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(CNN) --
Climate change: It's a topic you can't avoid, and you'll only hear more about it as the world continues to feel the heat.
Maybe you've watched documentaries about cute endangered polar animals, or tried to read complicated science journals about wildfires, rising ocean levels, or fossil fuels.
The causes of climate change are everywhere, from the clothes you wear to the hamburger you eat, but do you really understand the basics?
At CNN, we recently looked at the most searched climate change questions on Google Trends;
the results revealed that many people are still searching for fundamental answers.
We've put together this list to help you learn more about our changing climate.
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What is climate change?
The term climate change is used to describe a long-term change in global temperatures and weather patterns.
The Earth's temperature has changed dramatically in its 4.5 billion year history, from the Huronia Ice Age, which covered vast portions of the planet in ice for nearly 300 million years, to a period about 50 million years ago. when scientists believe that palm trees and crocodiles were native above the Arctic Circle.
Today, climate change is commonly used as a term to describe the effects of global warming that occurred as a result of human activity after the industrial revolution in the 18th century.
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Why is climate change happening now, what are the causes?
This is where it gets a bit tricky.
Earth's atmosphere is full of gases.
Some gases, including nitrogen and oxygen, which together make up 99% of the gas in the atmosphere, do not absorb heat from the sun, allowing it to be reflected back into space from Earth's surface.
Other gases, known as greenhouse gases, including carbon dioxide, methane, and nitrous oxide, absorb heat and make up about 0.1% of the atmosphere.
When these gases absorb solar energy, they radiate it toward the planet's surface and toward other gas molecules, creating the greenhouse effect.
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The greenhouse effect plays an important role in the natural temperature regulation of our climate.
Without it, the average temperature of the Earth would be -18C.
That's about the temperature of a home freezer.
Since the industrial revolution, the concentration of greenhouse gases in the atmosphere has been increasing as a result of human activities such as the burning of fossil fuels, deforestation, and modern agricultural practices.
Which means more greenhouse effect and more heating.
A 2013 report by the International Panel on Climate Change (IPCC), a body of UN climate scientists, found that the concentration of carbon dioxide in the atmosphere had increased by 40% since the industrial revolution, resulting in in a 1C increase in the Earth's temperature.
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What is the impact of climate change?
The impact of climate change depends on how much the Earth warms.
In 2018, the IPCC published a report on the effects of a 1.5°C rise in temperature.
These include more extreme weather conditions, rising sea levels, destruction of coastal ecosystems, loss of vital species and crops, population displacement, and enormous cost to the global economy.
In 2018, the United Nations warned that, without urgent action, global temperatures will exceed 3°C above pre-industrial levels by the end of the century.
At that temperature, the picture starts to look even worse: Entire cities could be swallowed by rising oceans, plant and animal species will face extinction as their ecological systems fail to adapt to the heat, and hundreds of millions of people could be forced to migrate due to coastal flooding, longer-lasting droughts and depleted crop yields.
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Is climate change real or is it a hoax?
Almost everyone now accepts that the global climate is changing.
The biggest public debate, fueled by high-profile climate skeptics like former US President Donald Trump, is whether climate change is being caused by human activity.
But several studies have shown that the vast majority of scientists agree that climate change is real and caused by humans, with one finding that 97% of the world's scientists agree that global warming caused by humans is happening.
In 2014, 1,300 scientists from around the world contributed to a UN (IPCC) report on the scientific understanding of climate change.
Their report said there was a 95% chance that human activity over the last 50 years had directly resulted in a rise in the Earth's temperature.
Physical evidence of global warming has been found all over the world, from the retreat of glaciers high in the Himalayas to the bleaching of corals in our oceans and the regularity of extreme weather patterns.
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Can climate change be stopped?
But there is hope.
Climate change can be limited and stopped, but only if we take what the IPCC describes as "rapid, far-reaching and unprecedented changes in all aspects of society".
To do this, two things must happen.
First, we need to reverse 250 years of bad environmental habits.
In December 2015, 195 countries agreed to a legally binding framework, the Paris Agreement, to achieve net zero carbon pollution by the end of the century.
The immediate challenge is to slow down and limit global warming to "well below" 2°C above pre-industrial levels.
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A key aspect of this is limiting human practices that create greenhouse gas emissions.
That will mean changes to many aspects of our daily lives, from our diets to the way we travel to how we produce the products we all buy.
The second big challenge is to reverse the effect of those practices by reducing the amount of carbon dioxide (CO2) that is already in the atmosphere.
There have been advances on this front, ranging from high-tech carbon capture technologies to simply planting more trees.
But so far, the IPCC has classified the technology as "unproven" on a scale large enough to move the needle.
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