1. Chapter 4: Ecosystems & Communities Starting with … Climate (4.1)

2. THINK ABOUT IT When you think about climate, you might think of dramatic headlines: “Hurricane Katrina floods New Orleans!” or “Drought parches the Southeast!” But big storms and seasonal droughts are better described as weather rather than climate. What is climate, and how does it differ from weather? How do climate and weather affect organisms and ecosystems?

4. Weather and Climate Weather: day-to-day condition of Earth’s atmosphere Climate: average conditions over long periods defined by year-after-year patterns of temperature and precipitation Climate is rarely uniform even within a region Environmental conditions can vary over small distances: microclimates Ex: Northern Hemisphere, south-facing sides of trees and buildings receive more sunlight, often warmer and drier, than north-facing sides These differences can be very important to many organisms.

5. What factors determine Global Climate? 3 main influences 1. Greenhouse Effect & Solar Energy 2. Solar Energy & Latitude 3. Heat transport

6. 1-Solar Energy & the Greenhouse Effect Solar Energy main force that shapes our climate arrives as sunlight that strikes Earth’s surface

7. Where does the energy go from there?: reflected back into space absorbed and converted into heat… Heat also radiates back into space trapped in the biosphere. Earth’s avg temp = Heat that stays – Heat that is lost 1-Solar Energy & the Greenhouse Effect

8. Earth’s temperature is controlled by concentrations of 3 greenhouse gases carbon dioxide methane water vapor Function like glass in a greenhouse, allowing visible light to enter but trapping heat the greenhouse effect 1-Solar Energy & the Greenhouse Effect

9. GH gas conc.  trap more heat  Earth warms GH gas conc.  more heat escapes  Earth cools Without greenhouse effect  Earth would be about 30°C cooler than it is today 1-Solar Energy & the Greenhouse Effect

10. Animation http://www.youtube.com/watch?v=DuiQvPLWziQ

11. Uneven heating of Earth’s surface causes predictable variation in climate. Why? Radiation is more intense near the equator compared to the poles -it’s warmer near the equator than at the poles North Pole Earth Equator South Pole 2-Latitude & Solar Energy

12. Uneven heating of Earth’s surface causes atmospheric circulation Greater heating at equator than poles 1. sun’s rays hit more directly 2. less atmosphere to penetrate Therefore 1. Net gain of energy at equator 2. Net loss of energy at poles 2-Latitude & Solar Energy

13. What about seasons? Why do we have them? Earth’s distance from the sun varies throughout the year – doesn’t that cause the seasons? Tilt! Tilt of Earth’s axis  the amount of radiation received by Northern and Southern Hemispheres to vary seasonally Northern Hem. has summer when it tilts toward the sun, winter when it tilts away Southern Hem. has summer when it tilts toward the sun, winter when it tilts away

14. North Pole Earth When the north pole tilts toward the sun, it gets more radiation – more warmth during the summer SUMMER (Northern Hemisphere) South Pole WINTER (Southern Hemisphere) When the north pole tilts toward the sun, the south pole tilts away So when it’s summer in the north, it’s winter in the south Equator 2-Latitude & Solar Energy

15. When the north pole tilts away from the sun, it gets less radiation – So it’s colder during the winter North Pole Earth WINTER (Northern Hemisphere) South Pole SUMMER (Southern Hemisphere) When the north pole tilts away from the sun, the south pole tilts toward it… When it’s winter in the north, it’s summer in the south Equator 2-Latitude & Solar Energy

16. 3-Heat Transport in the Biosphere Unequal distribution of heat across the globe creates wind and ocean currents transport heat and moisture Earth has winds because warm air is less dense and rises, and cool air is more dense and sinks

17. Intense radiation at the equator warms the air Warm air rises, collecting moisture Air cools as it rises, moisture condenses and falls as rain Lots of rain in the tropics!

18. some of the rising air flows south some of the rising air flows north Rising air is now dry… Dry air descends at around 30º N …and at around 30º S Deserts The descending air flows N and S

19. Climate of any region is predictable from topography, wind and ocean currents >32ºC 29-32 ºC 27-29 ºC 24-27 ºC 21-24 ºC 18-21 ºC 16-18 ºC 13-16 ºC Arizona’s July temperature

20. Lesson Overview Lesson OverviewClimate 3-Heat Transport in the Biosphere Air that is heated by warm areas of Earth’s surface— such as near the equator— rises, expands, and spreads north and south, losing heat along the way. As the warm air cools, it sinks.

21. Lesson Overview Lesson OverviewClimate 3-Heat Transport in the Biosphere In cooler regions, near the poles, chilled air sinks toward Earth’s surface, pushing air at the surface outward. This air warms as it travels over the surface and rises.

22. Lesson Overview Lesson OverviewClimate 3-Heat Transport in the Biosphere These upward and downward movements of air create winds. Winds transport heat from regions of rising warmer air to regions of sinking cooler air. Earth’s rotation causes winds to blow generally from west to east over the temperate zones and from east to west over the tropics and the poles.

23. Lesson Overview Lesson OverviewClimate 3-Heat Transport in the Biosphere Similar patterns of heating and cooling occur in the oceans. Surface water is pushed by winds. Ocean currents, like air currents, transport enormous amounts of heat.

24. Lesson Overview Lesson OverviewClimate Heat Transport in the Biosphere Warm surface currents add moisture and heat to air that passes over them. Cool surface currents cool air that passes over them. In this way, surface currents affect the weather and climate of nearby landmasses.

25. Lesson Overview Lesson OverviewClimate Heat Transport in the Biosphere Deep ocean currents are caused by cold water near the poles sinking and flowing along the ocean floor. This water rises in warmer regions through a process called upwelling.

26. Ocean currents move 40% of “excess heat” from equator to poles Driven by circulation of deep ocean waters Deepwater formation occurs near Greenland and in Antarctic 60% of heat transport is carried by atmosphere through storms that move along pressure gradients

27. Earth’s climate is now warmer than at any time in the last 1000 years 1. increased solar input (small warming effect) 2. Increased sulfate aerosols reflects radiation (small cooling effect) 3. Increased greenhouse gas concentrations (large warming effect) 4. Land-cover change creates a darker surface (large warming effect)

28. Changes in solar orbit causes long-term variations in solar input to Earth Angle of tilt Wobble of tilt Shape of orbit

29. Most major greenhouse gases are increasing in atmospheric concentrations

30. Climate is warming most rapidly at high latitudes This warming is most pronounced in Siberia and western North America

31. Functioning of ecosystems varies predictably with climate

35. Climate gives rise to predictable types of ecosystems

36. Distribution of ecosystems is predictable from global patterns of wind and ocean circulation