Long and Short Term Changes in Climate

By: Sarah Ramanathan Keiren AlamChantal 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. 

Introduction

• Long term changes:continental driftchanges 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.

Changes Due to Continental Drift

• 225 Million years ago: Pangaea (Permian period)

• 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 massNothern 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 changeThese changes have occurred in Canada because

we have new/old mountain regions (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 produced in volcanoes & mid-ocean trenches.Lost by slowly being absorbed into oceansAreas 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 overLand under oceans were exposed, revealing

hidden bridges to continentsAnimals crossed over to new habitats

• Major changes in temp happen in regular cycles

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 ageInterglacial 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 orbitEarth’s TiltDirection (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

In a cycle close to 42,000 years, Earth tilts back and forth on its axis from 22.1 degrees to 24.5 degrees

• 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

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 & Keiren

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.

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.

• 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

Ocean Currents

Ocean currents can have a major effect on the weather

The global conveyor belt begins around the North Pole and then works its way down, traveling through all of the

oceans before circling back

• 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: temperature changeImpuritiespressure

Air Currents

Thank You

Bibliography• Nelson Science Perspectives 10Nelson Education Ltd.2010Pages 348-353<http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/

climate.htm>.• Windows to the Universe2010 National Earth Science Teachers Association 200-2011http://www.windows2universe.org/earth/climate/cli_seasons.html • Woods Hole Oceanographic InstitutionShelley DawickiMarch 28, 2005http://www.whoi.edu/page.do?pid=9779&tid=282&cid=3638&ct=162• Long term climatehypertext G. H. Riekehttp://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/

climate.htm

• Pictures:• Long term climatehypertext G. H. Riekehttp://ircamera.as.arizona.edu/NatSci102/NatSi102/lectures/

climate.htmhttp://www.phy6.org/stargcc/Sconcat2.htmhttp://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 environmentWheeling Jesuit University/NASA-supported Classroom of the FutureSeptember 30, 2010http://www.cotf.edu/ete/modules/volcanoes/vclimate.html