Environment 10 Terms
Terms
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- albedo
- reflectivity; the fraction of radiation striking a surface that is reflected by that surface.
- greenhouse forcings
- An amount of heat trapped due to a given concentration of greenhouse gases, which can be calculated precisely.
- Natural climate variability can be due to:
- 1. Variation in Sunlight 2. Changes in geology and biology 3. Volcanoes 4. Shifts in Ocean Circulation
- Milankovitch cycles
- The cycles of the tilt and orbit of Earth. Has 3 aspects: eccentricity, obliquity, and precession.
- Eccentricity (Milankovitch Cycles)
- The shape of Earth\'s orbit around the sun, changing from more elliptical to more circular and then back again. Shift is every 100,000 years.
- Obliquity (Milankovitch Cycles)
- The angle of the Earth\'s tilt on its axis. Becomes less and greater, changes slowly and hits extremes every 41,000 years.
- Precession (Milankovitch Cycles)
- does the Northern or Southern Hemisphere face the sun when Earth is at its farthest point in annual revolution. (Southern summer or northern summer?). Changes every 19,000 to 23,000 years.
- Sun Spot Cycle
- An 11-year sunspot cycle on the sun that causes the sunlight amount to vary by ~0.1% over the cycle.
- Climate change in consideration to positive and negative feedback from Earth.
- Geologic records show that climate changes not smoothly but in sudden jumps, due to the balance of positive and negative feedbacks.
- Molecules that have a gas phase (carbon, nitrogen, and water) are cycled rapidly on Earth.
- Molecules that do not have a gas phase (calcium, phosphorus) cycle much more slowly.
- Precipitation patterns
- Increasing in: Southern South America, Western North America, Central North America, Eastern North America, Northern Europe, Northern Asia, and Central Asia. Decreasing in: Western Africa, Mediterranean Basin, Southern Africa, and Southern Asia.
- Sea level change rate
- currently rising about 3 mm/year.
- Sea level has already risen 8 inches from anthropogenic (human) influences.
- 70% of this is from thermal expansion; 30% of this is from glacial melting.
- Sea level rise of ~.5 m or more in this century
- If West Antarctic ice sheets break up, sea will rise 4-6 m. Ice sheet is on land that is below sea level.
- Species movement
- 80% of 1700 diverse species show movement poleward at an average rate of 61 km/century during the last century (forced by 0.6 C of warming), slightly above the rate of movement in the glacial record (10-45 km/century).
- Under thermal stress, colored zooxanthelae leave their coral hosts. Corals start to die within a couple of weeks.
- The first bleaching event in the past 18,000 years was in 1970. There have been 4 more since then. Each event kills 70-90% of the local reef.