Climate Control and Ozone Depletion. Chapter 19

Transcription

1 Climate Control and Ozone Depletion Chapter 19

2 Global Warming and Global Cooling Are Not New Over the past 4.5 billion years the climate has been altered by Volcanic emissions Changes in solar input Movement of the continents Impacts by meteors Over the past 900,000 years Global Cooling and Global Warming Glacial and interglacial (between ice ages) periods Over the past 10,000 years Interglacial period-- stable climate and avg. Global surface temp Allowed agriculture and cities to flourish Over the past 1,000 years Temperature stable until we clear cut forests and burn fossil fuels Over the past 100 years Temperature changes methods of determination-radioisotopes in rocks, fossils and ocean sediment, boreholes, tree rings, etc

3 Estimated Changes in the Average Global Temperature of the Atmosphere

4 Our Climate, Lives, and Economies Depend on the Natural Greenhouse Effect Solar energy and the greenhouse effect warm the earth s lower atmosphere and surface Without the natural greenhouse effect Cold, uninhabitable earth 1% of lower atmosphere is made of greenhouse gases (water vapor, CO 2, CH 4, and N 2 O) 1896 Arrhenius first recognized greenhouse effect Ice Cores Are Extracted by Drilling Deep Holes in Ancient Glaciers

5 Human Activities Emit Large Quantities of Greenhouses Gases Since the Industrial Revolution (275 years ago) CO 2, CH 4, and N 2 O emissions higher Main sources: agriculture, deforestation, and burning of fossil fuels Correlation of rising CO 2 and CH 4 with rising global temperatures CO 2 has risen from 280 ppm to 384 ppm

6 GREENHOUSE GASES CARBON DIOXIDE METHANE NITROUS OXIDE (N2O) CFCs WATER VAPOR

7 Greenhouse Gases CO 2 most abundant greenhouse gas (GHG) Sources: burning fossil fuels, deforestation Ice cores have shown that CO 2 increasing in atmosphere 35% higher than pre-industrial Rev. Natural cycling of CO 2 levels Seasonal shift in CO 2 production; high fall; low spring Ocean acts as sink, absorbing large amounts. Vegetation acts as a sink (until it dies or is cut down) Stays in the atmosphere

8 Other Greenhouse Gases Methane (CH 4 ) 21 times more warming effect than CO 2 and increasing at 8 times the rate. Atmospheric lifetime= 12 years Methane production is faster than what is being broken down Main sources are wetlands, rice fields, fossil fuels, livestock

9 Greenhouse Gases Nitrous oxides slow to breakdown Atmospheric lifetime = 120 years Provides 310 times more warming than CO 2 Sources are fossil fuels, fertilizers, deforestation CFCs absorb 10,000 X more infrared than CO 2 Atmospheric lifetime = Sources are foams, aerosols, refrigerants, solvents Water vapor Warmed by CO 2, the atmosphere is thus able to absorb more water vapor. And that water vapor, in turn, causes further warming it amplifies the effects of carbon dioxide.

10 Ice core analysis of air pollutants 60% of CH emission are a result of humans Human Activities Countries with the largest CO 2 emissions Per capita emissions of CO 2 Qatar is largest per capita: high gas production and low population Scientific and economic studies 2007: Field and Marland CO 2 will rise 3.3% a year Tipping point 2008: Aufhammer and Carson China s CO 2 emission growth may be underestimated

11 Atmospheric Levels of CO 2 and CH 4, Global Temperatures, and Sea Levels Carbon Dioxide Methane Temp. Sea Level

12 What natural and human-influenced factors could have an effect on temperature changes? Amplify (give positive feedback) Dampen (give negative feedback to) The Atmosphere Is Warming Mostly Because of Human Activities 1988-Intergovernmental Panel on Climate Change (IPCC) 90 99% likely that lower atmosphere is warming : Ave. temp increased about 0.74 C (1.3 F) : Annual greenhouse emissions up 70% Past 50 years: Arctic temp rising almost twice as fast as the rest of the earth Melting of glaciers and floating sea ice Prolonged droughts: increasing Last 100 years: sea levels rose cm 2007-Al Gore and the IPCC : Nobel Peace Prize the earth has a fever. And the fever is rising We are what is wrong, and we must make it right

13 Simplified Model of Some Major Processes That Interact to Determine Climate

14 Melting of Alaska s Muir Glacier between 1948 and 2004

15 Comparison of Measured Temperature from and Projected Changes

16 Is a Hotter Sun the Culprit? Energy output from the sun affects the earth s temperature. Since 1975 Lower atmosphere (Troposphere) has warmed Stratosphere has cooled This is not what a hotter sun would do!! Atmosphere is heating from the bottom up this indicates inputs at earth s surface (from human activities) are the main cause.

17 Can the Oceans Save Us? Solubility of CO 2 in ocean water But, solubility of gases decreases as temp. of water increase Help moderate temperature-remove 25-30% CO 2 Warmer oceans CO 2 levels increasing acidity Effect on atmospheric levels of CO 2 Effect on coral reefs - ability of to make shells, could dissolve shells Antarctica s Southern Ocean (largest CO 2 sink and the North Atlantic Ocean Decrease in CO 2 uptake Significance on global CO 2 levels Temperature, acidity, and the ability to absorb CO 2 from atmosphere are changing due to humans. This can accelerate global warming.

18 Uncertainty about the Effects of Cloud Cover on Global Warming Warmer temperatures increase evaporation and create more clouds Thick, light-colored low altitude clouds: decrease surface temperature Thin, cirrus clouds at high altitudes: increase surface temperature Effect of jet contrails on climate temperature trails expand and turn into large cirrus clouds that release heat into the upper troposphere

19 Outdoor Air Pollution Can Temporarily Slow Global Warming Aerosols (suspended microscopic droplets of solid particles) and soot pollutants Most light-colored sulfate particles produced by fossil fuel combustion tend to reflect incoming light- also serve as condensation nuclei and form clouds (more cooling) BUT black carbon particulate matter emitted by diesel exhaust, burning forest and cooking fuels warms the atmosphere more than estimated

20 Scientists do not expect aerosols or soot pollutants to enhance or counteract projected global warming 1. Fall back to the earth or are washed out of the lower atmosphere within weeks, where as CO 2 remains in the atmosphere for as long as 120 years! 2. Reduction: especially in developed countries Hmmm.. The decrease in some aerosols concentrations increase global warming!

21 Enhanced Global Warming Could Have Severe Consequences Why worry about it? How much and how fast Tipping point and irreversible climate change Worst-case scenarios Ecosystems collapsing Low-lying cities flooded Wildfires in forests Prolonged droughts: grasslands become dust bowls More destructive storms Glaciers shrinking; rivers drying up

22 Projected Effects of Global Warming and the Resulting Changes in Global Climate

23 19-2 Severe Drought Is Increasing: The Browning of the Earth Drought=evaporation exceeds precipitation Accelerate global warming, lead to more drought Biodiversity will decrease NPP will decrease Dry climate ecosystems will increase Positive feedback-accelerate global warming and climate change= more drought

24 Ice and Snow Are Melting Why will global warming be worse in the polar regions? Light colored ice and snow=reflect solar energy-cool earth Melting exposed dark land=absorb more solar energy=polar are heat up Important climate role of floating sea ice-precipitation Mountain glaciers affected by Average snowfall Average warm temperatures Europe s Alps Glaciers are disappearing South America Glaciers are disappearing Greenland Warmer temperatures

25 Sea Levels Are Rising 2007 IPPC-sea level will rise cm this century Expansion of warm water Melting of land-based ice What about Greenland? 1-2 meters from Projected irreversible effect Degradation and loss of 1/3 of coastal estuaries, wetlands, and coral reefs Disruption of coastal fisheries Flooding of Low-lying barrier islands and coastal areas Agricultural lowlands and deltas Contamination of freshwater aquifers Submergence of low-lying islands in the Pacific and Indian Oceans and the Caribbean

26 Areas of Florida to Flood If Average Sea Level Rises by One Meter

27 Should people be allowed to live in these flood prone areas if sea levels continue to rise? How can government discourage people from moving to coastal areas? How would the economies of coastal areas be affected by rising sea levels?