Scientific American - Plants flowering later on the Tibetan plateau: Shorter growing season linked to warmer winters on 'The Roof of the World'

In many regions, climate change has advanced the timing of spring events, such as flowering or the unfolding of leaves. But the meadows and steppes of the Tibetan Plateau are bucking that trend -- plants are starting to bloom later in spring, making the growing season shorter. This change could threaten the livelihood of the thousands of nomads who survive by raising cattle on the plateau.

Martin Lechowicz, a plant ecologist at McGill University is not surprised, however. Lechowicz and his colleagues have analysed and modelled the timing of leaf-bud burst in 22 North American tree species throughout the twenty-first century. Almost all species showed earlier bud burst, but some had years of abnormal bud-burst timing because they had not chilled enough over the winter.

"Many models of climate change's effects on the growing season don't deal with the internal climate-control system by which plants respond to seasonal temperature changes," says Lechowicz.