The Earth has always changed. Ice ages have come and gone, oceans have risen and receded, and species have evolved and vanished. But the pace of change we are now experiencing is different. It's faster, more widespread, and—most importantly—driven not by natural forces alone, but by human activity. This phenomenon, broadly known as climate change, is one of the defining challenges of the 21st century.

From the highest mountain peaks to the deepest ocean trenches, no part of the Earth is untouched by the warming atmosphere and shifting climate. We are entering an era where the very systems that support life—air, water, land, and biological diversity—are being pushed beyond their limits. As climate patterns shift, ecosystems strain under the pressure, and human health faces new and evolving threats.

But to understand how we got here and where we are headed, we must first understand what climate change truly is.