The objectives of the CRP are (i) to improve the capability of member states to investigate the El Ni?o phenomenon in the ocean, (ii) to contribute to better understanding its past behaviour and to predict possible scenarios for the future, (iii) to explore the applications of recent nuclear and isotopic techniques suitable for the quantitative estimation of past el ni?o events. the CRP will co-ordinate efforts in the use of nuclear and isotopic techniques for studying isotope records in corals, seawater and sediment with the aim of deriving past temperature records in the pacific ocean. for this purpose, analysis of stable isotopes (d/h, 18o/16o, 13c/12c, sr/ca, u/ca), natural (210pb, 226ra, th and u isotopes) and cosmogenic/anthropogenic (3h, 10be, 14c) radionuclides will be carried out in coral, seawater and sediment samples collected in the Pacific regions using radiometric and mass spectrometry techniques. in addition to nuclear techniques, chemical and remote sensing techniques will also be applied as complementary tools. It is intended that the contract and agreement holders, to be selected for participation in the CRP, will apply their techniques in two or three reference sites where active programmes for investigations of the El Ni?o phenomenon and related aspects are being carried out.