Study Links California Drought to Climate Change

Although many are hesitant to link any particular weather event to climate change, new research in the Journal Geophysical Research Letters points to a measurable “footprint” of climate change in the 2013-14 drought. Linking this specific drought to climate change is important for at least 2 reasons. First, as the authors point out such linkage can help with prediction of future weather events so we might better plan for them. Second, linking climate change to such a dramatic present day occurrence, provides yet more reason to take action now to reduce future impacts.

The authors of “ Probable causes of the abnormal ridge accompanying the 2013–2014 California drought” focused on a ridge of weather and used climate models to assess possible reasons for the drought. From the abstract,  “The 2013–2014 California drought was initiated by an anomalous high-amplitude ridge system. The anomalous ridge was investigated using reanalysis data and the Community Earth System Model (CESM). It was found that the ridge emerged from continual sources of Rossby wave energy in the western North Pacific starting in late summer and subsequently intensified into winter. The ridge generated a surge of wave energy downwind and deepened further the trough over the northeast U.S., forming a dipole. The dipole and associated circulation pattern is not linked directly with either El Niño–Southern Oscillation (ENSO) or Pacific Decadal Oscillation; instead, it is correlated with a type of ENSO precursor. The connection between the dipole and ENSO precursor has become stronger since the 1970s, and this is attributed to increased greenhouse gas loading as simulated by the CESM. Therefore, there is a traceable anthropogenic warming footprint in the enormous intensity of the anomalous ridge during winter 2013–2014 and the associated drought.”