Climate:

Climate change is a long-term shift in the climate of a specific location, region or planet. The shift is measured by changes in features associated with average weather, such as temperature, wind patterns and precipitation. What most people don’t know is that a change in the variability of climate is also considered climate change, even if average weather conditions remain the same.

Climate change occurs when the climate of a specific area or planet is altered between two different * periods of time. This usually occurs when something changes the total amount of the sun’s energy absorbed by the earth’s atmosphere and surface. It also happens when something changes the amount of heat energy from the earth’s surface and atmosphere that escapes to space over an extended period of time.

Such changes can involve both changes in average weather conditions and changes in how much the weather varies around these averages. The changes can be caused by natural processes like volcanic eruptions, variations in the sun’s intensity, or very slow changes in ocean circulation or land surfaces which occur on time scales of decades, centuries or longer.

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But humans also cause climates to change by releasing greenhouse gases and aerosols into the atmosphere, by changing land surfaces, and by depleting the stratospheric ozone layer. Both natural an’ human factors that can cause climate change are called ‘climate forcings’, since they push, or ‘force’ the’ climate to shift to new values.

Climate change refers to a statistically significant variation in either the mean state of the climate or in its variability, persisting for an extended period (typically decades or longer). Climate change may be due to natural internal processes or external forcing, or to persistent anthropogenic changes in the composition of the atmosphere or in land use.

Climate change is commonly used to describe any systematic alteration or statistically significant variation in either the average state of the climate elements such as precipitation, temperature, winds, or pressure; or in its variability, sustained over a finite time period (decades or longer). It can be referred to as the long-term change in global weather patterns, associated especially with increases in temperature, precipitation, and storm activity.

The work of climatologists has found evidence to suggest that only a limited number of factors are primarily responsible for most of the past episodes of climate change on the Earth. These factors can categorize into two broad categories:

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A. Natural Causes of Climate Change:

1. Variations in the Earth’s orbital characteristics (Milankovitch theory).

2. Volcanic eruptions

3. Variations in solar output

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4. Change in composition of atmosphere

B. Anthropogenic Causes of Climate Change

1. Green house gas emission

I. carbon dioxide

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II. Methane

HI. CFCs

IV. Nitrogen Oxide

V. Water Vapour

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2. Industrialization

3. Deforestation

EI Nino and La Nino

El-Nino is a warm ocean current that flows along the equator from the date line and south off the co- of Ecuador at Christmas time. The water along the barren coast of Peru is cold and flow northward .lug most of the year, but around Christmas time, they are warm and flow southward. The latter current was originally given the name El-Nino, Spanish term for “the boy.” Because of its timing, and because it is associated with refreshing rains, the name also refers to Child Jesus.

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Every few years the current is exceptionally intense and persistent, bringing very heavy rains that transform parts of the coastal desert into a garden. At such times the fish that usually are abundant in the cold water, disappear temporarily.

Today, the term El Nino is reserved for these inter annual events which now are perceived as disasters even though they originally were welcomed as blessings. El Nino was originally regarded as a regions phenomenon, confined to the shores of Peru, but is now recognized as part of the changes in oceanic conditions across the entire tropical Pacific Ocean.

Furthermore, El Nino is not a sporadic departure from “normal” conditions, but is one phase of a continual oscillation with a period of 3 to 5 years; the complementary phase is known as La Nina. (This oscillation is evident in a record of sea surface temperature variations in the eastern equatorial Pacific over the past century.

Early in the 20th century, Gilbert Walker’s attempts to predict failures of the monsoons in India led to his discovery of the Southern Oscillation, which includes oscillations in the intensity of the trade winds over the tropical Pacific. Those oscillations, it turns out, are the ones that induce El Nino and La Nina. From a meteorological perspective, the changes in the wind patterns are a consequence of the changes in the sea surface temperature patterns associated with El Nino and La Nina.

This circular argument-sea surface temperature changes are both the cause and the consequence of changes in the winds-implies that interactions between the ocean and atmosphere are at the heart of the matter. Those interactions are unstable, capable of amplifying small, random disturbances, such as a burst of strong winds, into a major climate fluctuation.