This document discusses NASA's big data challenges in climate science. It notes that by 2020, climate data holdings from simulations, observations, and reanalyses are projected to grow to hundreds of exabytes worldwide. It describes NASA's efforts to build "data analytics platforms" like NEX and Obs4MIPs using ESGF to enable analysis of large amounts of observational and modeling data without needing to download entire datasets locally. The challenges of remote data visualization, distributed data analysis, and data management for big climate data are also discussed.