Future big droughts may be worse than we think – NZ’s past shows why

New Zealand’s Climate Change Commission has highlighted the growing threat of severe droughts, particularly in the drier northern and eastern regions, as the planet warms. Recent droughts—such as the 2007–08 event in Waikato, which quadrupled silage prices and cost the economy billions—have demonstrated their economic toll. A 2012–13 drought across the North Island reduced national GDP by up to 0.7%, prompting the Reserve Bank to use it as a worst-case scenario in agricultural lending risk assessments. However, new research suggests New Zealand’s most extreme droughts have been overlooked in modern policymaking. Scientists analyzed rainfall deficits from high-quality weather stations with records dating back to the 1860s, identifying three of the worst droughts in history—all occurring before 1950. The most severe began in winter 1914, lasting until at least February 1915, with rainfall deficits unmatched in the instrumental record. Over half of all stations recorded one of their five driest periods during this time, indicating an unprecedented multi-year drought sequence. The 1914–15 drought was far more widespread than recent events, affecting the North Island and eastern South Island. While late-winter droughts, like the 1993 Auckland water crisis, have occurred, none compare in scale. Another extreme drought, from July 1907 to February 1908, produced the most widespread summer rainfall deficits, with many South Island stations recording their driest conditions on record. The study highlights gaps in modern drought assessments, which rely on data only stretching back to the 1970s. By focusing on long-term rainfall records, researchers found that early 20th-century droughts exceeded recent events in both intensity and duration. This suggests future droughts could be even more severe than currently projected, posing greater risks to agriculture and the economy.