Our world is always changing. Look out your window long enough and you might see weather change.

Look even longer and you'll see the seasons change. The earths climate is changing too, but in ways that you can't easily see.

 

The earth is getting warmer because people are adding the heattrapping gases in our atmosphere, mainly by burning fossil fuels. 

The gases are called green house gases. Warmer temperatures are causing other changes around the world, such as melting glaciers and strong storms. These changes are happening because the eath's air, water and land are all linked to the climate. The earth's climate has changed before, but this time is different. People are causing these changes, which are bigger and happening faster than any climate changes that modern society had ever seen before.

 

Climate refers to the average weather conditions in a certain place over many years. Climate in one area is called regional climate and the average climate around the world is called global climate. When scientists talk about global warming, they are talking about the global climate an a pattern of change that is happening over many years. One of the most important trends that scientists look at, is average temperature of the earth, which had been increasing for many years. This is called global warming. 

 

Rising global temperatures lead to other changes around the world, such as strong hurricanes, melting glaciers and the loss of wildlife habitats. That is because the earth's air, water and land are all related to one another and to the climate. This means a change in one place can lead to other changes somewhere else. For example; when air themperatures rise, the oceans absorb more heat from the atmosphere and become warmer. Warmer oceans in turn, can cause stronger storms

 

Weather is a specifik event or condition that happens over a period of hours or days. For example, a thunderstorm, snowstorm and todays temperature all describe weather.

Climate refers to average weather conditins over many years (usually at least 30 years) . The averge climate around the world is called global warming. 

 

Weather conditions can change from one year to the next but when the average pattern over many years changes, it could be a sign of climate change.

 

 

 

 

 

 

 

 

 

 

More than 100 years ago, people around the world started burning large amounts of coal, oil and natural gas to power their homes, factories and vehicles. Today, most of the world relies on these fossil fuels for their energy needs. Burning fossil fuels releases carbon dioxide, a heat- trapping gas, into the atmosphere, which is the main reason why the climate is changing.

 

Heat- trapping gases are also called greenhouse gases. They exist naturally in the atmosphere, where they help keep the earth warm enough for plants and animals to live. But people are adding extra greenhouse gases in the atmosphere. These gases are causing the earth to get warmer, setting of all sorts of other changes around the world. On land, in the oceans and in the atmosphere. These changes effect people, plants and animals in many ways. 

 

 

 

If it was not for greenhouse gases trapping heat in the atmosphere, the earth would be a very cold place. Greenhouse gases keep the earth warm throuh a process called the greenhouse effect. 

 

Play this video to learn more 

youtu.be/VYMjSule0Bw

 

 

The earth gets energy from the sun in the form of sunlight. the earth's surface absorbs some of this energy and heats up. that's why the surface of a road can feel hot even after the sun has gone down, because it has absorbed a lot of energy from the sun.The earth cools down by giving off a different form of energy, called the infrared radiation. But before  all this radiation can escape to outerspace, greenhouse gases in the atmosphere absorb some of it, which makes the atmosphere warmer. As the atmosphere gets warmer it makes the earth's surface warmer too. 

 

Greenhouse gases trap heat in the atmosphere, which makes the earth warmer, people are adding several types of greenhouse gases to the atmosphere and each gas's effect on climate change depends on three main factors.

 

How much?

 

People produce larger amounts of some greenhouse gases than others. Carbon dioxide is the greenhouse gas you hear people talk about the most. That's because we produce more carbon dioxide than any other greenhouse gas, and it's responsible for most of the warming.

 

How long?

 

Some greenhouse gases stay in the atmosphere for only a short time, but others can stay in the atmosphere and effect the climate for thousands of years.

 

How powerful?

 

Not all greenhouse gases are created equal! Some trap more heat than others. For example, one pound of methane traps about 21 times as much heat as one pound of carbon dioxide. .

Carbon dioxide is the most important greenhouse gas emitted by humans, but several other gases contribute to climate change too.

 

 

 

 

 

 

The size of each piece of the pie represents the amount of warming that each gas is currently causing in the atmosphere as a result of emissions from people's activities.Source: Intergovernmental Panel on Climate Change, Fourth Assessment Report (2007).

 

 

Greenhouse gases come from all sorts of everyday activities such as using electricity, heating our homes, and driving around town. The graph below shows which activities produce the most greenhouse gases in the United States.

These greenhouse gases don't just stay in one place after they're added to the atmosphere. As air moves around the world, greenhouse gases become globally mixed, which means the concentration of a greenhouse gas like carbon dioxide is roughly the same no matter where you measure it. Even though some countries produce more greenhouse gases than others, emissions from every country contribute to the problem. That's one reason why climate change requires global action. The graph below the first shows how the world's total greenhouse gas emissions are continuing to increase every year.

 

The atmosphere isn't the only part of the earth that has carbon. The oceans store large amounts of carbon and so do plants, soil, and deposits of coal, oil, and natural gas deep underground. Carbon naturally moves from one part of the earth to another through the carbon cycle. But right now, by burning fossil fuels, people are adding carbon to the atmosphere (in the form of carbon dioxide) faster than natural processes can remove it. That's why the amount of carbon dioxide in the atmosphere is increasing, which is causing global climate change.

Check out this video to learn more about the carbon cycle and how people are changing the natural balance.

youtu.be/vrDekmRbBVk

People are adding cabon dioxyde to the atmosphere faster than it can be removed.

 

The earth's climate in the past

The Earth was formed about 4.5 billion years ago—that's a very long time ago! It's hard to say exactly what the Earth's daily weather was like in any particular place on any particular day thousands or millions of years ago. But we know a lot about what the Earth's climate was like way back then because of clues that remain in rocks, ice, trees, corals, and fossils.

These clues tell us that the Earth's climate has changed many times before. There have been times when most of the planet was covered in ice, and there have also been much warmer periods. Over at least the last 650,000 years, temperatures and carbon dioxide levels in the atmosphere have increased and decreased in a cyclical pattern. Can you see this pattern in the graph below?

 

 

 

These graphs are based on the Vostok ice core from Antarctica. They do not include the most recent increases in carbon dioxide and temperature caused by humans. Notice the strong connection between carbon dioxide and temperature. Source: EPA's Climate Change Indicators (2014) and Petit et al. (2001)

 

 

 

 

The shape of the Earth's orbit around the sun naturally changes over time, and so does the way the Earth tilts toward the sun. Many of these changes happen in cycles that repeat over tens of thousands of years. These changes affect how much of the sun's energy the Earth absorbs, which in turn affects the Earth's temperature. Over at least the last few million years, these cycles likely caused the Earth to alternate between cold and warm periods. For the last few thousand years, we've been in a relatively warmer period.

 

 

 

The sun goes through sunspot cycles every 11 years or so. During times when there are sunspots, dark spots—some as big as 50,000 miles wide—move across the surface of the sun. When this happens, the sun gives off slightly more energy, which makes the Earth a bit warmer. The sun also goes through longer term changes that affect how much energy it gives off.

 

 

 

 

 

 

The Earth's first billion years were very different from the conditions today. The sun was cooler then, but the planet was generally warmer. That's because there were a lot of greenhouse gases, like carbon dioxide and methane, in the atmosphere. Also, the atmosphere back then contained very little oxygen. It was a very different world—a world without people or the kinds of plants and animals that thrive in today's climate. But photosynthesis, which became common about 2 billion years ago, changed all that. During photosynthesis, plants take carbon dioxide out of the atmosphere and replace it with oxygen. Photosynthesis permanently changed the atmosphere by adding more oxygen to the air while reducing the amount of greenhouse gases.

 

 

 

 

 

 

When volcanoes erupt, they spew more than red hot lava! They also add carbon dioxide to the atmosphere, along with dust, ash, and other particles called aerosols. At certain times during the history of the Earth, some very active volcanoes added a lot of carbon dioxide to the atmosphere, causing the planet to get warmer. However, most of the time, including today, the major effect from volcanoes is actually cooling the Earth because aerosols block some sunlight from reaching us. If an eruption is big enough to launch these particles high into the atmosphere, it can lead to slightly cooler temperatures around the world for a few years.

 

 

 

 

Today's climate change is different from past climate change in several important ways:

1. Natural causes are not responsible.None of the natural causes of climate change, including variations in the sun's energy and the Earth's orbit, can fully explain the climate changes we are seeing today. 
2. People's activities are the main cause. By burning lots of fossil fuels like coal, oil, and natural gas, people are overloading the atmosphere with carbon dioxide and adding to the greenhouse effect. People are also adding other heat–trapping greenhouse gases, such as methane and nitrous oxide, to the atmosphere.
3. Greenhouse gases are at record levels in the atmosphere. For hundreds of thousands of years, the concentration of carbon dioxide in the atmosphere stayed between 200 and 300 parts per million. Today, it's up to nearly 400 parts per million, and the amount is still rising. Along with other greenhouse gases, this extra carbon dioxide is trapping heat and causing the climate to change.

 

 

Source: EPA's Climate Change Indicators (2014).