30 then and now photos that show dramatic changes on Earth

Throughout the planet’s 4.5-billion-year history, the Earth has undergone amazing and dramatic changes. Even today, the planet is in a constant state of flux, and while some of the changes it has undergone are caused by mankind, many others are not.

These changes have resulted from the moving of continents, the formation of mountain ranges, powerful volcanic eruptions, glaciers advancing and retreating, catastrophic megafloods and extreme climate changes across the globe. Even the Earth's highest peaks have been eroded by the forces of water and wind over the inevitable duration of time.

“Alaska has been warming at nearly two times the rate as the rest of the U.S. over the past 50 years,” AccuWeather.com Meteorologist Brett Anderson said, referring to the decline in Alaska’s glaciers over the past century.

“More specifically, the state as a whole has warmed a little more than 3 degrees Fahrenheit over the last six decades," he said, adding that since 1977 the rate of warming has been much lower and may be due to changing wind and ocean current patterns in the Pacific.

Move your cursor over these recent NASA images below to reveal the dramatic changes the Earth has undergone throughout this photographic history.