Climate Change Is climate change new Climate change

Climate Change

Is climate change new? Climate change is a natural part of Earth’s history. For example, thousands of years ago, thick ice sheets covered most of Canada and a large portion of the United States.

Factors Affecting Climate Change 1. The Sun 2. Earth’s Orbit 3. The Atmosphere 4. The Hydrosphere 5. Moving Continents 6. Human Activity

Factors Affecting Climate Change 1. The Sun 2. Earth’s Orbit 3. The Atmosphere 4. The Hydrosphere 5. Moving Continents 6. Human Activity

Climate Change and Solar Energy The most important factor that affects the climate on Earth is the Sun. • Solar energy travels through space as light, or electromagnetic radiation • The intensity of the energy that reaches Earth’s surface affects the temperature of air, water and land on the planet. • Heat produces winds, rain and other features of climate. • The amount of solar energy that reaches Earth depends on solar activity, the shape of the Earth and the tilt of the Earth (Next Factor).

Climate Change and Solar Energy � Changes in Solar Activity cause variations in the amount of energy from the sun to the earth � For example the 11 year sunspot cycle effects how much radiation the sun emits. When the number of sunspots is high, the Sun emits higher amounts of solar radiation. � There is some belief that changes in solar output are the main causes of climate change in the past.

Factors Affecting Climate Change 1. The Sun 2. Earth’s Orbit 3. The Atmosphere 4. The Hydrosphere 5. Moving Continents 6. Human Activity

How Earth’s Orientation Affects Climate 1. Rotation 2. Revolution 3. Tilt 4. Wobble 5. Latitude

Rotation vs. Revolution & Tilt Movements of Earth in Space �Earth rotates once every 24 hours around its axis, an imaginary line that goes from the North Pole to the South Pole through the center of the Earth. �The Earth also revolves (orbits) around the Sun over a 365 day period (1 year). �Another important detail is that the Earth’s axis of rotation is tilted at an angle of about 23. 5 o perpendicular to the orbital plane. http: //www. physicalgeography. n et/fundamentals/6 h. html

Earth’s Seasons The seasons are created by Earth’s revolution and its tilted axis. Flashlight Demo

Earths Orbital Eccentricity: The Shape of Earth’s Orbit • Earth’s orbit fluctuates due to the gravitational attraction of other planets in the solar system. • Its path around the Sun changes very slowly from elliptical to more circular over a 100 000 year period due to the gravitational effects of other planets in the solar system. • Elliptical orbit – planet receives more solar radiation when near the Sun than it does when it is farthest from the Sun • Circular orbit – amount of solar radiation varies less throughout the year • This slightly affects the intensity of the Seasons, however, does not explain recent climate changes

Earth’s Tilt and Climate Precession: How the tilt of the Earth’s axis changes slightly over time. • Earth is not a perfect sphere (slightly oblate). It wobbles slightly as it rotates on its axis. This is called precession (Top demo) • The wobble affects the intensity of solar energy that is received by the northern and southern hemispheres at different times of the year. This causes the changes in temperature between the seasons. • The greater the tilt the greater the differences in temperature between summer and winter.

Effect of Latitude on Climate and Seasons � � The sun’s rays are most intense at the equator, where they hit the Earth perpendicular to its surface. As the Sun’s position in the sky lowers the sunlight received decreases. At a latitude of 45 o south, the Sun’s rays strike the Earth’s surface at an angle and as a result the rays are spread over a larger area. The Earth here receives less solar energy because it is more spread out. At the poles, the Sun’s rays are spread out over an even larger area, and therefore the energy from the sun is divided into even smaller amounts per unit area See Flashlight Demo

Factors Affecting Climate Change 1. The Sun 2. Earth’s Orbit 3. The Atmosphere 4. The Hydrosphere 5. Moving Continents 6. Human Activity

Atmospheric Factors that Affect Climate 1. Greenhouse Effect 2. Wind

The Atmosphere & Climate Recall…The atmosphere starts at Earth’s surface and goes up to about 560 km into space. It is mostly made of nitrogen (N 2) and oxygen (O 2) gases as well as water vapour, very low concentrations of other gases and particles.

The Atmosphere & Climate: Energy from the sun entering the atmosphere -The amount of energy that reaches the Earth from the Sun, is called the solar constant, and is 1367 J/m 2/s. -What this means is that every square metre on Earths surface receives 1367 J of energy every second (average comparable to energy in shooting a gun every second) • However, not all incoming radiation (energy) is absorbed

How does the absorbed energy affect the climate? The Greenhouse Effect Absorbed Radiates Radiation Earth’s Surface Thermal energy Atmosphere Thermal Energy The greenhouse effect is a natural process that keeps Earth’s temperatures within a certain range. Without it the Earth would be colder (34 o. C lower) and most of the solar energy reaching Earth would radiate out back into space.

The Greenhouse Effect The greenhouse effect is the natural warming caused when gases in Earth’s atmosphere absorb thermal energy that is radiated by the Sun and Earth. The atmosphere contains greenhouse gases which absorb some radiation and transmit the rest. The solar radiation warms the surface of the Earth and heat rises from the surface to warm the air. Some heat is able to pass back through the gases and some cannot. The heat that is trapped adds to overall global temperatures.

Winds and Energy � Wind is the movement of air from an area of high pressure to an area of lower pressure. The air moves as wind transfers thermal energy around the world from warm areas to cooler areas. � Wind is caused by uneven heating of Earth’s surface which causes pressure variations in the atmosphere � The • • movement of air affects: Ocean currents Precipitation patterns Wind moves energy from warm areas cool areas As a result of air moving from high pressure low pressure *** Winds disperse energy through the atmosphere.

Winds and Ocean Currents -Winds transfer kinetic energy to the surface of the oceans and cause the water to move in surface ocean currents. -Since oceans absorb energy from the Sun, the movement of water transfers heat around the Earth’s surface. -The red arrows indicate warm surface currents -The blue arrows indicate cold surface currents

Prevailing Winds blow in fairly constant directions around the world. These large scale wind patterns are known as prevailing winds.

Winds Affect Precipitation � � � As air masses of different densities move across the Earth’s surface, they interact. When air masses meet (called a front), one air mass usually rises over the other. The rising air cools and any water vapor in the air condenses to form precipitation.

Winds – Jet Streams • Winds also affect precipitation through jet streams. Jet streams are high-altitude winds that travel long distances at very high speeds. • These winds may carry warm, moist air, which can produce precipitation in areas from the origin of the jet stream. • They may also carry dry, cool air, which causes dry weather in areas affected by the jet stream. • Canada’s weather is mostly influenced by the polar jet stream.

Factors Affecting Climate Change 1. The Sun 2. Earth’s Orbit 3. The Atmosphere 4. The Hydrosphere 5. Moving Continents 6. Human Activity

How the Hydrosphere Affects Climate The hydrosphere includes all of the water on the planet in its different forms. With the atmosphere, water transfers heat from one part of the planet to another. Water is found in many forms: • vapour and clouds of water droplets in the atmosphere • ice and snow in temperate and colder regions

How the Hydrosphere Affects Climate � Oceans and lakes act as heat reservoirs. They buffer temperatures in the atmosphere. (i. e. Lake effect) • The oceans can hold a lot more heat than the atmosphere can. The top 2. 3 metres of the oceans hold as much heat as all of the air on the planet. • Large bodies of water influence climate because water has a large specific heat capacity compared with other substances.

Specific Heat Capacity � Specific heat capacity is the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius. • Water has a large specific heat capacity. This means it takes more heat to raise the temperature of 1 g of water by 1 o. C than it does to do the same to many other substances. • The higher the heat capacity, the longer it takes to warm the substance up, and the slower the substance loses its heat. • Water’s high specific heat capacity means that a land mass near a large body of water will have its temperature “moderated” by the water – it will warm up more slowly in summer and cool down slowly in winter than will a land mass further from water. Temperature Result: • Large bodies of water’s temperatures change slowly and by small amounts • Land masses temperatures change more quickly and by large amounts

Specific Heat Capacity Some Common Specific Heat Capacity Values Substance Specific Heat Capacity in Pure Water 4. 18 Sea Water 3. 89 Dry Air 1. 00 Wet mud 2. 51 Sandy soil 0. 92 “The number of joules of heat energy needed to raise the temperature of 1 g of the substance by 1 o. C. ”

Ice and Snow Reflect Heat � The light colour and reflective nature of ice and snow allow solar radiation to be reflected instead of absorbed The amount of energy (light) that is reflected by a surface is known as albedo. The percent of incoming radiation that is reflected is the Albedo. • Light-coloured surfaces reflect energy (light) – High Albedo • dark surfaces absorb energy (light) – Low Albedo • Because of their large differences in albedo, the distribution of water, ice and land on Earth’s surface greatly affects the average global temperature.

Factors Affecting Climate Change 1. The Sun 2. Earth’s Orbit 3. The Atmosphere 4. The Hydrosphere 5. Moving Continents 6. Human Activity

How Moving Continents Affect Climate � Earth’s outer layer is made of massive pieces of solid rock, called tectonic plates. Earth has about 12 major plates that move at a rate of a few centimeters per year. • The plates carry the continents with them as they move. This means that the shape of the oceans and continents is always changing. • Patterns of air and water circulation are affected which in turn affects thermal energy around the world. The formation of mountain chains also affects the patterns of wind and precipitation around the globe.

Uplift and Weathering • Upthrusting mountain ranges expose minerals to weathering. • Weathering is the breaking down of Earth's rocks, soils and minerals through direct contact with the planet's atmosphere • The exposed minerals change chemically into carbonates. This process removes carbon dioxide from the atmosphere and cools the Earth.

Volcanic Eruptions � Most volcanoes are located at the boundaries of tectonic plates � Plate movement affects climate by producing volcanic activity � In these areas, molten rock and gases from below the Earth’s crust rise up through cracks in the rock and spew into the air as volcanic eruptions.

Volcanic Eruptions • Particles called aerosols (such as ash) are released into the atmosphere. • Aerosols reflect solar radiation preventing it from entering the atmosphere resulting in a cooling effect on the global climate • This effect may last from a few years several decades • In contrast, some volcanic eruptions can raise global temperatures by releasing greenhouse gases.

Factors Affecting Climate Change 1. The Sun 2. The Earth 3. The Atmosphere 4. The Hydrosphere 5. Moving Continents 6. Human Activity

How Human Activity Affects Climate • Many human technologies burn fossil fuels (coal, oil and natural gas). • Since the late 1700 s they have been affecting our atmosphere, • During the Industrial Revolution, many new machines requiring fossil fuel power were invented. Examples of technologies that use fossil fuels: • trains • automobiles • ships • factories • aircraft • farming • mining equipment • home furnaces • electricity generating stations When fossil fuels are burned to release energy, they release gases and other pollutants into the atmosphere as waste products. Many of these gases affect the natural processes that produce the greenhouse effect.

Burning of Fossil Fuels… tmrw

Classwork � Complete….