Long Term and Short Term Changes in Climate; The Albedo Effect

Long Term Climate Change The Cause and Effects

What and How? Long term climate change occurs over million of years. There are many causes to L.T.C. changes, such as changes in earth’s orbit, shifting of continents, and cycle of climate change

Continental Drift The movement of continents. Climate Change Continental Drift The movement of continents. A long time ago, there was a single continent. Over millions of years, the continent “broke apart” to form present day Earth.

Climate Change Continental Drift Movement of land affects the climate in different ways. Changes in ocean currents, wind patterns and land mass. The result: heat transfer is affected.

Continental Drift. The Animation.

Cycles Not every type of climate change is permanent. Some occur in cycles. Changes in Earths orbit also causes changes in climate and it occurs in cycles.

Changes in Orbit Specific term: Eccentricity Causes of long term climate change Changes in Orbit Specific term: Eccentricity The Earth’s orbit around the sun changes shape. It changes after around 100 000 years. The reason: Jupiter and Saturn’s gravitational pull.

Causes of long term climate change Changes in Orbit When the orbit changes, Earths distance from the sun is either consistent or varied. When the distance is consistent, the seasons are mild. When The distance is varied, the climate tends to be more “extreme”.

Causes of long term climate change Changes in Orbit Change in orbit is a slow transition from almost circular to elliptical. The change is very slow! Right now earths orbit is elliptical.

Tilt The earth slowly tilts back and forth on its axis. Causes of long term climate change Tilt The earth slowly tilts back and forth on its axis. The earth tilts around 22.1º to 24.5º. Happens over 41000 years. Currently, earth is tilted 23.5º. This angle is decreasing.

Climate Change Tilt As the tilt increases, the so does the difference in temperature of seasons. The Earth also “wobbles” around its axis.

Short Term Climate Change

Short Term Factors Volcanic eruptions Changes in the Sun’s radiation Changes in air currents Changes in ocean currents

Volcanic Eruptions Rocks, dust and gases are released into the atmosphere The sulfur dioxide particles which are released reflect the Sun’s energy back to space Since there is less energy, the Earth cools down temporarily

Volcanic Eruptions Example on pg. 351 (Fig. 7)

Air and Ocean Currents Changes in thermohaline circulation can cause changes in climate Thermohaline circulation is the flow of water around the world’s oceans driven by differences in temperature and salinity There are some changes which occur regularly, an example is El Nino

Ocean Currents

(cont.) Ocean currents affect climate Example: The air above warm ocean currents is heated. The land is warmed and rain is produced when this warm, moist air reaches land. This is why air and ocean currents can affect climate

El Nino Occurs every 3 to 7 years Prevailing winds temporarily change direction Ocean currents change Warm water is pushed towards S. America Because of this, the west coast of S. America gets warm, wet weather

El Nino On pg. 353 (Fig. 8) in textbook

The Sun’s Radiation The amount of radiation the earth receives affects climate Small changes can affect the climate of the earth When the amount of radiation is lower, there is less energy, the climate cools If radiation increases, there is more energy, the climate warms

The Albedo Effect

Feedback Loops Small changes can have large effects This is because the small changes can be made bigger because of feedback loops A positive feedback loop increases the original cause A negative feedback loop decreases the original cause

Water Vapour and Feedback Loops An example of positive feedback loops is the water vapour in the atmosphere More water vapour forms since if the climate warms. Water vapour is a greenhouse gas and traps radiation. This further warms up the earth. It is the same when the climate cools. Less water vapour is formed and the climate cools even more

Albedo This is the radiation which is reflected by a surface Different surfaces have different albedos, an example would be ice which reflects much of the sun’s radiation The albedo of a planet is a measure of how much radiation is reflected back when the sun shines on it Earth has an albedo of 0.30-0.40

Albedo Diagram

Albedo Effect This is an important feedback loop in Earth’s climate It is a positive feedback loop Relationship between ice on surface of the Earth and the avg. temperature If the temperature increases, ice melts and less radiation is reflected which further increases the temperature If it decreases, ice forms and more radiation is reflected

The Albedo Effect

Questions What are the long term changes affecting the earth? What is continental drift? What can the movement of large land masses cause? Does the orbit of the earth change? How? What are the short term changes which can affect climate? How do volcanic eruptions cause changes in climate?

Questions (cont.) What is albedo? What is the albedo effect? What happens if the temperature of the planet increases? What happens if the teperature of the planet decreases?