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Much of this energy goes out into space – but not all. We see some of the energy emitted by the Sun because the Sun is hot and hotter objects emit radiation in the visible part of the electromagnetic spectrum.īecause Earth is much cooler than the Sun, the radiation it emits is invisible, at long infrared wavelengths. When the Sun’s light and heat hits Earth, some is absorbed at the surface and some is reflected back out into space. That makes us dependent on another source of heat – the Sun. Little of the Earth’s internal heat gets through to the cold crust where we live. One reason we’re alive is that our planet orbits in the Goldilocks zone, just the right distance from the Sun to be not too hot and not too cold. But then a runaway greenhouse effect took place, trapping truly enormous quantities of heat. That’s due to an atmosphere much thicker than Earth’s, dense in carbon dioxide. That’s why the second planet, Venus, is the hottest in the solar system, at an average of 464℃. It gets hot, at an average temperature of 167℃. Mercury is the closest planet to the Sun. Life on Earth is possible because we’re in a sweet spot – not too hot, not too cold. It’s no wonder we’re seeing rapid warming in our oceans. (The world’s average surface temperature in the 20th century was 13.9℃.)īut almost all of this energy to date has been taken up by the oceans. Recent research shows we’ve added the energy of 25 billion nuclear bombs to the Earth system in just the last 50 years.īillions of nuclear bombs to produce 1.2℃ of heating – so what? It seems small, considering how much temperature varies on a daily basis. To warm the entire planet takes an extraordinary amount of extra energy. That’s because adding new carbon to the world’s natural carbon cycle has caused an imbalance in the amount of energy entering and leaving the Earth system. The current result? The average temperature at the planet’s surface is about 1.2℃ hotter than in the pre-industrial era. We’ve now converted coal, oil and gas into more than two trillion tonnes of heat-trapping carbon dioxide and other greenhouse gases and added them to the atmosphere. Since the 18th century, humans have been taking fossil fuels out of their safe storage deep underground and burning them to generate electricity or power machinery.