Redefining 'Normal Weather'

Whether it's because of human influence, climate change, or something else entirely, it is undeniable that weather conditions across the globe are changing. In light of this, the World Meteorological Organization (WMO) has recently called to update the definition of "normal" weather.

Last week, the WMO Commission for Climatology issued a recommendation that all governments adapt a two-tier approach to updating baselines for local meteorological monitoring services.

These baselines serve as a sort of tool for comparison based on 30-year averages of "climate normals" characterized by temperature and participation patterns.

Unfortunately, these baselines are updated only every 30 years, meaning that the current baseline reflects climate normals for 1961-1990. The WMO expressed their concern that the massive changes in atmospheric churning that has occurred within the last decade or so could have led to changes so extreme that the 1990 data is out of date - thus, decision makers in "climate-sensitive industries" have been basing their work around an obsolete baseline.

To correct this, many national weather services have started to use 30-year baselines from 1981-2010. The WMO is also proposing a new system in which the baselines are updated every 10 years while maintaining a 30-year average. In this way, baselines used in the 2020s would be the 1991-2020 baseline, and the 2030 baseline would span from 2001 to 2030.

"Today's increasingly powerful computers and climate data management systems now make it much easier to conduct more frequent updates, which involve analyzing massive amounts of climate data," said Michael Williams, a WMO representative. "Another advantage of decadal updates is that they will make it possible to incorporate data from newly established weather stations into the normals more rapidly."

This proposal of a decadal update of baselines won't be fully agreed upon until June 2015 at a WMO meeting in Geneva.