Isotope variability of rain for assessing climate change impacts

Seventeen Member States, representing five different continents, have participated in the CRP, contributing important data on isotopes in precipitation. The CRP involved measurement of naturally occurring stable and radioactive isotopes of the water molecule in precipitation and water vapor, and numerical evaluations of isotopes in the water cycle. The CRP successfully addressed and filled major gaps in the records of isotopic composition of precipitation in the tropics and in the mid-latitudes, including data collected from more than 125 stations across the globe. The isotope database generated in the framework of this CRP is relevant for the use of stable isotopes in various scientific disciplines and many other practical and scientific applications. It supports a better understanding of the atmospheric circulations and meteorological processes responsible of the observed isotope variability in the data. Outcomes of this CRP have already influenced and have been used in several national research projects and in TC projects (particularly in Europe and in Latin America). Furthermore valuating these isotope data will eventually impact important scientific questions in the subject area, like the re-assessment of the Global Meteoric Water Line, or the ongoing discussion about interpreting isotopes for the stratiform vs convective rainfall distribution.