Climate change is the change that takes place in the climate pattern over decades or centuries. The term refers to both natural and human-induced changes. Climate change may be due to natural internal processes or external forcings, or to persistent anthropogenic changes in the composition of the atmosphere or in land use.
 Why should I be aware of this?
Climate change will affect human settlements in one of three major ways:
- The economic sectors that support the settlement are affected because of changes in resource productivity or changes in market demand for the goods and services produced there.
- Some aspects of physical infrastructure (including energy transmission and distribution systems), buildings, urban services (including transportation systems), and specific industries (such as agro industry, tourism, and construction) may be directly affected.
- Populations may be directly affected through extreme weather, changes in health status, or migration. The problems are somewhat different in the largest (<1 million) and mid- to small-sized population centers.
 Climate change and health
Climate change will be accompanied by an increase in heat waves, increased humidity and urban air pollution, which would cause an increase in heat-related deaths and illness. There are indications that the impact would be greatest in urban populations, affecting particularly the elderly, sick, and those without access to air-conditioning.
Most predictive model studies have indicated that malaria and dengue-two vector-borne infections – would spread to greater geographic areas. Many vector-, food-, and water-borne infectious diseases are known to be sensitive to changes in climatic conditions.
 All about climate change
As carbon dioxide, methane, nitrous oxide, and other greenhouse gases continue to be released into the atmosphere, global temperatures will keep rising. The effects of climate change will vary by region, over time, and with the ability of different societal and environmental systems to adapt to or cope with the change.
 Effects of climate change
Scientists from around the world tell us that during the past 100 years, the world's surface air temperature increased an average of 0.6° Celsius (1.1°F). Though this may not sond very much, a difference of one degree can affect the earth, as can be seen from the following results:
- During the 20th century, sea level rose about 15 cm (6 inches) due to melting glacier ice and expansion of warmer seawater. Models predict that sea level may rise as much as 59 cm (23 inches) during the 21st Century, threatening coastal communities, wetlands, and coral reefs.
- Arctic sea ice is melting. The summer thickness of sea ice is about half of what it was in 1950. Melting ice may lead to changes in ocean circulation. Plus melting sea ice is speeding up warming in the Arctic.
- Glaciers and permafrost are melting. Over the past 100 years, mountain glaciers in all areas of the world have decreased in size and so has the amount of permafrost in the Arctic. Greenland's ice sheet is melting faster too.
 other impacts
- Climate change is only one aspect of global change. The introduction of exotic pests such as the Asian long-horned beetle and the pine shoot beetle is accelerating with increased trade. These introduced species pose a significant threat to our forests. The increased number of extreme climatic events makes ecosystems more vulnerable to a greater number of pests.
- Northern regions are likely to be most affected by the warmer climate that is projected for the coming decades.
- An increase in temperature would reduce the size of caribou herds through the destruction of winter habitats by summer forest fires.
- Wildlife is sensitive to climate variations. The results of recent studies show that any change in summer climatic conditions would likely cause rapid advances or retreats of certain populations as their habitats shift or are disturbed.
- The twentieth century was the warmest century of the last 1000 years, and the 1990s was the warmest decade of that century.
- Human activity is currently responsible for emitting 30 million tons of CO2 each year, 12 million tons of which accumulate in the atmosphere.
- Mackerel, a warm-water fish species, has been found in recent years in the waters off Vancouver Island. There is concern that mackerel may eat young salmon, further depleting stocks.
- Climate models predict the greatest warming to occur in Arctic regions.
- Heavy rains and snowfalls are predicted to increase in frequency and intensity
- Venus, our planetary neighbour, has an atmosphere that is 98% carbon dioxide. Due to the extreme greenhouse effect, temperatures reach 430°C.
- 9000 years ago, average temperatures in southern British Columbia were 1° to 2° C warmer than today.
- Warmer spring temperatures have already lengthened the Okanagan growing season. McIntosh apples at Summerland, British Columbia, usually bloom in May. However, of the eight times since 1937 when they have bloomed earlier, five have occurred since 1987.
- In the Sanikiluaq area, recent cooling trends have resulted in more ice cover and the eider duck population, which depends on open water for food and warmth, has been suffering.
- The permafrost boundary is expected to move north by several hundred kilometers.
- Permafrost forms an impermeable layer for mine tailings and landfill sites. A loss of this layer could increase the risk of contamination to soil and water.
- Warmer temperatures will thaw traditional ice cellars making them useless for storing meat.
- Climate Change Impacts and Adaptation Program
- Scientific Facts on Climate Change