Why the fires in Hawaii have been so bad
In the Hawaiian language, Lahaina means “cruel sun”. The north-east trade winds provide the eastern shore of Maui with ample rain and the West Maui mountains with a superfluity of it. But Lahaina, the capital of the Hawaiian kingdom in the 19th century, sits in the mountains’ rain shadow and so gets comparatively little. What is more, the rain that does fall does so almost entirely in winter: summers are hot and dry. As a result it is no stranger to fires. But those that ripped through the beautiful city on August 8th and 9th were unprecedented in their fury. As of August 11th at least 55 deaths had been confirmed (and the number was expected to rise), and the damage to the town of around 13,000 people looks well nigh irreparable. Why were these fires so powerful?
Fires need dry fuel. Various factors provided these fires with a lot of it. Hawaii as a whole has been in a drought for over a year, and in Maui conditions recently worsened considerably. American drought-watchers recognise five levels of water stress, from “Abnormally dry” to “Exceptional drought”. In April nowhere in Maui County (composed of Maui and some smaller nearby islands) was abnormally dry, let alone suffering from full-on drought. As of the week of the fires more than a third of the island was in drought conditions and most of the rest was abnormally dry, in part the result of unseasonably hot weather. In Kihei, another town on Maui, the intense sunshine melted traffic lights on their poles.
Over the past decade meteorologists have increasingly talked of “flash droughts”, periods in which dryness increases very quickly because low or no rainfall coincides with sunlight, winds and air temperature, driving evaporation from the soil and water loss through plants into top gear. The rate at which conditions on Maui worsened meets the conditions for a flash drought, Jason Otkins of the University of Wisconsin-Madison told the Associated Press.
2023-08-11 15:00:21
Article from www.economist.com
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