BARCELONA (EFE) .- The lack of rain advances spring in the northern hemisphere because with less cloudiness, day and night temperatures have more contrast, there is more solar radiation and more frost, factors that make plants confused and consider that spring has come.
This is confirmed by a study published today by the journal ‘Nature Climate Change’ and led by researchers Jian Wang, from the Ohio State University in the USA, and Josep Peñuelas, CSIC research professor at CREAF in Barcelona (northeast Spain). , which confirmed that the lack of rain expected this century can advance spring by between 1.2 and 2.2 days per decade.
Science shows that climate change is advancing phenological spring, but until now mild winters caused by global warming were thought to be the main cause.
However, this new work shows that the lack of rain also causes plants to sprout earlier in the northern hemisphere, where rainfall has decreased in frequency in the last thirty years and this affected the natural calendar of plants.
The research relates for the first time the lack of rain and the premature awakening of nature, specifically it foresees an additional advance of the biological spring of between 1.2 and 2.2 days per decade as a consequence only of the decrease in the frequency of the rainfall forecast for this century.
“Less precipitation means less cloud cover, which gives more hours of sunshine, higher midday temperatures, and cooler nights that advance the cold buildup required for leaves to sprout. The cocktail of conditions confuses plants and causes them to sprout.” before,” explains Peñuelas.
“This winter we are experiencing a paradigmatic situation to understand the results of this article. It doesn’t rain and we have frosts and strong contrasts that have clearly advanced spring,” adds the CREAF researcher.
To carry out the study, the researchers measured the carbon fluxes of the vegetation, since when the plants wake up they start photosynthesis and change the carbon fluxes, they recorded the output of the leaves ‘in situ’ and verified on a large scale with satellite images the changes in the greenness of the vegetation.
Peñuelas’ explanation is as follows: “If the winters have less and less rain, this means that there are fewer clouds. The clear skies give strong temperature contrasts between day and night, and the daytime temperature also rises much higher “.
“In the same way, without the cloud cover filter, plants receive solar radiation for many more hours. At night, conversely, the environment cools quickly and freezes easily. All this confuses plants because they perceive it as signals typical that spring has already arrived: they accumulate the hours of cold and radiation they need earlier and, together with the temperature contrasts typical of spring, they wake up from their winter slumber before time”, summarizes the scientist.
In addition, according to Peñuelas, “if the plants sprout earlier, they begin to photosynthesize earlier and this affects the carbon cycles around the world. Knowing that the decrease in the frequency of rainfall also affects this natural rhythm is key knowledge to take into account in climate change predictions”.
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