Climate

1. Climate The average yearly conditions of temperature and precipitation in a region

2. Think about it… • Why do the leaves of plants change color and fall in the autumn? • What is hibernation and why do some animals engage in it? What types of animals, generally, hibernate?

3. Weather and Climate • Weather is the daily condition of Earth’s atmosphere at a particular place and time. • Climate is the average yearly conditions of temperature and precipitation in a region. • Climate is caused by: • Trapping of heat in the atmosphere • Latitude • Transport of heat by winds and ocean currents • Amount of precipitation • Shape and elevation of landmasses

4. The Greenhouse Effect • The greenhouse gases are atmospheric gases that trap infrared radiation (heat energy) that has been reflected off the Earth’s surface thus maintaining Earth’s temperature range. • The natural event in which heat is retained by this layer of greenhouse gases is called the greenhouse effect. Sunlight Some heat escapes into space Greenhouse gases trap some heat Greenhouse gases trap some heat Atmosphere Earth’s Surface

5. The Greenhouse Effect • Could we survive without the greenhouse effect? • No, Earth would be too cold for many organisms to survive, including human beings. • Can you name any greenhouse gases? • Think about cycles of matter… • Water Vapor – evaporation (water cycle) • Carbon Dioxide (CO2) – burning fossil fuels, deforestation, volcanic eruptions • Methane (CH4) – decomposition/decay, livestock waste • Nitrous Oxide (N2O) – fertilizer, fossil fuels, denitrification • Synthetic gases (e.g. CFCs) – industrial processes

6. Latitude • Earth is a sphere tilted on it axis. • Therefore, solar radiation strikes different parts of Earth at an angle that varies throughout the year. This leads to the seasons we have here. • The equator receives nearly direct sunlight all year. • The polar regions receive sunlight at a lower angle. • The three main climate regions of the earth are: • Tropical • Temperate • Polar

7. Earth’s Main Climate Zones 90°N North Pole Polar Sunlight 66.5°N Arctic Circle Temperate Sunlight Tropic of Cancer 23.5°N Equator Tropical Most direct sunlight 0° Tropic of Capricorn 23.5°S Sunlight Temperate Antarctic Circle 66.5°S Sunlight Polar 90°S South Pole

8. Heat Transfer in Biosphere • Unequal heating of Earth’s surface drives winds and ocean currents, which transport heat throughout the biosphere. • Warm air over the equator rises, while cooler air over the poles sinks toward the ground. • The upward and downward movement of air creates air currents, or winds, that move heat throughout the atmosphere.

9. Earth’s Winds WINDS Polar Easterlies 66.5°N Westerlies 23.5°N Northeast Trade Winds 0° Equator Southeast Trade Winds 23.5°S Westerlies Polar 66.5°S Easterlies Prevailingwinds

10. Heat Transport in the Biosphere • Similar patterns of heating and cooling occur in Earth’s oceans. Cold water near the poles sinks, then flows parallel to the ocean bottom, and rises in warmer regions. • Water is also moved at the surface by winds. • Movement of the water creates ocean currents, which transport heat energy throughout the biosphere. • Surface ocean currents warm or cool the air above them, affecting the weather and climate of nearby landmasses.

11. Ocean Currents OCEAN CURRENTS 66.5°N 23.5°N Equator 0° 23.5°S 66.5°S Warm currents Cold currents

12. Atmospheric Carbon Dioxide • Remember from our last class that carbon dioxide is released from a variety of sources. A major contributor to atmospheric CO2 is human activity. • Levels of CO2 in the atmosphere have risen dramatically sense the advent of the industrial revolution. • Why do you think this is the case? • In 1850, just before the industrial revolution the [CO2] in the atmosphere is estimated at about 274 ppm. • In 2005, the [CO2] in the atmosphere was over 370 ppm, an increase of over 25%.

13. Atmospheric Carbon Dioxide • What do you think are some potential effects of increased CO2 in the atmosphere?

14. Atmospheric Carbon Dioxide • Some potential effects of increased [CO2] could be: • Increased growth/productivity by vegetation (increased levels of photosynthesis). Why? (Hint: last class) • C3 plants (rice, wheat, soybeans) are more limited by CO2 availability than C4 plants (sugarcane, corn) so C3 plants may spread into C4 areas. • A link between increased CO2 and increased temperature exists. So when [CO2] rises, temperature rises. Why? (Hint: this class) • What are some potential results, globally and locally, from rising temperatures?

16. Holocene Extinction • The Holocene Extinction is the present, widespread, ongoing extinction during the current Holocene Epoch. • This is the Sixth Great Extinction, the largest since the one that killed off the last of the terrestrial dinosaurs. • The Holocene Extinction has been going on since about 11,000 BCE and has been attributed to anthropogenic causes by a majority of biologists. • Human-induced climate change, overexploitation, deforestation, and the introduction of non-native species may have all played a role.

17. Importance of Diversity • Because all species are interdependent upon one another, what is the potential impact of losing any one species? • The brazil nut, the tree from which the name of the edible nut is derived, is one of the most massive and important trees in the Amazon. • Only one creature, a rodent called the Agouti, can crack the shell, thus allowing the tree to reproduce. • Video: http://www.arkive.org/brazil-nut-tree/bertholletia-excelsa/video-11.html • Video: http://www.youtube.com/watch?v=HURyGlOksR0

18. Interdependence • There are literally thousands of examples of species’ interdependence. • Many flowers have evolved to be dependent upon insects for pollination. • Can you think of an example? • The Holocene Extinction is generally thought to have begun with the extinction of the megafauna at the end of the last Ice Age. • Many of these species were hunted to extinction, while others lost their sources of food due to human overexploitation.

19. Megafauna • The Wooly mammoth (Mammuthusprimigenius) • The theory of its extinction is controversial. • Most scientists believe it was due to climate change, overhunting, or a combination of the two.

20. Megafauna • The Saber-toothed Cat (Smilodonpopulator) • Extinction causes thought to be similar to mammoth’s. • Likely due to overhunting by humans.

21. Recent Extinctions • Baiji (Lipotesvexillifer) • Freshwater river dolphin from China • ‘Effectively Extinct’ 2006 • Caused by humans: pollution in rivers, habitat destruction (dams), fishing, collisions with boats.

22. Recent Extinctions • Javan Tiger (Pantheratigrissondaica) • Subspecies of tiger on Indonesian island of Java. • Extinct in 1980s due to hunting and habitat destruction.

23. Holocene Extinction • If trends continue, what species will most likely survive? Why? • If trends continue, what species will most likely go extinct? Why? • How is this related to global climate change?

24. Bell Ringer • 1. The Earth’s polar regions remain cold because • A. they are never heated by the sun. • B. the sun’s rays are at a very low angle at the poles. • C. the greenhouse effect does not occur at the poles. • D. heat is transported from the poles to the equator. • 2. Earth’s temperature range is maintained by • A. ocean currents and wind. • B. latitude differences. • C. the greenhouse effect. • D. climate zones. • 3. The Holocene Extinction • A. is when the dinosaurs died. • B. led to the Cambrian Explosion. • C. resulted from photosynthesis evolution. • D. is occurring right now.