Global Warming and Climate Change SNC2D

Truth The globe is warming.

Consequences So what are the possible consequences (to the climate and the Earth’s ecosystems) of global warming?

Extreme Weather: Heat Waves A heat wave is a prolonged period of excessively hot weather, which may result in crop failures and deaths from hyperthermia (heat stroke). The 2003 European heat wave killed an estimated 35,000 people.

Extreme Weather: Drought Areas near deserts (e.g. much of Australia) are particularly vulnerable to drought.

Extreme Weather: Wildfires Heat waves and drought conditions also contribute to wildfires wildfires in Kelowna, British Columbia forced the evacuation of 17,000 people.

Positive Feedback Loops The consequences of global warming can accelerate global warming further. This is called a positive feedback loop. E.g. wildfires add greenhouse gases to the atmosphere and remove carbon sinks.

Positive Feedback Loops The thawing of permafrost resulting in methane emissions is another example of a positive feedback loop.

Positive Feedback Loops... as is the melting of Arctic sea ice (and decreased ice cover over the Great Lakes), resulting in lowered albedo.

Extreme Weather: Storms Global warming can also lead to increased evaporation and more intense storms. Hurricane Katrina strikes New Orleans, Aug 2005

Extreme Weather: Flooding These storms can result in flooding, particularly in areas that have suffered deforestation or have developed water catchment areas. July 2010 flash flooding in Montreal

Meltwater Flooding Rapid melting in spring of excess winter precipitation can also cause extreme flooding. Flooding by the Red River in North Dakota, 2009

Loss of Glacial Runoff Melting of glaciers has resulted in smaller glaciers, resulting in reduced runoff – a problem for many people around the world who depend on runoff for their water supply (and hydroelectric power). Mount Kilimanjaro ice cover

Loss of Glacial Runoff Melting of glaciers has resulted in smaller glaciers, resulting in reduced runoff – a problem for many people around the world who depend on runoff for their water supply (and hydroelectric power). Mount Kilimanjaro ice cover

Loss of Glacial Runoff This is a particular problem in the Himalayas, since 40% of the world’s population is dependent on the rivers that drain the Himalayas.

Global Sea Level Rise Some areas like Bangladesh, however, are at greater risk from rising sea levels, which are caused by melting of the ice caps, e.g. over Greenland.

Global Sea Level Rise

Slow Ocean Currents Freshwater meltwater also affects the mechanism that drive ocean currents; it is predicted that ocean currents will slow down to about ½ their current speed over the next century.

Ocean Warming Ocean warming is a problem not only because it produces more intense hurricanes and because the expanded water causes further rises in sea levels but also because warmer water absorbs less CO 2 – another positive feedback loop.

Ocean Warming Warmer water is also not ideal for photosynthesizing plankton – another carbon sink and the basis of marine food webs.

Threatened Species About 40-70% of all species are at risk of extinction if the global temperature increases by only 3.3 o C.

Not-So-Threatened Species Though some species seem to be increasing their populations and expanding their ranges, such as jellyfish and malaria-carrying mosquitoes.

Range Shifts and Cycle Changes Many animals are shifting their ranges northward and plants are germinating earlier.

Awareness and Action Fortunately there is now public awareness and increasing public acceptance that global warming exists and has dramatic consequences. The next step is action.