A 258 year-long annual tropical glacial retreat record suggesting warming may not be related to atmospheric CO2 increase

Abstract Glaciers receive more attention in the climate change debate given their high susceptibility to warming. Long records of direct measurements of glacial processes, however, are limited; as a result, reliable annual mass balance records usually cover less than a century. Tropical examples that are believed to be more sensitive to climate change are among the least studied glaciers worldwide. We present the longest known annual glacial retreat record extending to the present, based on annual moraines formed at the retreating terminus of the Tarija Glacier, in the Bolivian Andes. The availability of high-resolution satellite imagery confirms how these ridges form, substantiating a 258-year glacial retreat history. The annual retreat record is validated by correlation with Lake Titicaca surface level evolution: the highest ablation rate matches the highest lake level (1986-1987). Glacial retreat also matches well with a large Pampean foreland lake level evolution (Mar Chiquita), suggesting this glacier reflects continental-scale climate trends. There is, however, no correlation with CO2 concentration curves. The departure of the glacial retreat chronology, considered to be related to warming, from the CO2 evolution over the last 3 centuries, suggests CO2 does not contribute a primary effect on warming, as most models assume. However, small scale climate shifts may be related to a delayed effect of solar irradiance suggesting that the relation between solar irradiance and its impact on Earth’s surface systems needs to be better understood for a critical examination of the climate change paradigm.