Global team of scientists determine 'fingerprint' for how much heat, drought is too much for forestshttps://phys.org/news/2022-04-global-team-scientists-fingerprint-drought.htmlJust published in the journal Nature Communications, the study compiles the first global database of precisely georeferenced forest die-off events, at 675 locations dating back to 1970. The study, which encompasses all forested continents, then compares that information to existing climate data to determine the heat and drought climatic conditions that caused these documented tree mortality episodes.
"In this study, we're letting the Earth's forests do the talking," said William Hammond, a University of Florida plant ecophysiologist who led the study. "We collected data from previous studies documenting where and when trees died, and then analyzed what the climate was during mortality events, compared to long-term conditions."
After performing the climate analysis on the observed forest mortality data, Hammond noted, a pattern emerged.
"What we found was that at the global scale, there was this consistently hotter, drier pattern—what we call a 'hotter-drought fingerprint' – that can show us how unusually hot or dry it has to get for forests to be at risk of death," said Hammond, an assistant professor in the UF/IFAS agronomy department.
The fingerprint, he says, shows that forest mortality events consistently occurred when the typically hottest and driest months of the year got even warmer and drier.
"Our hotter-drought fingerprint revealed that global forest mortality is linked to intensified climate extremes," Hammond said. "Using climate model data, we estimated how frequent these previously lethal climate conditions would become under further warming, compared to pre-industrial era climate—22% more frequent at plus 2 degrees Celsius (plus 3.6 degrees Fahrenheit), to 140% more frequently at plus 4 degrees Celsius (plus 7.2 degrees Fahrenheit