Yesterday was Earth Information Day, which encouraged engagement between the science community and other stakeholdes and provided an up–to-date picture of the state of the climate and an outlook on developments and opportunities.
WCRP's Director, David Carlson, gave a presentation on 'Products and indicators to monitor the state of the climate system' (slides, webcast (at 1:43:04)). The take home message is that there are three main indicators that provide a good measure of the state of the climate system: heat/energy, carbon (CO2 and CH4) and sea level (heat/water). These indicators also have in common that they are assembled and calibrated by large teams of researchers, are open access, are reviewed and published in the Earth System Science Data journal and can be supplied on annual (or at least less than 5 year) timescales.
For more information on Earth Information Day also see this collection of impressions from UN Adaptation.