Future big droughts may be worse than we think - NZ's past shows why

New Zealand’s Climate Change Commission highlights worsening drought risks, but recent research challenges assumptions about modern extremes by uncovering three of the country’s most severe droughts—all predating 1950. The study, using rainfall deficit records from 97 high-quality weather stations dating back to the 1860s, found the most intense drought began in winter 1914 and lasted until at least February 1915. Over half of the stations recorded their five driest periods on record during this event, with widespread shortages across the North Island and eastern South Island. Modern drought assessments often rely on the Virtual Climate Station Network, which only provides reliable data since the 1970s, missing earlier severe events. The new research fills this gap by focusing on rainfall deficits, revealing that the 1914–1915 drought was unprecedented in duration and severity. This contradicts the belief that New Zealand’s worst droughts occurred in recent decades, such as the 2007–08 drought in Waikato, which quadrupled silage prices and cost the economy several billion dollars. The 2012–13 drought, covering the entire North Island, reduced national economic output by 0.7% of GDP, a scenario still used by the Reserve Bank for agricultural lending-risk assessments. However, the historical data suggests these modern events may not represent the worst-case scenarios. The 1914–1915 drought’s intensity and duration were far greater, with severe shortages persisting through summer. The findings underscore the need to reconsider drought risk assessments, as modern tools underestimate past extremes. The study’s authors argue that policymakers must incorporate longer-term historical data to better prepare for future climate challenges. This could help New Zealand avoid underestimating the economic and agricultural impacts of severe droughts in a warming world.