Climate Change & Humans

1. Climate Change & Humans Chapter 12

2. Are Climates Changing? • Many observed climate records only go back 150 years so we have to rely on indirect evidence such as: • Ice cores • Size of tree rings • Composition of coral • Lake sediments

4. What’s the concern for? • The rate of climate change in the last 50 years and the amount of greenhouse gases. • Remember: some areas may be cooling while others, the warming may be much greater. It’s important that we look at the average.

5. Avg. temperature has increased by 0.6 °C in the last century • BUT this rate of increase has not occurred in the last 10 000 years!

6. Enhanced Greenhouse Effect • Results from GHG’s that are added to the atmosphere mostly by human activity. • Water vapour takes up about 65% of the natural GHE and it can have positive and negative feedback • Positive:  warming causes  water vapor which loops back and temp. • Negative:  vapor causes  clouds which reflects sunlight which has a cooling effect. • Makes it hard to predict what will happen…

7. Warming Potential of GHGs GHGs differ in several ways including: their global warming potential (how well they absorb infrared compared to CO2) the time they remain in the atmosphere the rate of increase since 1850

8. Global warming potential of GHGs Depends on: amount of gas entering the atmosphere each year lifetime in the atmosphere effects on the atmospheric chemistry effect on other gases

9. Carbon Dioxide and Carbon CO2 is the most abundant GHG that contributes to enhanced GH effect produced by burning fossil fuels, burning forests and when soil is cultivated has increased by 31% and concentrations have not been as high as it is now in the last 420 000 years.

10. Carbon Cycle Carbon naturally cycles through the biosphere Next to the hydrologic cycle, it has the largest annual exchange of matter.

12. Carbon Sinks a major source or reservoir of carbon compounds, can be both.

13. Methane Also known as Natural gas, produced by bacterial decay of organic matter. Also released from rice paddies, wetlands, landfill sites and cows. Used to heat homes and generate electricity. Has a warming potential 21X that of carbon dioxide and contributes to 20% of the enhanced GH effect. Concentrations have increased by 146% since the 1800s.

14. Methane hydrate Unique structure of methane combined with water. Forms under specific temp and pressure and these deposits are primarily in deep oceans. Discovered only a few decades ago! Scientists believe that deposits contain twice the amount of conventional natural gas

15. Nitrous Oxide Has a warming potential 300X that of carbon dioxide contributes to 6% of the enhanced GH effect released when fossil fuels and wood are burned at very high temperatures and when nitrogen-containing fertilizers are used.

16. Halocarbons or HCFCs Carbon compounds that contain halogens, like chlorine CFC’s were developed in the 1930s as coolants and propellants in aerosols. causes thinning of the ozone layer! Has been banned in most countries

17. OZONE- ground level only creates photochemical smog by oxides of nitrogen and vapours of gasoline, solvents, and oil-based paints react in heat and sunlight. Causes increased cases of asthma and other lung conditions

18. Changes to Canadian Biomes Most of Canada is currently tundra and taiga but with rising CO2 levels and other factors (changes in precipitation), scientists are expecting to see deciduous, and grasslands to increase and even some desert!

19. Some specific effects of climate change... changes to amounts and patterns of precipitation changes in salinity and ocean currents rising sea levels could put costal towns at risk human health could be affected by pollution and clean drinking water changes in composition and dominance of species

20. Intergovernmental Panel on Climate Change (IPCC) Formed in 1988 by the United Nationals Environmental Program and the World Meterological Organization Largest gathering of scientists to work on the issue The Third Assessment Report in 2001 projects a global temp rise of 1.4 to 5.8°C by 2100

21. Kyoto Protocol Agreement created in 1997 in Kyoto, Japan to reduce GHG emissions Over 160 countries signed (USA opted out in 2001) If targets not meet by 2012, it must make up the difference plus a 30% penalty Criticism: Businesses will suffer, a reduction of 50% in GHG is needed to advert climate change

22. Human ResponseIn a group of 2, quickly prepare a “Cole’s notes” of each of the following topics to present to the class today: • Adapting to Climate Change p.459 • Long-term Adaptation p.459 • Reducing the amount of climate change p.460 • Storing carbon dioxide p.460 • Reducing GHG emissions p.461-462 • Renewable energy sources p.462 • Relating Climate Change to scientific Inquiry p.463 • Societal Decision Making and Climate Change p.463 • What are the Choices? p.465 • The Precautionary Principle p.465

23. The Gaia Hypothesis Dr. James Lovelock, a NASA scientist, developed the Gaia hypothesis in the 60’s “The entire range of living matter on Earth from whales to viruses and from oaks to algae could be regarded as constituting a single living entity caple of maintaining Earth’s atmosphere to suit its overall needs and endowed with faculties and powers far beyond those of its constituent parts.” The Earth as a single organism