Global Warming
Greenhouse Gases and Climate
Is the climate becoming warmer and warmer?
According to the National Academy of Sciences, the Earth's surface temperature has risen by about 1 degree Fahrenheit in the past century, with accelerated warming during the past two decades. There is new and stronger evidence that most of the warming over the last 50 years is attributable to human activities. Human activities have altered the chemical composition of the atmosphere through the buildup of greenhouse gases – primarily carbon dioxide, methane, and nitrous oxide. The heat-trapping property of these gases is undisputed although uncertainties exist about exactly how earth's climate responds to them. (source:US-EPA)
Global temperature trend Note that these are surface temperatures and mostly overland. The temperature in upper levels may be different, even reversed.
Source: UK Met Office
What cause the temperature of the atmosphere to go up?
There are many possible mechanisms that can cause the warming of the atmosphere, for example:
Natural variation – the climate becomes warmer by internal chaotic dynamics of the earth-atmosphere system (that is, no external influence).
Solar activity – either direct increase of solar energy output or indirect “trigger” mechanisms due to solar activity (though nobody knows how) may cause the surface temperature to go up.
Greenhouse effect – increasing “greenhouse” gases such as CO2, CH4, NO, CFC,…etc. (actually H2O is very efficient, too, but at
Global Warming
Greenhouse Gases and Climate
Is the climate becoming warmer and warmer?
According to the National Academy of Sciences, the Earth's surface temperature has risen by about 1 degree Fahrenheit in the past century, with accelerated warming during the past two decades. There is new and stronger evidence that most of the warming over the last 50 years is attributable to human activities. Human activities have altered the chemical composition of the atmosphere through the buildup of gree..