This thesis provides a palaeolimnological and environmental reconstruction of the last ~2,800 years of Lake Siscunsí, located in the Eastern Cordillera of Colombia. This study is mainly based on a high-resolution diatom record in combination with Chlorophyll 𝑎 and other analyses previously done in this lake, which include grain size, C/N, δ15N, δ13C, TOM, total carbonates and magnetic susceptibility. It consists of a review of the mid and late Holocene climates in Colombia, then it summarizes the most important findings in the palaeorecords of the three Colombian cordilleras and it briefly mentions the most significative periods of human effects. It focuses on describing the main environmental and limnological changes ocurred from ~2,854 cal yr BP until present. It describes diatom assemblage changes with the aid of the previously mentioned proxies. Diatoms were grouped by its habitat type, however the most dominant fossil diatom in this record is a new taxon, and therefore diatom guilds were used to interpret limnological changes. Four main periods of environmental and limnological changes were recorded: (1) From ~2,854 to 1,976 cal yr BP the lake was under low hydraulic energy, representing relatively dry conditions, with low nutrient levels and lacustrine algae as the main source of organic matter; (2) from ~1,976 to 1,572 cal yr BP the littoral area expanded under more humid conditions, with an increase of C and N, where C3 plants and macrophytes were important contributors of organic matter; (3) from ~1,572 to 535 cal yr BP the driest conditions in the entire record occurred along with nutrient enrichment originated by C3 plants and CAM macrophytes; (4) from ~535 to 349 cal yr BP there was a transition to humid conditions and decreased levels of nutrients under a highly disturbed environment. These conditions continued from ~349 to the present when human impact was a modifier to Lake Siscunsí dynamics. Humid/dry episodes in the record as well as in the last decades coincide with the increases/decreases in frequency and intensity of ‘El Niño’ events in Northern South America, being this phenomenon a possible cause of the environmental conditions recorded in the lake.