Perhaps the most serious challenge to sustainability is the fact that the Earth's climate is rapidly changing. The eight warmest years on record since 1850 have all been after 1998. In the last 100 years, the average surface temperature has increased by 1.2°F to 1.4°F. Warmer temperatures have already affected precipitation patterns, snow and ice cover, and sea levels.
Scientists attribute most of the recent and dramatic changes in climate to human activities, particularly the burning of fossil fuels and deforestation, which have caused a significant increase of "greenhouse gases" in our atmosphere. These gases — including carbon dioxide, water vapor, nitrous oxide, methane, and ozone — act like the glass panes of a greenhouse, trapping the sun’s heat and causing surface temperatures to warm.
Climate change is a prime illustration of the ways that natural patterns such as cycles and feedback loops work (for example, warmer temperatures increase the thawing of permafrost, which releases methane trapped in the permafrost, which reinforces the greenhouse effect, which further raises temperatures, and so on).
Much of the life on Earth today depends on the greenhouse gases that occur naturally in our atmosphere. For instance, plants require carbon dioxide for photosynthesis. Without greenhouse gases, the planet’s surface temperatures would be much colder. However, since the industrial age, significantly increased amounts of these gases have been added to the atmosphere. The level of carbon dioxide alone has increased by over 30 percent.
If current trends continue, climate models predict that the average surface temperature could increase 2°F to 7°F by the year 2100. It is difficult to foresee what the exact effects of such a change would be, especially as they will likely vary by region and over time.
Some changes such as milder temperatures in cold regions and longer growing seasons may be good for people and other life forms in some places. A long list of potential other changes, though, points to devastating consequences: heat-related health problems, air pollution, changes in food and water supplies, coastal flooding, erratic and unpredictable weather, severe alteration of the habitats some animals depend on, disruption of coevolved patterns such as the timing of animals' hibernations and the blossoming of the plants they eat, and interruption of global flows of ocean currents, to name just a few.
As a result of warmer temperatures, scientists have already observed shrinking glaciers and ice sheets, thawing permafrost, later frosts, earlier flowering of trees, longer growing seasons, and changes in plant and animal ranges. Climate change is beginning to impact agriculture, human health, water availability, and land patterns.
Climate change is a complex phenomenon around which there is much misunderstanding and political controversy. It offers educators an opportunity to introduce systems thinking about an issue that matters greatly with respect to sustainabilty.
Schools' practices around energy conservation and procurement create additional opportunities for hands-on learning related to understanding the effect of human activity on climate.