652c47dadbb93b39868d21adff11a48f.ppt
- Количество слайдов: 35
Large Scale Human Impacts • As the human population is rapidly increases, humans are creating larger environmental changes. • Two major concerns are: – Ozone depletion – Global climate change
Ozone Layer • a layer of concentrated ozone gas made up of three oxygen molecules (O 3) between 20 and 50 kilometers above Earth’s surface absorbing harmful UV radiation UV-c = most harmful UV-b = main cause of most sun burns UV-a = least harmful
Ozone Depletion – Since the 1970’s scientists have been finding evidence that the ozone layer was thinning • Holes in the ozone layer were eventually found above both poles – Ozone holes caused by CFCs (chlorofluorocarbons) which break down ozone molecules
Ozone cont… Ozone Depletion • Destruction of the ozone layer has increased the ultraviolet radiation reaching Earth’s surface. • chlorofluorocarbons chemicals used in refrigeration (Freon) and aerosol cans, and in certain manufacturing processes protects from UV rays Loss of ozone above Arctic
Progression of atmospheric damage
Impacts • Ozone layer absorbs most of the harmful UV-B radiation • more UV-B means: – more melanoma and non-melanoma skin cancers – more eye cataracts – weakened immune systems – reduced plant yields – damage to ocean eco-ecosystems- kills producersphytoplankton – more damage to plastics
Effects of loss of Ozone Wrinkles & SKIN CANCER
Ozone Success • A phase out of cfc’s was enacted in 1987 • In 2000 the majority of governments banned the use of cfc’s • Ozone depletion has now slowed, and recovery is expected over the next 50 -100 years
Global Climate Change • As human consumption of fossil fuel has increased, so has our emissions of green house gasses • As these gasses have accumulated in our atmosphere, they have contributed to a change in the average temperature and climate on earth= global climate change
Climate Change • A 0. 5°C increase in the average temperature of the biosphere has occurred in the past 120 years (abiotic factor) – Natural variations do contribute to the variation in climate – However, human activities are adding carbon dioxide and other greenhouse gases into the atmosphere, making the atmosphere retain more heat • More carbon dioxide from burning fossil fuels, cutting down trees and burning forests
How it works… • Greenhouse Gasses trap and redirect infrared radiation back to the earth. This causes warming, like a car in the sun • The greenhouse effect is actually beneficialwithout it, earth would be too cold to support much life.
Different surfaces reflect different amount of light/radiation • What happens when the glaciers melt? ?
Most Important Greenhouse Gases GHGs: • Water: H 2 O • Carbon Dioxide: CO 2 • Methane: CH 4 PCC slide no. Source Examples: Oceans, Rivers, Plants, Soil Combustion, Respiration, deforestation + burning Wetlands, Oceans, Combustion, Animals (thawing permafrost) http: //www. for. gov. bc. ca Source: U. S. EPA 2005
Sources of anthropogenic greenhouse gases (2007) by gas by sector Source: U. S. EPA 2009
Methane By Source
U. S. 186. 1 Total CO 2 emissions European Union Between 1950 -2001 in billions of tons 127. 8 Russia 68. 4 Ukraine 21. 7 China Poland Canada 14. 4 14. 9 Kazakhstan 57. 6 10. 1 Japan 31. 2 India 15. 5 Mexico 7. 8 Kuwait Trinidad and Tobago Australia South Africa 8. 5 US: United Arab Emirat es 7. 6 4% of world’s total population 25% of the world’s greenhouse gases China: 25% of the world’s population TIME magazine, 2001 8. 5% of the world’s greenhouse gases (since 1950)
China emission
How cars generate CO 2 CH 2 + 1. 5 O 2 CO 2 + H 2 O 6. 3 lb/gal PCC slide no. 20 lb/gal Source: Murray 2005
Climate Change v. Climate Variability Climate change (e. g. warming trend) Climate variability (e. g. Natural swings) "climate" We see the sum of both Time (years)
More Evidence: Ice Cores • Ice layers preserve information about each year PCC slide no. Sources: NOAA, GISP 2 websites
Correlations
Scientific Consensus on Climate Change +35% • Carbon dioxide (CO 2) and other greenhouse gases warm the planet • Human activities have increased the concentration of the major greenhouse gases since 1750. • Average global temperature has increased 1. 3°F since 1906. Warming since the 1950 s very likely (>90% chance) due to human increases in GHG +142% +18% Figure source: IPCC
Future climate change PCC slide no. Source: IPCC 2007
Effects • It may result in rising sea level causing more frequent and more severe weather disturbances • Environmental changes benefit some species, but greatly disturb others that may not survive
Effects 1. Increase in the global temperature. 2. Melting of polar ice caps and glaciers. 1. Sea level rise- displaces people and habitats 3. Changes in the climate of certain areas of the world. 4. Increase in the number and severity of extreme weather events – – – hurricanes and tornadoes. Increased droughts in certain areas of the world Increased flooding worldwide 5. Decreased biodiversity in the coral reefs and rainforests. 6. May affect food production in key food producing nations.
Sea Level Rise • Melting of – Greenland Ice Sheet – Antarctic Ice Sheet – Glaciers and ice caps • Expansion of heated (warm) sea water 2 - 4 warming by ~2100 C 0. 18 - 0. 59 meter rise in sea level IPCC (2007)
Arctic Sea Ice (in September) 2007 2005 4. 3 5. 6 million km 2 sea ice edge (where normally found) data from National Snow and Ice Data Center (Boulder, CO, USA)
Loss of Sea Ice PCC slide no. Source: Arctic Council 2004
Could be a runaway process
Ecosystem services are provided, but it’s your responsibility to help save the Earth! Section 6 -4 Solar energy Production of oxygen Storage and recycling of nutrients Regulation of climate Purification of water and air Storage and distribution of fresh water Food production Nursery habits for wildlife Detoxification of human and industrial waste Natural pest and disease control Management of soil erosion and runoff Go to Section:
The Value of a Healthy Biosphere • What we have to remember: – A healthy biosphere provides us with many valuable goods and services (food, medicine, temperature control, water purification, soil formation, etc) • Make wise choices about resources used, disposal, recycling, and energy conservation