Measuring Drought

This week, we’re looking at recent research on water and climate. Today, we’ll look at drought-measuring techniques.

Since the mid-1960s, the Palmer Drought Severity Index (PDSI) has been the standard of measuring drought, reviewing temperature and rainfall information over a period of time. But a recent study in Nature states that the measurement may be too simple.

The PDSI looks at potential moisture evaporation from the soil in terms of temperature and plant use. But researchers at Princeton University see other clues to evaporation—wind speed, humidity and solar radiation—that could contribute to the evaporation and drought estimation.

The Intergovernmental Panel on Climate Change (IPCC) uses the PDSI to assess drought. In their 2007 report, they noted that droughts have intensified since the 1970s. But the Princeton team finds that there has been little change in droughts over the past 60 years. According to Science Now,

… the new assessment technique found that between 1980 and 2008, the global area stricken by drought grew by approximately 0.08% per year—less than one-seventh the increase estimated by the temperature-only version of PDSI…

The results of the study have implications for how we interpret the role of global warming on changes to the weather and its extremes like drought. The authors stress that this finding does not rule out drought as a response to future climate change. It just gives scientists a better way to measure and predict drought.

Tomorrow: Sustainable groundwater