evidence: Over the course of Earth’s 4.5-billion-year history, the climate has changed a lot, this is true. However, 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. [...] So, when people talk about climate change today, they mean anthropogenic (human-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. You can read more about it here: How do we know climate change is real? [...] We’re already seeing the devastating effects of climate change on global food supplies, migration, conflict, disease and global instability, which will only get worse if we don’t act now. Human-made climate change is the biggest crisis of our time. It threatens the future of the planet that we depend on for our survival and we're the last generation that can do something about it.