Spring arriving earlier due to global warming

Spring is arriving ever earlier as greenhouse gas emissions and global temperatures rise, and the northern hemisphere growing season is now two weeks longer than it was in 1900. But paradoxically, new research shows that forest giants that once responded to the early spring are beginning to slow down – because they miss the chill.

Yongshuo Fu, an earth system scientist at Peking University, Beijing, and colleagues report in Nature journal that they have measured a slowdown in the response of oaks and other forest citizens to the change in temperatures and carbon dioxide levels. Where these species, on average, unfolded their first leaves four days earlier, with every 1˚C rise in temperature, they now do so only 2.3 days earlier, according to Climate News Network news received from London yesterday.

The reason is that, to take full advantage of the ever-earlier spring, these deciduous species first need to feel a period of chill. And as temperatures on average rise, the extent of true winter chill diminishes.

The scientists used direct observation, and confirmed their hypothesis with computer models to show once again that as humans change the climate, by increasing carbon dioxide levels in the atmosphere as a consequence of the combustion of fossil fuels, they are also changing the ecosystems that support all life on earth.

And in the same week, US scientists report that as global warming begins to change the mix of mountain wildflowers each spring, pollinating insects too are beginning to respond.  The research confirms a wider picture of change as a consequence of global warming. In the Americas, plants are colonising higher slopes, and in Europe the bumblebee has also been feeling the heat, and losing part of its range.

Source

http://www.thedailystar.net/city/spring-arriving-earlier-due-global-warming-152086