Climate Change - The Basics
Climate Change Definition
Climate change is defined as a considerable change in weather patterns over a longer period of time which can last from a few decades to a few millions years. It may involve a change of weather patterns in general or a change in distribution of weather such as increased occurrence of extreme weather events. As opposed to the normal daily weather changes and seasonal variations, climate change is a result of changes in the factors such as changing ocean currents, plate tectonics, changes in the intensity of solar radiation, volcanic activity and human activity. The latter has been shown to be responsible for the current climate change. Evidence of Climate Change
The scientific community agrees that there is no doubt that the Earth’s climate is changing and that human activities such as fossil fuel burning and deforestation. They also agree that these are the number one cause of rising levels of greenhouse gases in the atmosphere which in turn are warming our planet. The scientists know that from a number of indicators that reveal significant and lasting changes in climate patterns when compared to normal climate variations in the Earth’s past. Indicators of climate change include:
-
Average global temperature. Over the last 100 years, the Earth’s average (surface) temperature increased for about 0.75 degrees Celsius with the average temperature rise being nearly double in the last 50 years. This may not seem a lot, however, a rise of average global temperature for about 4 degrees Celsius is thought to be fatal for most forms of life on the planet including humans.
-
Historical and archaeological records. They offer a valuable insight into the past climate variations and their effect on human population. But they also reveal that climate has been relatively stable throughout recorded history until the mid-19th century.
-
Glaciers. They are extremely sensitive to temperature changes and can either shrink or grow, depending on temperature variability and changes in precipitation. Strong glacier retreat from the mid-1980s thus clearly reveal that the Earth’s temperature is rising.
-
Arctic sea ice. Satellite data shows that the Greenland ice sheet – sea ice that does not melt away during the summer is declining at a rapid pace. The ice minimum in the Arctic in 2012 was about one half of the average between 1979 and 2000. It is predicted that the Arctic will be free of summer ice before year 2100.
-
Global sea level rise. The data reveals that the average global sea level is rising since the mid-20th century. From 1950 to 2009, the sea level rose for about 1.7 mm per year but it rose for about 3.3 mm per year between 1993 and 2009.
-
Ice cores. Samples of ice cores from ice sheers such as the Antarctic ice sheet hold valuable information about variations in global sea level as well as CO2 levels in the atmosphere. The latter can be measured in the air bubbles that are trapped in ice cores.
-
Other. A variety of other indicators support the findings of the scientists about climate change. Examples include changes in vegetation patterns, distribution of pollen (palynology) and precipitation, to mention only a few.