What is Climate Change?
Climate change is a change in the "average weather" that a given region experiences. Average weather includes all the features we associate with the weather such as temperature, wind patterns and precipitation.
When we speak of climate change on a global scale, we are referring to changes in the climate of the Earth as a whole. The rate and magnitude of global climate changes over the long term have many implications for natural ecosystems.
As human societies adopt increasingly sophisticated and mechanized lifestyles, the amounts of heat-trapping gases in the atmosphere have been increased. By increasing the amount of these gases, humankind has enhanced the warming capability of the natural greenhouse effect. It is the human-induced enhanced greenhouse effect that causes environmental concern. It has the potential to warm the planet at a rate that has never been experienced in human history.
The Earth is Getting Warmer
Modern temperature records only go back to about 1860. But scientists study sediment cores from the bottoms of oceans and lakes, tree rings, glacier ice cores, and other data sources to learn about changes in climate over thousands of years.
An international scientific consensus has emerged that our world is getting warmer. Abundant data demonstrate that global climate was warmed during the past 150 years. The increase in temperature was not constant, but rather consisted of warming and cooling cycles at intervals of several decades. Nonetheless, the long term trend is one of net global warming. Corresponding with this warming, alpine glaciers have been retreating, sea levels have risen, and climatic zones are shifting.
- The 1980s and 1990s are the warmest decades on record, with 1998 the warmest year
- The 10 warmest years in global meteorological history have all occurred in the past 15 years
- The 20th century has been the warmest globally in the past 1000 years.
Climate scientists around the world agree that average global temperatures could rise by 1.4 to 5.8 degrees Celsius by the end of this century. This increase will not be distributed evenly around the globe; in Canada, this could mean an increase in annual mean temperatures in some regions of more than 5 degrees.
Climate change is more than a warming trend. Increasing temperatures will lead to changes in many aspects of weather, such as wind patterns, the amount and type of precipitation, and the types and frequency of severe weather events that may be expected to occur. Such climate change could have far-reaching and/or unpredictable environmental, social and economic consequences.
A natural system known as the "greenhouse effect" regulates the temperature on earth. Human activities have the potential to disrupt the balance of this system.