As the planet’s air conditioner, the polar ice caps impact weather and climate dynamics, such as the jet stream. Glaciers are also early indicators of climate changes that will have a somewhat more delayed impact on other parts of the Earth system. Glaciers are sentinels of climate change. They are the most visible evidence of global warming today. In addition to raising sea water levels, widespread loss of glaciers will likely alter climate patterns in other, complex ways. For example, glaciers’ white surfaces reflect the sun’s rays, helping to keep our current climate mild. When glaciers melt, darker exposed surfaces absorb and release heat, raising temperatures. Our way of life is based on climate as we know it.