Published in the journal Nature<\/a>, this study analyzes data gathered from multiple datasets, including forest demographic data from selective logging sites in the Amazon. What the findings showed is that by the year 2100, this world-famous rainforest\u2014known aptly as the \u201clungs of the planet<\/a>\u201d\u2014is evolving into a biome that has no modern equivalent. Known as the \u201chypertropics,\u201d this biome features extended dry seasons, even hotter temperatures, and longer periods of hot drought, increasing tree mortality by 55 percent. While annual tree mortality is currently a little more than one percent, the authors say that this increase will have substantial knock-on effects.<\/p>\n Related Story<\/p>\n This increased forest dieback isn\u2019t only bad news for the local fauna and flora. Biomes like the Amazon<\/a> are also the best-equipped at pulling carbon from the atmosphere, meaning that the emergence of the \u201chypertropics\u201d will inevitably impact humanity\u2019s efforts to cool down the planet. In other words, that once well-oiled machine is beginning to break down. <\/p>\n \u201cPresent-day hot droughts are harbingers of this emerging climate<\/a>, offering a window for studying tropical forests under expected extreme future conditions,\u201d the authors wrote in the study. \u201cUnder a hypertropical climate, temperature and moisture conditions during typical dry season months will more frequently exceed identified drought mortality thresholds, elevating the risk of forest dieback.\u201d<\/p>\n The main problem at the heart of this emerging biome is that extended droughts will drop soil moisture content by volume. Once this number reaches a threshold of about 0.32 percent\u2014only a third of the soil\u2019s pores are filled with water<\/a>\u2014transpiration rates in trees drop rapidly, which greatly increases stress. This causes trees to shut down carbon capture entirely, which either effectively starves them or creates air bubbles in the tree\u2019s sap, the latter of which the authors describe as a type of plant-based embolism. <\/p>\n \u201cNormally, plants<\/a> are pretty good at trying to compartmentalize and just say, \u2018OK, I’m willing to sacrifice that branch to keep this core piece alive,\u2019\u201d Jeffrey Chambers, the lead author of the study from the University of California Berkeley, said in a press statement. \u201cBut if there are enough embolisms, the tree just dies.\u201d<\/p>\n Related Story<\/p>\n Although the hypertropics have no modern analog, this type of climate did exist tens of millions of years ago, when the Earth<\/a> was much hotter. But it appears that it\u2019s poised for a comeback\u2014and not just in the Amazon. According to the researchers, areas of western Africa and across Southeast Asia could also slip into a hypertropic biome by the end of the century. <\/p>\n
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