Climate

1. Climate

2. Climate Vs. Weather • Weather • Day-to-day measure of the atmosphere in a region • Short term variations in: • Temperature • Cloudiness/Visibility • Precipitation • Humidity • Wind • Climate • Statistical weather information describing the variations in weather in a given region over a given time interval • Weather averages over 30 years

3. Global Climate • On a global scale, the climate of the Earth has varied significantly throughout the Earth’s history

4. Temperature averages over the last 2.4 Billion years. This graphic is not entirely to scale.

5. Major Causes of Climate Change • Energy from the Sun • Earth’s reflectivity • The greenhouse effect • Paleoclimatology • The scientific study of changes in climate over the entire history of the Earth.

6. Energy from the Sun • Insolation • Incoming Solar Radiation • Energy from the sun that reaches the Earth’s surface • Milankovitch Cycles • The position of the Earth in relation to the sun varies over different cycles that range from 26,000 to 413,000 years • Orbital Shape (Eccentricity) • Axis Tilt (Obliquity) • Axis Precession

7. Earth’s Reflectivity • In order for the Earth to maintain a constant temperature, the same amount of energy that is incoming from the sun must be reflected or radiated back into space • Albedo • Amount of reflectivity of an object • Snow is more reflective that asphalt • Plate tectonics affects reflectivity • Position of continents

8. The Greenhouse Effect • Without the Earth’s natural Greenhouse Effect, surface temperatures would be about 30 degrees Celsius colder

9. The Greenhouse Effect • The amount of Carbon Dioxide CO2 and other gases that trap radiation in our atmosphere varies naturally for many biological and geological reasons • Volcanic activity releases CO2 • Carbon Sinks • A reservoir that accumulates and stores Carbon • Forests • Oceans

11. Climate Feedback Loops • Feedback Loop • An initial process creates changes in a second process that in turn influences the initial process • Positive feedback loops lead to a great amount of change in a system • Negative feedback loops help to stabilize a system • Polar Ice Melting • As polar ice melts, less solar radiation is reflected and the ocean surrounding the remaining ice warms, creating further melting, creating further warming.

12. How do scientists determine ancient climates? • Ice cores • Tree rings • Rocks/Sediments • Corals/Shells • Fossils

13. Ice Cores • Scientists drill ice cores to study atmospheric makeup at different times • Air trapped within the snow is compressed into tiny air bubbles that can be studied • Current research have cores dating more than 800,000 years

14. Ice Cores • Ice deposition in glaciers is layered because of seasonal snowfall • The number of layers correlates with the number of years • Oxygen Isotope Ratios are used to determine average global temperatures

15. Tree Rings • Dendroclimatology • Scientists can study tree growth rings to determine past climates • Tree rings are wider when growth conditions are favorable, and narrower when growth conditions are poor

16. Tree Rings • Many trees are chosen from a given area to create a chronologic history of climate in that area • Trees must be dated • Count growth rings • Skeleton plotting • The oldest chronologic history created from tree rings is 11,000 years