Energy
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15.The energy problem

Figure 6.23. Global sources for energy from 2000 to 2020. The trend since 2015 is also highlighted in this chart.
Humankind has always needed energy, and while the source and usage of energy have changed over time some patterns have remained constant.

In earlier times food was the key source of energy for people and their livestock.

From the burning of wood and coal to nuclear power, the development of energy sources has been crucial to the advancement of society.

Figure on the left shows the mix of energy resources used worldwide from 2000 to 2020.

Fossil fuels still provide most of the world’s energy, with oil being the single most commonly used energy resource.

Emissions from fossil fuels are the dominant cause of global warming.

In 2018, 89% of global CO2 emissions came from fossil fuels and industry.

Natural gas is used less than the other two fossil fuels, but even natural gas is used more than all renewable energy resources combined.

Wind, solar, and geothermal energy contribute the least to global energy use, despite the fact that they are virtually limitless in supply and non-polluting.

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