Retreat of glaciers since 1850 doing so due to transient local weather conditions, which have brought more precipitation and cloudier, cooler summers since 2002. Tropical glaciers are located between the Tropic of Cancer and the Tropic of Capricorn, in the region that lies 23° 26′ 22″ north or south of the equator. Strictly, a tropical glacier is located within the astronomical tropics; the area where the annual temperature variation is less than the daily variation, and is within the oscillation area of the Intertropical Convergence Zone. Tropical glaciers are the most uncommon of all glaciers for a variety of reasons. Firstly, the regions are the
Cool tropics paradox poleward heat transport by the oceans, and vegetational responses at high latitudes, were proposed, but these didn't fully explain behaviour in the southern hemisphere, and winter, respectively. Data from terrestrial proxies suggested that the equator may have reached 30 °C - however, this figure is based upon extrapolation of data found outside the tropics. This would imply that the foramaniferal proxies were wrong - the tests may perhaps have been overprinted by diagenesis. Researchers turned to shallow marine molluscs as it is easy to determine whether their shells had been altered by diagenesis. Many mollusc shells are constructed from aragonite,