Lesson Video: Global Warming | Nagwa Lesson Video: Global Warming | Nagwa

Lesson Video: Global Warming Science

In this video, we will learn how to explain the rise in temperature of Earth’s atmosphere and the potential problems.

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Video Transcript

In this video, we will learn how to explain the rise in temperature of the Earth’s atmosphere and the potential problems.

We often hear that climate change is happening on the Earth. But what does this mean? Climate change is a change in the Earth’s climate caused by human activity that alters the composition of the global atmosphere in addition to natural climate variability. The layer of gases that surrounds the Earth is known as the atmosphere. These gases are essential to sustaining life on our planet. The four main gases in Earth’s atmosphere are nitrogen, oxygen, carbon dioxide, and water vapor. Nitrogen and oxygen make up most of the atmosphere. In the troposphere, which is the part of the atmosphere closest to Earth’s surface, the gases are mixed together uniformly to make the air we breathe.

So, what does it mean to alter the composition of the global atmosphere? Altering the composition means we are changing the relative amounts of gases or adding new gases to the atmosphere that would not normally be there. The main change that humans have made to the atmosphere that is causing climate change is increasing the amount of greenhouse gases.

Having more greenhouse gases in our atmosphere has altered Earth’s natural climate variability. If something is variable, this means it is changing or fluctuating. Climate in areas of the world does change naturally over time. Climate includes, for example, the average temperature or rainfall. But climate change refers to a change of Earth’s natural climate patterns due to human activity. In other words, human activity is disrupting the Earth’s normal climate patterns and leading to extreme weather events.

People often confuse climate change with global warming, but they are not the same thing. Global warming is the long-term increase in Earth’s average global temperature. Scientists can calculate the average temperature near the surface of the Earth by measuring it at many locations around the planet. The graph shows an example of how the average global temperature increases and decreases by a small amount over time. In other words, in a short period of time, the average global temperature naturally goes up and down by a small amount.

Scientists describe global warming as a long-term change. What does this mean? On the second graph, the 𝑦-axis represents the mean or average global temperature, just like the first graph. But the 𝑥-axis represents a much longer period of time. It shows the time in years from 1880 to 2020, which is 140 years. Between 1880 and 2012, the average global air temperature increased by 0.85 or almost one degree Celsius. This is a much larger change than the small changes that happen naturally.

Scientists predict that global temperature will continue to increase by almost three degrees Celsius by 2100. Between the 18th and early 20th centuries, the industrial revolutions happened. Since then, the average global temperature has continually increased. This rise is due mainly to the burning of fossil fuels by humans, which is increasing the amount of greenhouse gases in Earth’s atmosphere.

So, what exactly are greenhouse gases? Greenhouse gases are gases found in the atmosphere, both naturally and through human activity, that absorb and emit IR radiation emitted by the Earth’s surface, the atmosphere itself, and clouds. We already know that Earth’s atmosphere is made up of the following gases. Of these gases, only carbon dioxide and water vapor are greenhouse gases. Other common greenhouse gases include methane, nitrogen oxides, ozone, and chlorofluorocarbons, which have the abbreviation CFCs. Let’s discuss each of these in more detail.

Water vapor is the gaseous form of water. Of all the greenhouse gases in the atmosphere, water vapor is found in the greatest amount. During the water cycle, water evaporates from bodies of water like oceans and lakes. Water also moves into the atmosphere from plant leaves during a process called transpiration.

Now, let’s discuss carbon dioxide. Carbon dioxide, or CO2, gets into Earth’s atmosphere by both natural processes and human activity. One way CO2 enters the atmosphere is through the respiration of organisms on Earth. Volcanic eruptions and forest fires also release CO2 into the atmosphere. But over the last century, the amount of carbon dioxide in the atmosphere has increased mostly because of the combustion of fossil fuels by humans. Finally, deforestation also leads to higher CO2 levels.

The combustion or burning of a fossil fuel is a chemical process that produces carbon dioxide directly. Gasoline is combusted to run a car. And many people around the globe get electricity from the burning of coal in power plants. Deforestation also leads to higher CO2 levels. During photosynthesis in the leaves of trees, carbon dioxide and water are used to make glucose and oxygen. If there are fewer trees on the Earth, then fewer CO2 molecules can be removed from the atmosphere.

Methane is another greenhouse gas that enters Earth’s atmosphere by both natural and human causes. The decomposition of food waste in landfills increases the amount of methane in the atmosphere. Livestock also produce methane during their digestion of food and as their manure decomposes.

Nitrogen oxides are greenhouse gases that are composed of the elements nitrogen and oxygen. The formula NO𝑥 is used for nitrogen oxides because the gases can have different numbers of nitrogen and oxygen atoms. For example, common nitrogen oxides are nitrogen monoxide, or NO, and nitrogen dioxide, or NO2. Using fertilizers, manufacturing nitric acid, and burning fossil fuels and biomass all increase the amount of nitrogen oxides in the atmosphere. Nitrogen oxides also cause the depletion of the ozone layer.

Two other important greenhouse gases are ozone, or O3, and chlorofluorocarbons. Ozone in the ozone layer is helpful because it protects life on Earth from harmful UV radiation. But when ozone is produced in the troposphere, it is harmful to human health. Finally, chlorofluorocarbons are very strong greenhouse gases, and they also cause the breakdown of the ozone layer.

The greenhouse gas produced most by humans is carbon dioxide. Two-thirds of all greenhouse gases produced by humans is the CO2 made from the burning of fossil fuels. Another 11 percent is the carbon dioxide that is rising because of how humans use land. This includes deforestation. Methane, nitrous oxide, CFCs, and other gases make up only about 25 percent of the greenhouse gases produced by humans.

Now, let’s discuss how greenhouse gases contribute to global warming. Greenhouse gases contribute to the greenhouse effect. When direct sunlight shines through the glass of a greenhouse, the air inside the greenhouse heats up. The greenhouse effect is the process through which gases in the Earth’s troposphere trap the Sun’s heat in the form of IR radiation. We know greenhouse gases absorb and emit IR radiation emitted by the Earth’s surface, atmosphere, and clouds. Let’s go through this process step by step.

Visible light and shortwave ultraviolet, or UV, radiation from the Sun move through the atmosphere. Some of this radiation is reflected back into space by the atmosphere. If the radiation makes it through the atmosphere, some of it is also reflected by Earth’s surface. Shortwave UV light is absorbed by the ozone layer in the stratosphere. And some UV and visible light are absorbed by Earth’s surface. Some of the radiation that is absorbed by the Earth is emitted as infrared, or IR, radiation. Most of this IR radiation is absorbed by greenhouse gases. The energy is then released from the gas molecules as thermal energy. So, the IR radiation remains trapped in the troposphere and warms the Earth.

Earth’s atmosphere is essential for sustaining life. The Earth must be warm enough, but not too hot. Too many greenhouse gases leads to global warming. But if we removed all the greenhouse gases from the atmosphere, the global temperature would be too cold.

Let’s summarize some of the main ideas. Greater amounts of greenhouse gases cause an increase in the greenhouse effect. This leads to global warming. As the global temperature rises, climate change happens.

So, what is being done to help slow down global warming and climate change? Many scientists around the world are studying global warming and climate change to understand it better and come up with ways to stop it. The Intergovernmental Panel on Climate Change, or IPCC, is a part of the United Nations that keeps track of and evaluates this research.

Climate change affects different parts of the Earth in different ways. In some areas, there are changes in rain and snow patterns, droughts, or heat waves. In other areas, flooding, wildfires, or hurricanes may become more frequent or severe. Because of rising global temperatures, glacier ice, sea ice, and continental sheet ice is melting. Habitat for animals such as polar bears and seals is being destroyed because of this melting. The melting ice has led to rising sea levels. This is causing more flooding in coastal areas and more loss of habitat.

In 2015, the Paris Agreement began so that countries could work together to combat global warming and climate change. One of the main goals of the agreement is to reduce greenhouse gas emissions. Carbon dioxide makes up most of the greenhouse gas emissions. And we know most of it comes from burning fossil fuels. So, if we burn less fossil fuels, we may be able to slow down global warming and climate change.

One way to do this is to drive cars less. We can walk, bike, or use public transportation instead. Another way to reduce CO2 emissions is to use less electricity. A lot of electricity comes from the burning of fossil fuels, such as coal. To use less electrical energy, we can turn off lights when they are not needed and turn off and unplug computers, televisions, and appliances when we are not using them. If possible, we should use energy-efficient appliances and light bulbs.

Before we summarize all that we’ve learned, let’s take a look at a question.

What term do scientists give to the fact that the average temperature near to the surface of the Earth has steadily risen over the past 100 years? (A) Scorched Earth, (B) climate change, (C) global warming, (D) ozone depletion, (E) the greenhouse effect.

First of all, the rise in the average global temperature over the past 100 years is due to increasing concentrations of greenhouse gases in the atmosphere. Having more greenhouse gases in the atmosphere amplifies a process called the greenhouse effect. In the greenhouse effect, greenhouse gases in the Earth’s troposphere trap the Sun’s heat in the form of IR radiation.

Over the last 100 years, the concentration of greenhouse gases, such as CO2, have increased mainly from the burning of fossil fuels. When radiation from the Sun enters the atmosphere of Earth, some of the radiation is reflected back to space. Some of the radiation is absorbed by the Earth and emitted in the form of IR radiation. Carbon dioxide and other greenhouse gas molecules absorb the IR radiation that is emitted by the Earth and release it as thermal energy. This thermal energy increases the global temperature slowly over time. So, we can say that global warming is the long-term increase in the Earth’s average global temperature.

It’s important to remember that the average global temperature naturally increases and decreases by small amounts over time. However, the term global warming refers to the increase in global temperature that is caused by human activity. This increase in Earth’s temperature over time has changed the climate of the planet.

The terms global warming and climate change are often confused. The increase in average global temperature is called global warming. Climate change refers to how the climate in regions of the world changes because of global warming. Climate change involves changes to the weather patterns, such as rainfall and snow. Weather events like flooding, droughts, and heat waves may also become more frequent or severe.

In conclusion, the term scientists give to the fact that the average temperature near to the surface of Earth has steadily risen over the past 100 years is answer choice (C), global warming.

Now we’re ready to summarize our learning with some key points. Climate change is caused by human activity, which has changed the composition of Earth’s atmosphere and its natural climate patterns. Global warming is the long-term increase in the Earth’s average global temperature that is causing climate change. Some of the effects of global warming are the melting of Earth’s ice, loss of habitat, and rising sea levels. Climate change involves worsening weather patterns, such as droughts, heat waves, hurricanes, and floods.

The greenhouse effect happens because greenhouse gases in Earth’s troposphere absorb IR, or infrared, radiation emitted by the Earth’s surface. These gases then release the energy as thermal energy, which warms the Earth. Common greenhouse gases are water vapor, carbon dioxide, methane, nitrogen oxides, ozone, and chlorofluorocarbons. Carbon dioxide makes up almost two-thirds of the greenhouse gases produced by humans and comes mainly from the burning of fossil fuels.

The Intergovernmental Panel on Climate Change, or IPCC, evaluates research on climate change and helps countries combat climate change. An individual can help reduce global warming by driving a car less and reducing the amount of electricity used at home.

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