Over the course of the Earth’s 4.5-billion-year history, the climate has changed a lot. This is true. But the rapid warming we’re seeing now can’t be explained by natural cycles of warming and cooling. The kind of changes that would normally happen over hundreds of thousands of years are happening in decades.
Global temperatures are now at their highest since records began. In fact, 17 of the 18 warmest years on record have all taken place since 2001.
This much faster warming corresponds with levels of carbon dioxide in the atmosphere, which have been increasing since the industrial revolution. So, when people talk about climate change today, they mean anthropogenic (man-made) climate change. This is the warming of Earth’s average temperature as a result of human activity, such as burning coal, oil and gas to produce energy to fuel our homes and transport and cutting down trees to produce the food we eat.
Direct observations made on and above Earth’s surface show the planet’s climate is significantly changing. Human activities are the primary driver of those changes.
Earth’s climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 11,700 years ago marking the beginning of the modern climate era — and of human civilization. Most of these climate changes are attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives.
