What is Climate Change ?
Climate, refers to the average weather of an area over more than thirty years.
While the weather can change in just a few hours, the climate changes over longer timeframes. Climate change is a significant variation of average weather conditions becoming, for example, warmer, wetter, or drier—over several decades or longer. It’s the longer-term trend that differentiates climate change from natural weather variability.
Observed changes over the 20th century include increases in global air and ocean temperature, rising global sea levels, long-term sustained widespread reduction of snow and ice cover, and changes in atmospheric and ocean circulation as well as regional weather patterns, which influence seasonal precipitation and temperature conditions. These changes are caused by extra heat in the climate system due to the addition of greenhouse gases to the atmosphere. These additional greenhouse gases are primarily input by human activities such as the burning of fossil fuels (coal, oil, and natural gas), agriculture, and land clearing. These activities increase the amount of ‘heat-trapping’ greenhouse gases in the atmosphere. The pattern of observed changes in the climate system is consistent with an increased greenhouse effect. Other climatic influences such as volcanoes, the sun and natural variability cannot alone explain the timing and extent of the observed changes. Today, climates are changing.
The science behind climate change is supported by extensive scientific research performed and reported across the world. Past and present climate information is collected from observations and measurements of the environment. Climate models are used to understand the causes of climate change and to project changes into the future.