1. Earth's Climate
1.1. The Earth’s climate system is a result of interactions among its components. Scientists, economists and politicians are discussing climate and climate change in order to prepare for our future needs.
1.2. Definition of weather: Refers specifically to the environmental conditions that occur at a particular place at a particular time.
1.3. Definition of climate: The average weather conditions that occur in a region over a long period of time.
1.4. How weather affects our life: Weather influences our choice of clothing and location. It makes us more cautious about where we are during a lightning storm for example.
1.5. The four main factors that affect the climate of an area: latitude, elevation, the air masses that flow over the area, and the area’s near ness to large bodies of water.
1.6. How climate affects our life: Different climates in different parts of the world, it determines the needs of humans, producing food differs depending on weather throughout the year, clothing depends on climate, etc.
1.7. The climate of a region is not only affected by the amount of solar radiation it receives, but also by the interactions among the components of the Earth’s biosphere. The biosphere is a thin layer of Earth that supports life, and is unique to planet Earth.
1.8. Both weather and climate depend on the amount of energy received rom our Sun. one of this energy is reflected, and some is absorbed by the Earth. This determines how much the earth might heat up and how the winds blow and currents flow - and drives many of the biosphere’s interactions.
1.9. The greenhouse effect is a natural process and is essential to life on Earth. Essentially, the atmosphere around the Earth acts like a “greenhouse” for the Earth. The atmosphere - made up of water vapour, carbon dioxide, and methane as well as other materials - acts like the glass on Earth. Without the atmosphere, this thermal energy would escape into space and Earth would be much cooler.
1.10. The definition of insolation: The amount of solar radiation received by a region of Earth’s surface.
1.11. The definition of net radiation budget: The difference between the amount of incoming radiation and the amount of outgoing radiation.
1.12. Why is it important that some of the insolation hitting Earth returns to space?
1.12.1. If some of the insolation hitting Earth didn't return to space, Earth would just get hotter and hotter. Earth would become an uninhabitable planet.
1.13. n diagram 7.18 on p. 277 of your textbook (Net Radiation Budget) what is the difference between the yellow parts of the diagram and the the brown parts of the diagram. (Be specific about what kind of radiation it is).
1.13.1. The yellow parts of the diagram shows incoming solar radiation and the brown parts of the diagram show how the atmosphere emits the outgoing infrared radiation.
1.14. What is the annual average of solar radiation (in Watts/square meter - W/m^2) hitting the outer surface of Earth’s atmosphere?
1.14.1. 342 W/m^2
1.15. In W/m^2, how much of this radiation, reflects back into space?
1.15.1. 107 W/m^2
1.16. In W/m^2, how much of this radiation, is absorbed by the atmosphere?
1.16.1. 67 W/m^2
1.17. What is the annual average outgoing infrared radiation?
1.17.1. The annual outgoing infrared radiation is 235 W?m^2.
1.18. In a complex system this energy is reflected, absorbed, transformed and released into the atmosphere. It is also this thermal or heat energy that drives the climate on the Earth. In general, thermal energy transfer is the movement of thermal energy (heat) from an area of high temperature to an area of low temperature to an area of low temperature. This energy transfer can occur by radiation, conduction or convection.
1.19. The definition of radiation: The emission of energy as waves
1.20. The definition of conduction: The transfer of thermal energy through direct contact between the particles of a substance, without moving the particles to a new location
1.21. The definition of convection: The transfer of thermal energy through the movement of particles from one location to another.
1.22. Almost all of our climate can be derived form the patterns of circulation on Earth. And circulation can be traced back to the transfer of energy across the biosphere. Circulation patterns are caused by the movement of heat energy from high temperatures to low temperatures and these give rise to the weather and climate patterns across the Earth - wind, ocean currents, annual rain fall and temperatures across regions.
1.23. When thermal energy is transferred in the atmosphere winds are created.
1.24. The creation of wind
1.24.1. Earth as a whole receives insolation from the Sun, but different parts of Earth receive different amounts
1.24.2. As the heated atmospheric gases gain energy and expand, the air becomes less dense and rises
1.24.3. Atmospheric pressure is the pressure exerted by the mass of air above any point on Earth’s surface
1.24.4. The rising and sinking masses of air in convection currents cause changes in atmospheric pressure, which cause wind.
1.25. If Earth were not spinning, there would be a continuous convection current between the polar and the equatorial regions.
1.26. Changes in the jet streams affect the formation of severe weather events such as squalls, storms, and cyclones, it also helps predict weather changes.
1.27. Ocean circulations transport roughly the same amount of energy towards the poles as does the atmosphere. They are the main pathways for the transfer of thermal energy from the warmer latitudes near the equator to cooler areas near the poles. There are two types of ocean currents.
1.27.1. Surface Currents: The surface ocean currents are driven by the global wind patterns. The winds push on the surface of the water to a depth of about 100 m. Since they are caused by the winds, the surface currents reflect Earth’s global wind patterns.
1.27.2. Deep Ocean Currents: This current known as the global ocean conveyor belt is a “constantly moving system of deep-ocean circulation driven by temperature and salinity. The great ocean conveyor moves water around the globe. This motion is due to thermohaline currents (thermo = temperature; haline = salinity). Cold, salty water is dense and sinks to the bottom of the ocean while warm water is less dense and rises to the surface.
1.28. Both types of current affect Earth’s climate. For example, “ocean surface currents redistribute heat around the world and have a profound effect on the world’s climate. Nowhere is this clearer than in the North Atlantic Ocean. The Gulf Stream and the North Atlantic Current ferry huge volumes of warm salty tropical water north to the Greenland coast and to the Nordic Seas. Heat radiating off of this water helps keep the countries of northwest Europe, which are at the same latitude as Labrador and Greenland, relatively comfortable places to live”.
1.29. Precipitation: Since the amount of precipitation of an area is very important important to climate, the hydrologic cycle is an important factor in Earth’s climate. Deserts for instance are in areas where precipitation is very low. This occurs either in areas where the air cannot hold too much water - like in the arctic - or in areas where the prevailing winds do no carry the moisture over the land.
1.29.1. Precipitation will be severely affected as the Earth’s temperature continues to rise. More water will fall in areas already experiencing significant rainfall, and areas that are already dry will experience increased drought.
1.30. Large Bodies of Water - We live in a city that is close to a large body of water. This actually puts Toronto into a microclimate and we often have very different weather from places that are not located near Lake Ontario. Large bodies of water, like oceans and seas, as well as very large lakes can have a dramatic effect on the climate of the area.
2. Evidence of Climate Change
2.1. Carbon Dioxide and other Greenhouse Gases: Certain greenhouse gases in our atmosphere are necessary to keep it warm. They are the greenhouse gases and contribute to the greenhouse effect. Scientists monitor these gases, especially, CO2 levels, in our atmosphere as indicators for climate change. They do so now through ice core data.
2.2. Global Surface and Water Temperature: As temperature is a measure of the amount of heat and energy trapped on Earth, and heat is a driver of many of the climate systems on the planet, scientists continue to monitor global temperatures as an indicator of Earth’s changing climate. CO2 levels and global temperature are closely linked.
2.3. Arctic Sea Ice: Sea ice essentially covers the Arctic Ocean during the winter months, but also recedes during the summer months when the hours of sunlight in the Arctic are much longer. In around mid-September the ice reaches its minimum thickness and covers only about half the area it does in the winter. Scientists have used the measurement of sea ice melt as an indicator of climate changes because warmer air and water temperatures “are reducing the amount of sea ice present”. If the amount of ice recedes significantly, it can play a significant role in the Earth’s energy balance. “As the amount of sea ice decreases, the arctic region’s ability to stabilize the Earth’s climate is reduced”.
2.4. Land Ice/Glaciers: As with sea ice, snow and ice on land are an “important part of the global climate system. Because snow and ice are highly reflective, much of the sunlight that hits these surfaces is reflected back into space instead of warming the Earth. The presence or absence of snow and ice affects heating and cooling over the Earth’s surface, again influencing the planet’s energy balance”.
2.5. Sea Level: Sea levels are intricately linked to all the indicators above. As the CO2 levels rise, and global temperatures rise, snow and ice begin to melt. As a consequence sea levels rise, and global temperatures rise. Furthermore, rising temperatures cause the water to expand - slightly However, if the water is expanding of the entire depth of the oceans, this can have a large effect on sea levels.
2.6. The Intergovernmental Panel on Climate Change (IPCC) 4 Key Findings
2.6.1. 1 - There is 95 percent certainty that human activities are responsible for global warming
2.6.2. 2 - Carbon dioxide is at an “unprecedented” level not seen for at least the last 800,000 years
2.6.3. 3 - Sea level is set to continue to rise at a faster rate than over the past 40 years
2.6.4. 4 - Over the last two decades, the Greenland and Antarctica ice sheets have been melting and glaciers have receded in most parts of the world.