Summary

In this Study Session, you have learned that:

• The climate is the average weather experienced over months or years and climate variability is the short-term fluctuations around the expected average weather.
• Climate change refers to widespread, rapid changes in the global climate since the beginning of the 20th century, which have been increasing at a faster rate in recent decades.
• One driver of climate change is global warming: the global average surface land and ocean temperature has increased by about 0.74 ºC in the century between 1905 and 2005; climate change also includes alterations in wind patterns, ocean currents and the distribution of rainfall.
• Natural causes of climate change include fluctuations in solar activity and volcanic eruptions. The major human cause of climate change is the increasing release of greenhouse gases (carbon dioxide, methane and nitrous oxide) into the atmosphere.
• Greenhouse gases act like the glass in a greenhouse by reflecting radiated heat back towards the Earth, trapping more of the sun’s energy and causing the surface temperature to rise.
• Global warming is causing sea levels to rise as ice and snow cover decreases and melted water runs into the oceans.