Spring in many places is late

As the earth gets warmer, it is common for plants to sprout earlier. But the truth is not so simple, about 30% of North America is picking up the spring later, there is a late place up to 3 weeks compared to 1982. While in most of the upper part of North America, the trees are greening again. sooner, there are places over 3 weeks, then the lower part of North America is the opposite.

"It is really surprising," Xiaoyang Zhang from the Institute of Earth Resources Technology in Maryland, USA, said, because previous studies often show that plants will budge earlier than fruit. warm up soil.

"Nobody realizes that warming can slow down the process of changing the leaves of spring".

Zhang discovered this abnormality when examining satellite images showing how the color of vegetation changes seasonally throughout the United States, from 1982 to 2005. On the 40th parallel North, trees bloom The average leaves 0.32 days earlier each year during the above period. But below 31 degrees North, the average sprouting plant was 0.15 days later. The only thing that climate change does not cause, is 35 degrees North.

The same model also appeared when Zhang checked the data on when lilacs bloom each year.

Zhang said that some plants need to be exposed to a short cold spell to sprout. Plants in the northern highlands still have this cold wave, but not with trees below 35 degrees north latitude, it does not make them grow later when the earth warms.

In some areas, the spring comes earlier (the band turns green) while others are late (reddening). - (Photo: Xiaoyang Zhang)

Thuan An