Atmosphere & Climate Change

1. Atmosphere& Climate Change Section #3: Global Warming

2. sun’s energy streams into the car windows carpets & upholstery absorb the light energy & change it into heat energy heat energy cannot pass back out the windows as easily as light energy can heat gets trapped inside & continues to build up Greenhouse Effect

3. Earth is similar to a greenhouse atmosphere acts like the glass allowing sunlight to enter & heat the Earth’s surface heat radiates back from the Earth, some escapes into space, some is absorbed by gases in the troposphere - warming the air The Earth as a Greenhouse

4. the process of heat absorption is called the . . . GREENHOUSE EFFECT What do we call this process?

5. gases that absorb & radiate heat major greenhouse gases water vapor * carbon dioxide * chlorofluorocarbons methane nitrous oxide Greenhouse Gases

6. How the Greenhouse Works

7. geochemist Charles Keeling installed an instrument at the top of a tall tower on Mauna Loa in Hawaii in 1958 he could precisely measure CO2 in the air far away from forests & cities Measuring CO2 in the Atmosphere

8. in a forest, CO2 levels rise & fall with the daily rhythms of photosynthesis near cities, CO2 from traffic & industrial pollution raises the local concentration of the gas steady winds that have come thousands of miles over the Pacific Ocean blow over Mauna Loa, far from the affects of forests or cities Why did he need to get away from cities & forests?

9. Keeling believes that the air over Mauna Loa represents the average carbon dioxide levels for the entire Earth Keeling’s 1st measurement in 1958 was 314 parts per million over the next year, he noticed that the levels rose & fell with the seasons Carbon Dioxide Levels

10. summer levels = lower WHY? growing plants use more CO2 for photosynthesis than they release in respiration winter levels = higher WHY? dying grasses & fallen leaves decay & release the carbon that was stored in them Seasonal Changes

11. after a few years of measurements, Keeling noticed a change beyond the seasonal fluctuations each successive year, the carbon dioxide levels in the winter were higher than the previous year also each year, the summer levels did not fall as low Rising CO2 Levels

12. Graph Showing Overall Increase + Seasonal Fluctuations

13. the graph shows CO2 levels from 1958 to 2000 in those 42 years, carbon dioxide has gone from 314 ppm to 368 ppm, an increase of 54 ppm (or 17%) scientists hypothesize that this increase is due to the burning of fossil fules Where do we stand now?

14. scientists also think that because greenhouse gases trap heat near Earth’s surface, more greenhouse gases in the atmosphere will result in an increase in global temperatures supporting data for this view comes from a comparison of CO2 levels in the atmosphere & average global temperatures for the past 400,000 years Earth’s Temperature

15. power plants that burn coal or oil cars that burn gasoline the millions of trees that are burned to clear tropical rain forests for farming plus the release of other greenhouse gases Where is the CO2 Coming From?

16. Where Are the Gases Coming From?

17. a predicted increase in global temperatures resulting in a warmer Earth is referred to as global warming many scientists believe that the warming trend will continue throughout the 21st century How Certain is Global Warming?

18. Global Surface Temperatures

19. some scientists disagree that the warming trend is due to an increase in greenhouse gases these scientists believe that the warming is part of natural climatic variability pointing out that data reflects widespread fluctuations in temperature over geologic time How Certain is Global Warming?

20. unable to make accurate predictions climatic patters are complex & too many variables must be taken into account to be solved even using today’s fastest computers models have evolved quickly as more data is collected & analyzed, & as faster computers are built Modeling Global Warming

21. Variables to take into account when making predictions: carbon dioxide levels prevailing winds ocean circulation patterns temperature rainfall patterns sea level fluctuations cloud coverage amount of water vapor in atmosphere amount of ice changes in vegetation ocean chemistry Modeling Global Warming

22. Maps developed by computer models: the left shows the effect of greenhouse gases before sulfur pollution was added & the right one shows a cooling effect from the addition of sulfur pollution

23. Over the past thousands & even millions of years, Earth’s climate has changed dramatically scientists are not sure how quickly the Earth will warm or how severe the effects of global warming might be the impacts could set into play a number of serious environmental problems including disruption of global weather patterns global rise in sea levels adverse affects on human health, agriculture, plant & animal populations Consequences of a Warmer Earth

24. rising temps will cause a decrease in the amount of ice and snow at the poles melting would cause sea levels to rise leading to the flooding of coastal wetlands & other low-lying areas people living near coasts would loose their homes & businesses beaches could be eroded salinity in bays & estuaries could increase which could impact fish reproduction could flood fresh water aquifers near coasts Melting Ice – Rising Sea Levels

25. A 11,000 km2 iceberg that split from the Ross Ice Shelf in Antarctica in March 2000

26. as temps rise, the oceans will absorb more heat, leading to an increase in the # of hurricanes or typhoons could shut down or change ocean circulation patterns which would then impact the world’s weather this would lead to more rainfall in some areas (flooding) & less in other areas (droughts) Global Weather Patterns

27. increase in heat-related deaths – especially in the elderly & young who are more susceptible to heat exhaustion increases in ground-level ozone which could lead to higher temps that could impact those with respiratory illnesses increase in insects & the diseases they spread (note – malaria & encephalitis from mosquitoes) Human Health Problems

28. increases in temps might lead to droughts decrease in crop yields – not enough food for humans & other animals increase need for irrigation that might deplete freshwater stores (aquifers) Agriculture

29. Field of Drought

30. increases in temps might lead to changing the types of plants that can grow in an area which will impact the local food chain some areas will not have enough moisture to grow much of anything ocean food chains could be impacted by a decrease in plankton destruction of coral reefs Effect on Plants & Animals

31. IPCC (Intergovernmental Panel on Climate Change) – network of the world’s leading climatologists from 70 countries issued TAR (Third Assessment Report) in 2001 which describes the current knowledge about the global climate system & gives estimates of the future Recent Findings

32. the average global surface temperature increased by 0.6°C during the 20th century snow & ice coverage have decreased average global sea levels have risen concentrations of greenhouse gases have continued to increase Recent Findings

33. in 1997, reps from 160 countries around the world set timetables for reducing greenhouse gas emissions when 55% of the attending nations ratify this treaty called the Kyoto Protocol these timetables will go into effect Reducing the Risk

34. requires developed countries to decrease emissions of CO2 & other greenhouse gases by an average of 5% below their 1990 levels by the year 2012 the U.S. decided not to ratify the treaty in 2001 although most developed countries have Kyoto Protocol

35. recognizing the existence of global warming recognizing the human impacts reforestation projects to reduce CO2 reducing car exhaust emissions What We’re Doing Now:

36. Reforestation projects (like this one in Haiti) may help to offset a portion of CO2 emissions because plants take in CO2 during photosynthesis.

37. different countries are facing problems in the following factors and this is leading to conflicts between developed & developing countries economic factors political factors social factors Problems:

38. Developing countries are projected to make up half of all CO2 emissions by 2035