researchers found that annual air temperatures, over land and at mid-latitude, averaged about 23–29 °C (± 4.7 °C), which is 5–10 °C higher than most previous findings. Pseudoproxies The skill of algorithms used to combine proxy records into an overall hemispheric temperature reconstruction may be tested using a technique known as "pseudoproxies". In this method, output from a climate model is sampled at locations corresponding to the known proxy network, and the temperature record produced is compared to the (known) overall temperature of the model. See also Dendrochronology Historical climatology, the study of climate over human history (as opposed to the Earth's) Ice core Paleotempestology Paleothermometer Palynology Speleothem References Further reading "Borehole Temperatures Confirm Global Warming Pattern." UniSci. 27 Feb. 2001. 7 Oct. 2009. Bruckner, Monica. "Paleoclimatology: How Can We Infer Past Climates?" Microbial Life. 29 Sept. 2008. 23 Nov. 2009. "Climate Change 2001: 2.3.2.1 Palaeoclimate proxy indicators." IPCC. 2003. Sept. 23, 2009. "Coral Layers Good Proxy for Atlantic Climate Cycles." Earth Observatory. Webmaster: Paul Przyborski. 7 Dec. 2002. 2 Nov. 2009. "Core Location Maps." National Ice Core Laboratory. 9 Apr. 2009. 23 Nov. 2009. "Dendrochronology." Merriam-Webster Online Dictionary. Merriam-Webster Online. 2009. 2 Oct. 2009. Environmental News Network staff. "Borehole temperatures confirm global warming." CNN.com. 17 Feb. 2000. 7 Oct. 2009. "The GRIP Coring Effort." NCDC. 26 Sept. 2009. "Growth ring." Encyclopædia Britannica. Encyclopædia Britannica Online. 2009. 23 Oct. 2009. Huang, Shaopeng, et al. "Temperature trends over the past five centuries reconstructed from borehole temperatures." Nature. 2009. 6 Oct. 2009. "Objectives – Kola Superdeep Borehole (KSDB) – IGCP 408: 'Rocks and Minerals at Great Depths and on the Surface.'" International Continental Scientific Drilling Program. 18 July 2006. 6 Oct. 2009. "Paleoclimatology: the Oxygen Balance." Earth Observatory. Webmaster: Paul Przyborski. 24 Nov. 2009. 24 Nov. 2009. Schweingruber, Fritz Hans. Tree Rings: Basics and Application of Dendrochronology. Dordrecht: 1988. 2, 47–8, 54, 256–7. Strom, Robert. Hot House. New York: Praxis, 2007. 255. "Varve." Merriam-Webster Online Dictionary. Merriam-Webster Online. 2009. 2 Nov. 2009. Wolff, E. W. (2000) History of the atmosphere from ice cores; ERCA vol 4 pp 147–177 External links Chemical climate proxies at Royal Society of Chemistry, January 23, 2013 Quintana, Favia et al., 2018 ″Multiproxy response to climate- and human-driven changes in a remote lake of southern Patagonia (Laguna Las Vizcachas, Argentina) during the last 1.6 kyr″, Boletín de la Sociedad Geológica Mexicana, Mexico, VOL. 70 NO. 1 P. 173