When people talk about Global warming, they mean the average surface temperature of Earth is getting warmer. This is mostly caused by people releasing carbon dioxide in the air by burning fossil fuels such as coal and oil. These fuels contain carbon that has been stored in plants for millions of years through photosynthesis. By adding carbon back into the atmosphere, humans are changing the planet’s climate by raising the temperature of the Earth’s surface and the oceans.
Since the Industrial Revolution, the concentration of carbon dioxide in the atmosphere has increased each year. Since the 1960s, it has grown faster than ever before. Carbon dioxide levels are currently higher than at any time in the last 650,000 years. The increase is occurring 100-200 times faster than the rate of increase in atmospheric temperatures at the end of the last ice age.
While there have been natural causes of warming such as volcanic eruptions and changes in the amount of sunlight reaching Earth, scientists have unequivocally concluded that human activities are responsible for the current warming trend. This conclusion is based on the physics of how greenhouse gases act to trap heat in Earth’s atmosphere.
The current warming trend has already resulted in some important effects such as sea level rise, droughts, floods and wildfires. In addition, the warming has altered biological processes such as tree leaf growth and animal hibernation patterns. It is likely that these trends will continue to accelerate unless we reduce our emissions and remove carbon from the atmosphere. This is called achieving net zero carbon dioxide emissions, and most countries have now or will soon adopt this goal.
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