RCP4.5 and RCP6.0

Two intermediate stabilization pathways in which radiative forcing is stabilized at approximately 4.5 W m-2 and 6.0 W m-2 after 2100. Source:


One high pathway for which radiative forcing reaches greater than 8.5 W m-2 by 2100 and continues to rise for some amount of time. Source:

Rootzone soil moisture

Water that is available in those parts of the soil from which plant roots can extract water, thereby being an important limiting factor constraining crop productivity. Source:


The flow of water over the surface or through the subsurface, which typically originates from the part of liquid precipitation and/or snow/ice melt that does not evaporate or refreeze, and is not transpired. Source:

Snow storage

Total water mass of the snowpack (liquid or frozen).

Soil moisture

Water stored in the soil in liquid or frozen form. Rootzone soil moisture is of most relevance for plant activity. Source:


Water flow within a river channel, for example, expressed in m3 s-1. A synonym for river discharge. Source:

Water availability

Water availability in a grid cell is the sum of locally generated blue water and the blue water flowing in from upstream grid cells, which intrinsically accounts for upstream water use, minus an environmental flow requirement which amounts to 80% of the naturalized streamflow in the grid cell.

Water scarcity

Water scarcity in a grid cell is the ratio of the local consumptive water use to the total water availability in the grid cell.