California has just wrapped up its fifth year of drought, and although it is too soon to tell what the 2016-17 water year will bring, there will be no immediate relief for Sierra forests. The latest US Forest Service aerial survey (released on 18 November 2016) has identified an additional 36 million trees in the Sierras that have died since the previous survey in May 2016, bringing the total to an unprecedented 102 million.
The official USDA press release provides the basic facts, and Brad Plumer at Vox.com provides a more in-depth look at the history, background, and science behind this mass mortality event. You can also check out the regularly updated USFS California Tree Mortality site for photos, videos, and advice for California forest landowners.
Updated to add: This striking pictorial essay by the online magazine BioGraphic describes the impending mortality of California’s giant sequoias – once thought to be nearly impervious to environmental disturbances.