Stable isotope proxy records in tropical terrestrial environments

The 'tropics' refers to an area that is loosely equatorial, characterized by relatively high temperatures (at low altitude), comparatively low seasonal contrast in temperatures and generally high, or highly seasonal, rainfall. The stable isotopes of carbon, oxygen and hydrogen are increasingly important tools of relevance to understanding trajectories and mechanisms of past environmental change in the tropics. In the case of carbon this is because, at the broadest level, the carbon isotope composition of organic and carbon-containing inorganic proxy materials formed in the tropics can be read as being derived from the balance between C-3 (tree) and C-4 (grass) photosynthesis, hence providing a relative measure of vegetation type and, indirectly, climate. Likewise, changes in the oxygen and hydrogen isotope composition of many proxy materials, again at the broadest level, can be read as indicative of changes in hydrological conditions and/or altitude in the past. This review provides an entry point into the literature relating to the use of stable isotopes as terrestrial environmental proxies for past environmental change, with a focus on the measurement and interpretation of stable isotope data from the wide range of proxy materials preserved in tropical environments.