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Climate Change Portal

This Climate Change Portal was set up by the Bureau of Agricultural Research to provide researchers, policy makers and development practitioners with a ready assembly of climate and climate-related literature. Maintained by the Bureau of Agricultural Research, this website contains information on the characteristics and impacts of climate change that have been gathered by its technical staff from local and foreign sources. Through this portal, BAR seeks to enhance the quality of discussions on climate change particularly where Philippine agriculture is affected.

What is Global Climate change?

Global climate change is caused by the accumulation of greenhouse gases in the lower atmosphere. The global concentration of these gases is increasing, mainly due to human activities, such as the combustion of fossil fuels (which release carbon dioxide) and deforestation (because forests remove carbon from the atmosphere). The atmospheric concentration of carbon dioxide, the main greenhouse gas, has increased by 30 percent since preindustrial times.

It is estimated that global mean surface temperature will rise by 1.5-3.5 C by 2100. This rate of warming is significant. Large changes in precipitation, both increases and decreases, are forecast, largely in the Tropics. Climate change is very likely to affect the frequency and intensity of weather events (e.g. storms, floods) around the world. Climate change will also cause sea level to rise due to thermal expansion of the oceans and the melting of mountain glaciers. Global mean sea level is anticipated to rise by 15-95 cm by 2100. Sea level rise will increase vulnerability to coastal flooding and storm surges. Many countries will be able to maintain coastal defenses but some developing country populations and small island states are extremely vulnerable.

The faster the climate changes, the greater will be the risk of damage to our environment. Climatic zones (and thus ecosystems and agricultural zones) could shift towards the poles by 150-550 km by 2100. Many ecosystems may decline or fragment, and individual species may become extinct.

What causes climate change?

Most scientists agree the main cause of the current global warming trend is human expansion of the "greenhouse effect" -- warming that results when the atmosphere traps heat radiating from Earth toward space.

Certain gases in the atmosphere behave like the glass on a greenhouse, allowing sunlight to enter, but blocking heat from escaping. Long-lived gases, remaining semi-permanently in the atmosphere, which do not respond physically or chemically to changes in temperature are described as "forcing" climate change whereas gases, such as water, which respond physically or chemically to changes in temperature are seen as "feedbacks."

Gases that contribute to the greenhouse effect include:

Water vapor. The most abundant greenhouse gas, but importantly, it acts as a feedback to the climate. Water vapor increases as the Earth's atmosphere warms, but so does the possibility of clouds and precipitation, making these some of the most important feedback mechanisms to the greenhouse effect.

Carbon dioxide (CO2). A minor but very important component of the atmosphere, carbon dioxide is released through natural processes such as respiration and volcano eruptions and through human activities such as deforestation, land use changes, and burning fossil fuels. Humans have increased atmospheric CO2 concentration by a third since the Industrial Revolution began. This is the most important long-lived "forcing" of climate change.

Nitrous oxide. A powerful greenhouse gas produced by soil cultivation practices, especially the use of commercial and organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning.

Chlorofluorocarbons (CFCs). Synthetic compounds of entirely of industrial origin used in a number of applications, but now largely regulated in production and release to the atmosphere by international agreement for their ability to contribute to destruction of the ozone layer. They are also greenhouse gases .

On Earth, human activities are changing the natural greenhouse. Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). This happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2. To a lesser extent, the clearing of land for agriculture, industry, and other human activities have increased concentrations of greenhouse gases.


Sources:
http://climate.nasa.gov/causes/
https://apps.who.int/peh/climate/climate_change.html