Factors That Affect Climate Change

Weather vs. Climate The pattern of temperature, wind, Climate-                                        The pattern of temperature, wind, precipitation, and other conditions within a region, averaged over a long period of time. Climate- The conditions of temperature, wind, precipitation, air pressure at any given moment. Weather- Which would you most likely look at when planning a winter vacation? planning a picnic?

Climate Change Climates on the earth have changed many times over billions of years. Between 20 to 100 thousand years ago, a good portion of North America was covered in a thick sheet of glacial ice. Recently, the Intergovernmental Panel on Climate Change (IPCC) has presented evidence that global climates are once again changing. (global warming intro videoclip)

Effects of the Earth and the Sun on Climate Solar energy (solar radiation) is the most important factor that affects climate The amount of solar radiation that reaches the earth varies in a mostly irregular fashion A sunspot cycle has been identified which occurs approximately every 11 years. Variations in sunspot activity have been linked to changes in global climate by some scientists.

The Earth in Space Because of the earth’s spherical shape, different latitudes receive different intensities due to the changing angles at which they strike the surface. { { The sun’s rays are less concentrated here The sun’s rays are most concentrated here Milankovic Cycles In the early 1900’s, the Serbian mathematician Milutin Milankovic showed that the amount and intensity of solar radiation received by the earth varies due to a series of three variables. Milankovic’s calculations support the idea that earth’s climate is expected to change over long periods of time.

The Earth in Space The seasons that we experience on earth are caused by a combination of the earth’s tilt on its axis, and its position in orbit around the sun. Earth’s axis of rotation is currently 23.44o. This angle is slowly decreasing over thousands of years. The intensity of solar radiation changes for different parts of the earth at different times during its orbital period.

The Earth in Space Other factors that result in changes in the intensity of solar radiation received by the earth are; Changes in the earth’s orbital eccentricity result in periods where the earth will be closer or farther from the sun. !

The Earth in Space Click picture for animation Not only does the earth tilt on its axis, but because it is not a perfect sphere, the earth wobbles as it spins about this axis. This wobble affects the solar energy received by the different hemispheres and leads to smaller or larger differences between the seasons in these two hemispheres.

The Albedo Effect land < water < ice The presence of ice and snow on the earth’s surface can have an effect on how much solar radiation gets reflected from the earth’s surface back out into space. albedo- a measure of the fraction (or amount) of solar radiation or light that is reflected by a surface. Lighter-coloured materials have a high albedo (reflect a lot of radiation) and darker-coloured materials have a low albedo (absorb more radiation than they reflect). Comparing albedo land < water < ice Videoclip “Arctic Changes

The Atmosphere The earth’s atmosphere is a mixture of gases (mostly nitrogen and oxygen and water vapour), extending from its surface up to an altitude of about 560 km. The atmosphere allows solar radiation to strike the earth’s surface, but then is able to absorb some thermal energy and reflect it back to earth before it can go out into space. This is called the greenhouse effect. Without the greenhouse effect, the average surface temperature on the earth would be about –20oC!

The Atmosphere Since gases are fluid, the particles are able to move past each other. Warmer, and therefore less dense, gas will rise above colder, more dense gas. This creates looping patterns of gas within the atmosphere. This, combined with the constant rotation of the earth creates prevailing wind patterns which we experience on the earth’s surface. Prevailing winds transfer thermal energy and moisture in a predictable way across the globe. They also help to create consistent movements in water called ocean currents.

The Hydrosphere The hydrosphere is made up of all of the water on the earth in all of its different forms.

The Hydrosphere Click here and scroll down to video on ocean currents The Earth’s Major Ocean Currents (link to laptop) Ocean currents can affect climate since they help to distribute thermal energy concentrated at the equator towards the poles. An overall circulatory pattern exists and is called the great ocean conveyor belt since it distributes thermal energy around the entire earth. The Great Ocean Conveyor Belt

The Hydrosphere Above colder water is colder and drier air. Cold ocean currents bring a drier climate to a coastal region. Above warmer water is warmer and humid (wetter) air. Warm ocean currents bring a more humid climate to a coastal region. How do ocean currents affect climate? CLICK HERE to find out! (click on “Keeping Current” link)

Moving Continents The outer surface of the earth consists of huge pieces of solid rock know as tectonic plates. These rock plates (about 12 major ones), move only a few centimetres each year, but this is enough to change the distribution of land and water across the surface of the earth over hundreds of thousands of years. When major plates collide, huge mountain ranges can form, creating changing patterns of wind and precipitation in that area.

Volcanic Activity The movement of tectonic plates also leads to the formation of active volcanoes. As a result of a volcanic eruption, huge amounts of ash, dust, and gases are spewed into the atmosphere as aerosols. The presence of these aerosols in the atmosphere can result in the reflection and scattering of more solar radiation from the earth, leading to less energy absorbed and cooler global temperatures. Some theories suggest that a large meteor which impacted the earth millions of years ago induced a similar but larger effect and eventually led to the demise of the dinosaurs.

Human Activities Since the Human Industrial Revolution which began in the late 1700’s, human beings have been developing and using technologies which have been linked to the changes in climate that are being experienced in current times. Climate changes that can be related to human activities are called anthropogenic factors. Anthropogenic climate change factors include: pollutants produced from the burning of fossil fuels depletion of forests, known as deforestation “greenhouse” gases to the atmosphere such as methane, nitrous oxide, and CFC’s from various industries (even H2O (water) is a greenhouse gas, but when it concentrates, it falls as rain)

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