The IRI/LDEO Climate Data Library contains over 300 datasets from a variety of earth science disciplines and climate-related topics. It is a powerful tool that offers the following capabilities at no cost to the user:
access any number of datasets;
create analyses of data ranging from simple averaging to more advanced EOF analyses;
monitor present climate conditions with maps and analyses in the Maproom;
create visual representations of data, including animations;
download data in a variety of commonly-used formats, including GIS-compatible formats
While you are welcome to acknowlege the LDEO/IRI Data Library, it is not required. The proper docementation and references for the datasets within the Data Library can be found with the "dataset documentation" link on the dataset source page.