What is Global Warming?

It seems a bit obvious, right? The globe is warming because all the different parts of the Earth (atmosphere, oceans, land, even the ice) are storing up heat. This means that oceans get warmer and the ice starts melting—but there is more to it. John Cook, Climate Communication Fellow at the Global Change Institute at the University of Queensland, explains.

Researchers have developed different ways to measure global warming. They use thermometers to measure the temperature of the air and the oceans and satellites circling around the Earth to assess what’s happening to the ice on our planet’s surface.

These measurements show our planet has been steadily storing up heat over the last 50 years.

Global warming can be caused by a number things. When something gets warm, it cools by giving off its heat. You can feel this by putting your hands near a hot object and feeling the warmth coming off. The Sun warms up our planet, and the Earth cools by releasing heat to space. When the Earth is in balance, the heat from the Sun is balanced by the heat we lose to space.

But sometimes things get out of balance. For example, if the sun gets hotter, we absorb more sunlight and our planet stores up heat. Another cause of global warming is heat-trapping gases called greenhouse gases. They act like a blanket, slowing down the Earth’s cooling by trapping some of the heat escaping to space.

When our parents or neighbours drive their cars or when we use electricity, we often burn coal or oil. Burning coal or oil gives off a greenhouse gas called carbon dioxide. This is like adding extra heat-trapping blankets to the atmosphere. All the extra greenhouse gases in the atmosphere trap more heat. This causes global warming.

Humans are pouring billions of tonnes of carbon dioxide every year. This is dramatically increasing the amount of heat trapping gases in the atmosphere. The amount of heat we’ve been storing up is equivalent to over 2 atomic bombs worth of heat going off every second for the last 50 years!

And yes, despite what you might hear somewhere else: humans have caused most of the global warming over the past 50 years.

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