Glacier monitoring has been done for over 125 years, but it's unclear which glaciers are the biggest. A new study has identified the largest glaciers in the world, not including ice sheets in Greenland and Antarctica. The researchers ranked glaciers by area, considering factors like how they are defined and mapped. The biggest glacier complexes are tens of thousands of square kilometers, while the largest glaciers are several thousands of square kilometers. The largest glaciers and glacier complexes are found in Antarctica, the Arctic, and Patagonia.