Studying Climate Change
Email this Mix
Slide 1 - Studying Climate Change
- Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Slide 2 - Studying climate change: Ice cores
- Ice caps and glaciers accumulated over thousands or millions of years.
- They contain bubbles of gas preserved from the time when each layer formed.
- Scientists drill cores and analyze the gas bubbles in each layer to see what the atmosphere was like then.
Slide 3 - Studying climate change: Pollen analysis
- Scientists also drill cores into the sediments of ancient lake beds.
- By identifying types of pollen grains in each layer, they can tell what types of plants were growing there at the time.
- Sources of this type of indirect evidence are proxy indicators.
Slide 4 - Studying climate change: Direct sampling
- Scientists have recorded carbon dioxide levels in the atmosphere directly since 1958, at a station in Hawaii.
- The data show a steady upward climb from 315 to 373 ppm.
- (The up and down zigzags are from regular winter-summer fluctuations.)
Slide 5 - Studying climate change: Modeling
- Computer simulations that use known behavior of past climate to analyze how climate should behave as variables are changed
- Coupled general circulation models (CGCMs) are models that combine, or couple, the effects of both atmosphere and ocean.
- To predict what will happen to climate in the future, scientists use climate models:
Slide 6 - Studying climate change: Modeling
- Today’s highly complex CGCMs incorporate many factors in order to predict future climate changes.
Slide 7 - Studying climate change: Modeling
- Natural or anthropogenic factors ONLY = poor fit.
- BOTH types of factors = excellent fit.
Slide 8 - Climate change and the IPCC report
- In 2001, the world’s climate scientists combined to produce the single most comprehensive and authoritative research summary on climate change:
- The Third Assessment Report of the
- Intergovernmental Panel on Climate Change (IPCC),
- which summarized all scientific data on climate change, future predictions, and possible impacts.
Slide 9 - Climate change and the IPCC report
- First, the IPCC report established that global temperature is rising.
- Direct measurements from thermometers since 1860 demonstrate this.
Slide 10 - Climate change and the IPCC report
- Proxy indicators of temperature (from pollen, ice cores, etc.) were reviewed to establish ancient temperatures.
- These data (BLUE) overlapped with the direct temperature measurements (RED). (Gray shows statistical uncertainty.)
Slide 11 - The IPCC report
- The IPCC also reported findings on physical changes:
- • Average sea level increased 10–20 centimeters (4–8 inches) during 20th century.
- • 2 weeks less ice cover on northern lakes and rivers.
- • Arctic sea ice thinned 10–40% in recent decades.
- • Mountain glaciers melted back worldwide.
- • Snow cover decreased 10% since satellite observations began.
- • Growing season lengthened 1–4 days each decade over the past 40 years.
Slide 12 - The IPCC report
- Biological changes were also found by the IPCC:
- • Geographic ranges of many species have shifted toward the poles and up in elevation.
- • In spring, plants are flowering earlier, birds migrating earlier, animals breeding earlier, and insects emerging earlier.
- • Coral reefs are “bleaching” more frequently.
Slide 13 - Sea-level rise
- Global warming is causing glaciers to shrink and polar ice shelves to break away and melt.
- The increased flow of water into the oceans lead to sea level rise.
- Sea level is also rising because ocean water is warming, causing water to expand in volume.
- Higher sea levels lead to beach erosion, coastal flooding, intrusion of saltwater into aquifers, etc.
Slide 14 - Sea-level rise
- Storm surge = temporary and localized rise in sea level caused by high tides and winds associated with storms
- Storm surges impact small islands as well as low-lying coastal areas in countries like the U.S.
- This vulnerability became dramatically apparent in 2005 when Hurricane Katrina struck New Orleans and the Gulf Coast of the U.S.
Slide 15 - Sea-level rise
- A 51-centimeters (20-inches) sea level rise would inundate wetlands (red) and drylands (orange) on all U.S. coasts.
Slide 16 - Sea-level rise
- Areas on all U.S. coasts would suffer erosion.
- Dramatic flooding from storm
- events like Hurricane Katrina
- could become more frequent.
Slide 17 - Climate change predictions: Impacts
- The IPCC and other groups have predicted future impacts of climate change. Predictions for the U.S. include:
- • Temperature will rise 3–5°C (5–9°F).
- • Droughts, floods, snowpack decline, and water shortages will create diverse problems.
- • Temperature extremes will cause health problems; tropical diseases will move north into the U.S.
- • Sea level rise will flood coastal wetlands, real estate.
- • Ecosystems will be altered; some will disappear.
- • Agriculture and forestry may have mixed results.
Slide 18 - Predicted U.S. impacts
- The Canadian model (a) predicts Illinois to be warmer and drier in the future. The Hadley model (b) predicts a warmer and moister climate.
Slide 19 - Predicted U.S. impacts: Forest types change
- Distribution of forest types will change
- 2 future scenarios
Slide 20 - Predicted U.S. impacts: Heat index rises
- Two models show big increases in July heat index for the next 100 years, especially in the central and southeast U.S.
- (Heat index combines temperature and humidity.)
Slide 21 - Predicted U.S. impacts: Mortality
- Deaths from summer heat waves will increase.
Slide 22 - Emissions reduction: More efficient generation and usage
- Electricity generation is the biggest source of greenhouse gas emissions in the U.S.
- So solutions include:
- • Improved technology at plants
- • Cleaner-burning coal
- • Energy conservation by consumers
Slide 23 - Emissions reduction: Renewable energy
- Another solution is to switch to renewable energy sources:
- Hydroelectric power
- Geothermal energy
- Photovoltaic cells
- Wind power
Slide 24 - Emissions reduction: So many cars
- Transportation: the 2nd largest source of greenhouse gases.
- 1/3 of average U.S. city devoted to cars
- Average U.S. family makes:
- 10 car trips/day
- $200 million/day on road construction and repair
- Number of cars in U.S. will soon exceed number of people
Slide 25 - Emissions reduction: Inefficient autos
- Cars use energy very inefficiently. We could do better.
Slide 26 - Emissions reductions: Biking and walking
- Reducing automobile usage would also lower emissions.
- More and more people are choosing to live closer in and bike or walk to work.
- If Americans used public transportation at the rate Europeans do, the U.S. would no longer need Saudi Arabian oil.
Slide 27 - Emissions reductions: Public transportation
- Using public transportation like buses and trains lowers emissions of many pollutants … which has a public health benefit as well.
Slide 28 - Emissions Reductions: International Treaties
- 1992: UN Framework Convention on Climate Change
- Voluntary approach; nations were asked to cut emissions
- 1997: Kyoto Protocol drafted
- By 2012, reduce 6 greenhouse gases to below 1990 levels
Slide 29 - Emissions Reductions: Kyoto Protocol
- Reductions required under Kyoto are scaled to nations’ contributions.
- Germany decreased emissions 18.9% while its economy grew strongly.
Slide 30 - Emissions Reductions: Kyoto Protocol
- The Kyoto Protocol has been ratified by 127 nations, enough to make it binding.
- The U.S. continues to refuse to ratify the treaty.
Slide 31 - Emissions reductions: Kyoto Protocol
- Supporters and opponents of Kyoto agree, however, that the treaty alone is not enough to turn around greenhouse gas production worldwide—it would just slow it down.
- Developing nations say industrialized nations like the U.S. created the problem, so they should be the ones to take the lead in cleaning it up.
- The U.S. administration has said the treaty is unfair because it does not force developing nations like India and China to share in the burden of reducing emissions.
Slide 32 - Conclusion
- Many factors shape global climate.
- Scientists and policymakers are beginning to understand anthropogenic climate change and its impacts more fully.
- Many scientists and policymakers are deeply concerned.
- As time passes, fewer experts are arguing that the changes will be minor.
- Sea-level rise will affect developed and developing countries alike.