Global warming definition, causes and effects pdf

The Earth’s Climate Climate change is altering temperature, precipitation, and sea levels, and will adversely impact human and natural systems, including water resources, human settlements and health, ecosystems, and biodiversity. The unprecedented acceleration of climate change over the last 50 years and the increasing confidence in global climate models add to the compelling evidence that climate is being affected by greenhouse gas (GHG) emissions from human activities. 2 Changes in climate should not be confused with changes in weather. Weather is observed at a particular location on a time scale of hours or days, and exhibits a high degree of variability, whereas climate is the long-term average of short-term weather patterns, such as the annual average temperature or rainfall. 3 Under a stable climate, there is an energy balance between incoming short wave solar radiation and outgoing long wave infrared radiation. Solar radiation passes through the atmosphere and most is absorbed by the Earth’s surface. The surface then re-emits energy as infrared radiation, a portion of which escapes into space. Increases in the concentrations of greenhouse gases in the atmosphere reduce the amount of energy the Earth’s surface radiates to space, thus warming the planet. 4 The Earth's Greenhouse Effect 1 Climate Forcings • Disturbances of the Earth’s balance of incoming and outgoing energy are referred to as positive or negative climate forcings. Positive forcings, such as GHGs, exer...