causes_of_climate_change(课堂演讲).pptx

Causes of climate changeWhat is climate change?Climate change represents a shift (upwards or downwards) in the magnitude of the atmospheric variables (temperature, precipitation etc) from the long established pattern for a given location. Climate Change is increasingly becoming an important consideration of our lives. Scientists believe that there are evidences all around us that the Earths climate has been undergoing noticeable changes. The causes of climate change can be divided into two categories natural causes those that are created by man.Continental drift Back then, the earth was not as we see it today, but the continents were all part of one large landmass. Impact on the climate: physical features of the landmass, their position and the position of water bodies. the flow of ocean currents and windsNatural causes Volcanoes large volumes of sulphur dioxide (SO2), combines with water to form tiny droplets of sulphuric acid water vapour, dust, and ash into the atmosphere. the large volumes of gases and ash can influence climatic patterns for yearsEg: Mount Pinatoba /Tambora Volcanic eruptions can reduce the amount of solar radiation reaching the Earths surface, lowering temperatures in the lower levels of the atmosphere (called the troposphere), and changing atmospheric circulation patterns. The earths tiltThe earth makes one full orbit around the sun each year. It is tilted at an angle of 23.5° to the perpendicular plane of its orbital path. If there was no tilt we would not have experienced seasons. The earths axis in fact it changes. This gradual change in the direction of the earths axis, called precession is responsible for changes in the climate.Ocean currents ------a major component of the climate systemThey cover about 71% of the Earth and absorb about twice as much of the suns radiation as the atmosphere or the land surface. Ocean currents move vast amounts of heat across the planet region that is strongly influenced by ocean currents:The coast of Per