutting down rainforests, and burning fossil fuels. This adds tremendous amounts of greenhouse gases to those occurring naturally in the atmosphere, increasing global warming, and the greenhouse effect. The trend of global warming is attributed by the scientists to the human expansion of the greenhouse effect - warming, which arises when the heat radiating from the earth toward space is trapped by the atmosphere.

Some atmospheric gases block heat from escaping. The long-lived gases that remain in the atmosphere semi-permanently and don't respond chemically or physically to temperature changes are described as forcing climate change. Gases, for instance, which respond chemically or physically to temperature changes, are perceived as 'feedbacks.'

The human activities are changing the natural greenhouse on earth. In the last century, the burning of fossil fuels like oil and coal has amplified the concentration of atmospheric carbon dioxide. This takes place because the oil or coal-burning process fuses oxygen with carbon in the air to create carbon dioxide. To a lesser extent, the clearing of land for industry, agriculture, and other human activities have increased the concentration of greenhouse gases.

While it's difficult to predict the consequences of changing the natural atmospheric greenhouse, some key effects seem likely:

• A stronger greenhouse effect will increase sea level by partially melting glaciers and other ice and warming the oceans. The ocean water will also expand if it warms, contributing further to the rise of sea level.
• The earth will become warmer on average. While certain regions may welcome warmer temperatures, some won't.
• Warmer conditions will likely lead to more precipitation and evaporation overall. However, individual regions will vary, some becoming dryer and others wetter.
• Meanwhile, crops and some other plants may favorably respond to increased atmospheric carbon dioxide, using water more efficiently and growing more vigorously. Simultaneously, shifting climate patterns and higher temperatures may change the regions where crops influence the makeup of natural plant communities and grow best.

Gases contributing to the greenhouse effect comprise:

· Nitrous oxide: Being one of the most powerful greenhouse gases, it is produced by the practices of soil cultivation.

· Water power: This greenhouse gas is the most abundant. More importantly, it acts as climate feedback. As the atmosphere of the earth warms, water vapor increases, but so does the possibility of precipitation and clouds, making these come off as the fundamental feedback mechanisms to the greenhouse effect.

· CFCs (or chlorofluorocarbons): As for synthetic compounds of entirely industrial origin, CFCs are used in a variety of applications but now usually regulated in production and release to the atmosphere by international agreement for their ability to contribute to the ozone layer destruction. Of course, these are also categorized as greenhouse gases.

· Carbon dioxide: It's a minor yet important component of the atmosphere. It's released as a result of natural processes like volcano eruptions and respiration and through human activities such as burning fossil fuels, land-use changes, and deforestation. Since the start of the Industrial Revolution, humans have increased the concentration of carbon dioxide by more than a third.

· Methane: A hydrocarbon gas produced both through human activities and natural resources, including the decomposition of wastes in agriculture, landfills, rice cultivation, along with manure management and ruminant digestion with domestic livestock. Methane is a far more active greenhouse than carbon dioxide on a molecule-for-molecule basis. It's also the one which is far less abundant in the atmosphere.

Solar irradiance

One major cause of climate change is the changes in the sun's energy because the sun is the prime source of energy that drives our climate system.

Indeed, studies point out that the role of solar variability cannot be ignored in the climate changes of the past. For instance, an increase in volcanic activity coupled with solar activity is thought to have helped trigger the Little Ice Age between roughly 1650-1850, when Greenland cooled from 1410-1720s and glaciers advanced in the Alps.

However, numerous lines of evidence demonstrate that existing global warming is inexplicable by changes in energy from the sun:

• If a more active sun were causing warming, the scientists would expect to witness warmer temperatures in every layer of the atmosphere. Instead, they've observed cooling in the upper atmosphere and warming in the lower parts of the atmosphere and at the surface.
• The amount of energy coming from the sun since 1750 either increased slightly or remained constant on average.
• The climate models inclusive of solar irradiance changes can't reproduce the observed temperature trend over more than the past century, including a rise in greenhouse gas.

How human activity comes into the picture?

The Intergovernmental Panel on Climate Change published its Fifth Assessment Report, where a group of 1300 in self-governing scientists from countries around the globe were under the auspices of the UN (or United Nations). The report concluded that the likelihood of human activities warming the planet for the past 50 years is over 95%.

In the last 150 years, the industrial activities that our modern civilization looks up to have increased atmospheric carbon dioxide levels from 280 to 400 parts per million. The report also concluded that there's a 95% likelihood that greenhouse gases like nitrous oxide, methane, and carbon dioxide are produced by humans and have caused much of the observed increase in the temperatures of earth over the last 50 years.