Global WarmingGlobal Warmingand Climate Changeand Climate Change

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TruthTruthThe globe is warming.The globe is warming.

ConsequencesConsequences

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

Extreme Weather: Heat Extreme Weather: Heat WavesWavesA heat wave is a prolonged period of A heat wave is a prolonged period of

excessively hot weather, which may result excessively hot weather, which may result in crop failures and deaths from in crop failures and deaths from hyperthermia (heat stroke).hyperthermia (heat stroke).

The 2003 European heat wave killed an estimated 35,000 people.

Extreme Weather: DroughtExtreme Weather: Drought

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

Extreme Weather: WildfiresExtreme Weather: Wildfires

Heat waves and drought conditions Heat waves and drought conditions also contribute to wildfires.also contribute to wildfires.

2009 wildfires in Kelowna, British Columbia forced the evacuation of 17,000 people.

Positive Feedback LoopsPositive Feedback Loops

The consequences of global warming can The consequences of global warming can accelerate global warming further. This is accelerate global warming further. This is called a called a positive feedback looppositive feedback loop..

E.g. wildfires add greenhouse gases to the E.g. wildfires add greenhouse gases to the atmosphere and remove carbon sinks.atmosphere and remove carbon sinks.

Positive Feedback LoopsPositive Feedback LoopsThe thawing of permafrost resulting in The thawing of permafrost resulting in

methane emissions is another example of methane emissions is another example of a positive feedback loop.a positive feedback loop.

Positive Feedback LoopsPositive Feedback Loops

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

Extreme Weather: StormsExtreme Weather: Storms

Global warming can also lead to Global warming can also lead to increased evaporation and more increased evaporation and more intense storms.intense storms.

Hurricane Katrina strikes New Orleans, Aug 2005

Extreme Weather: FloodingExtreme Weather: Flooding

These storms can result in flooding, These storms can result in flooding, particularly in areas that have suffered particularly in areas that have suffered deforestation or have developed water deforestation or have developed water catchment areas.catchment areas.

July 2010 flash flooding in Montreal

Meltwater FloodingMeltwater Flooding

Rapid melting in spring of excess Rapid melting in spring of excess winter precipitation can also cause winter precipitation can also cause extreme flooding.extreme flooding.

Flooding by the Red River in North Dakota, 2009

Loss of Glacial RunoffLoss of Glacial RunoffMelting of glaciers has resulted in smaller Melting of glaciers has resulted in smaller

glaciers, resulting in reduced runoff – a glaciers, resulting in reduced runoff – a problem for many people around the world problem for many people around the world who depend on runoff for their water supply who depend on runoff for their water supply (and hydroelectric power).(and hydroelectric power).

Mount Kilimanjaro ice cover

Loss of Glacial RunoffLoss of Glacial RunoffMelting of glaciers has resulted in smaller Melting of glaciers has resulted in smaller

glaciers, resulting in reduced runoff – a glaciers, resulting in reduced runoff – a problem for many people around the world problem for many people around the world who depend on runoff for their water supply who depend on runoff for their water supply (and hydroelectric power).(and hydroelectric power).Mount Kilimanjaro ice cover

Loss of Glacial RunoffLoss of Glacial RunoffThis is a particular problem in the This is a particular problem in the

Himalayas, since Himalayas, since 40% of the world’s 40% of the world’s populationpopulation is dependent on the rivers that is dependent on the rivers that drain the Himalayas.drain the Himalayas.

Global Sea Level RiseGlobal Sea Level RiseSome areas like Some areas like

Bangladesh, however, Bangladesh, however, are at greater risk from are at greater risk from rising sea levels, which rising sea levels, which are caused by melting are caused by melting of the ice caps, e.g. of the ice caps, e.g. over Greenland.over Greenland.

Global Sea Level RiseGlobal Sea Level Rise

Slow Ocean CurrentsSlow Ocean CurrentsFreshwater meltwater also affects the Freshwater meltwater also affects the

mechanism that drive ocean mechanism that drive ocean currents; it is predicted that ocean currents; it is predicted that ocean currents will slow down to about ½ currents will slow down to about ½ their current speed over the next their current speed over the next century.century.

Ocean Ocean WarmingWarming

Ocean warming is a Ocean warming is a problem not only problem not only because it because it produces more produces more intense hurricanes intense hurricanes and because the and because the expanded water expanded water causes further causes further rises in sea levels rises in sea levels but also because but also because warmer water warmer water absorbs less COabsorbs less CO22 – – another positive another positive feedback loop.feedback loop.

Ocean WarmingOcean Warming

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

Threatened SpeciesThreatened SpeciesAbout 40-70% of all species are at risk of About 40-70% of all species are at risk of

extinction if the global temperature extinction if the global temperature increases by only 3.3increases by only 3.3ooC.C.

Not-So-Threatened SpeciesNot-So-Threatened SpeciesThough some species seem to be increasing Though some species seem to be increasing

their populations and expanding their their populations and expanding their ranges, such as jellyfish and malaria-ranges, such as jellyfish and malaria-carrying mosquitoes.carrying mosquitoes.

Range Shifts and Cycle Range Shifts and Cycle ChangesChangesMany animals are shifting their ranges Many animals are shifting their ranges

northward and plants are northward and plants are germinating earlier.germinating earlier.

Awareness and ActionAwareness and ActionFortunately there is now public awareness Fortunately there is now public awareness

and increasing public acceptance that and increasing public acceptance that global warming exists and has dramatic global warming exists and has dramatic consequences. The next step is action.consequences. The next step is action.

http://www.ted.com/talks/lang/eng/al_gore_s_new_thinking_on_the_climate_crisis.html

http://www.ted.com/talks/lang/eng/al_gore_warns_on_latest_climate_trends.html

More practiceMore practice

Read pages 373-378Read pages 373-378

Answer questions on Answer questions on

p. 378 #1, 3 – 6p. 378 #1, 3 – 6