Long term & short term effects of climatePresentation Transcript
Long Term & Short Term Effects of Climate Change By: Sarah Ramanathan Keiran Alam Chantal Liu Manal Rahim
For the past millions of years, our climate has had many significant changes. Changes in Earth's climate are triggered by changes in Earth's energy balance. Long term changes: - continental drift - changes in Earth's orbit Short term changes: - Volcanic eruptions - Air and Ocean Currents
Long Term Changes in climate(millions of years- hundreds of thousands of years) Chantal & Manal
Plate Tectonics = Theory of explaining slow movement of large plates of Earth's crust Continental Drift - Theory that Earth's continents used to be one supercontinent named Pangaea. 225 Million years ago: Pangaea (Permian period) Changes Due to Continental Drift
200 Million years ago: Laragia and Gondwanaland (Triassic period) 135 Million years ago: Jurassic period 65 Million years ago: Creations period.
Continents move = ocean currents and wind patterns change - Affects heat transfer Affects distribution of land mass - Nothern Hemisphere (includes Canada) has most land mass.
- Fewer large bodies of water = coldest winters & warmest summers - More large bodies of water in Southern hemisphere = more moderate climate - Temperatures weren't like this in Permian period
More mountains (caused by movement of Earth's plates) affects Local & regional climates Wearing of mountains over time can also cause regional climate change - These changes have occurred in Canada because we have new and old mountain regions such as the Rockies and Appalachians.
Scientists have found that over time the energy the Sun produces over time can also change Changes of area cause complications in production of CO2 - CO2 porduced in volcanoes & mid-ocean trenches. -> Lost by slowly being absorbed into oceans -> Areas w/ high overall temperature most likely had greenhouse warming due to volcanic CO2
Long-Term Cycles in Climate 20 000 years ago, Earth had last ice age. - Temp was 10 degrees lower than today - Canada covered in ice sheet 3 km thick - Sea levels dropped as oceans froze over -> Land under oceans were exposed, revealing hidden bridges to continents
-> Animals crossed over to new habitats Major changes in temp happen in regular cycles (page 349 of textbook) -warm interglacial periods occur every 100 000 years Interglacial Period - Time between ice ages when Earth warms up
Changes That Occur Over Hundreds Of Thousands Of Years: The Recurrence of Interglacial Periods and Ice Ages every 100,000 years, interglacial periods and ice ages occur Ice age (glacial period): long term reduction of Earth’s temperature = glaciers and ice sheets covering Earth
Interglacial periods: period of warmer temperature that separates periods of time in an ice age Interglacial periods involve movements of glaciers Causes temperatures to keep rising and falling depending on whether glaciers are advancing or retreating
Why these Interglacial Periods &Ice Ages Keep Happening? Engineer/astronomer Milutin Milankovitch developed theory on reason for these climate changes Earth’s orbit around sun changes on three main ways/cycles: Eccentricity (changing shape) of Earth’s orbit Earth’s Tilt Direction (wobble) of tilt
Eccentricity of the Earth’s orbit Shape of Earth’s orbit around sun changes Goes from almost circular to more elliptical (flattened circle/oval-like)
Caused by Jupiter and Saturn’s gravities Occurs approximately every 100,000 years Earth’s current cycle is more elliptical (oval-like)
Earth’s Tilt Earth’s current tilt = 23.5 degrees Earth’s tilt is responsible for its changes in seasons
Scientists believe that changes in Earth’s tilt are cause for glacial cycles occurring When Earth’s tilt is larger (closer to its 24.5 degrees max): Glaciations end Causes warmer summers Earth’s tilt currently decreasing
In a cycle close to 42,000 years, Earth tilts back and forth on its axis from 22.1 degrees to 24.5 degrees
Direction (wobble) of tilt (Axial Precession) In order to grasp the idea, think of a spinning top
As it spins, it wobbles around/changes direction while spinning on same point Earth’s tilt is similar As Earth’s spins on its axis, it slowly wobbles The angle of its tilt remains approximately the same but its directions changes Cycle of roughly 26,000 years
Short Term Changes in climate (decades-thousands of years) Sarah & Keiran
Volcanic Eruptions Volcanic eruptions can cause Earth’s climate to change temporarily rocks, dust, and gases are sent out high into atmosphere.
Suns energy reflects back out to space (from sulfur dioxide particles) Earth’s surface shaded. Amount of cooling depends on amount of dust put in air, and time of cooling-on size of particles.
Ocean Currents Uneven heating of Earth causes convection currents that create prevailing winds and ocean currents. Ocean currents have a strong effect on climates of nearby land Ocean currents can be caused by winds Cold ocean currents cool air above Warm ocean currents heat air above
The global conveyor belt begins around the North Pole and then works its way down, traveling through all of the oceans before circling back Ocean currents can have a major effect on the weather
Air Currents Air on Earth's surface is in constant motion called air currents Air currents affect air quality and ocean currents, and weather conditions Air currents caused by three main processes:
Changes in Sun’s Radiation suns radiation amount drops, Earth gets less energy (less heat =Earth cools down) suns radiation higher=more energy No scientific reason yet why radiation and over shorter time scales.
Bibliography Nelson Science Perspectives 10 Nelson Education Ltd. 2010 Pages 348-353 <http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/climate.htm>. Windows to the Universe 2010 National Earth Science Teachers Association 200-2011 http://www.windows2universe.org/earth/climate/cli_seasons.html Woods Hole Oceanographic Institution Shelley Dawicki March 28, 2005 http://www.whoi.edu/page.do?pid=9779&tid=282&cid=3638&ct=162 Long term climate hypertext G. H. Rieke http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/climate.htm
Pictures: Long term climate hypertext G. H. Rieke http://ircamera.as.arizona.edu/NatSci102/NatSi102/lectures/climate.htm http://www.phy6.org/stargcc/Sconcat2.htm http://room106vjh2.blogspot.com/2010_09_01_archive.html Black, Ken. "How does Ocean Temperature affect Air Temperature?" WiseGeek. Web. 10 Jan 2011. Capital Regional District. "Global Ocean Currents.". Web. 10 Jan 2011. Hayhoe, Christy, Douglas and Katharine. Energy Transfer within the Climate System: Air and Ocean Circulation. Perspectives 10. Canada: Nelson Eduacation Ltd, 2010. 344-348. Print. Exploring the environment Wheeling Jesuit University/NASA-supported Classroom of the Future September 30, 2010 http://www.cotf.edu/ete/modules/volcanoes/vclimate.html