Although studies abound that ensure that global warming will lead to droughts more severe, longer and more frequent, now there is also another investigation that does not quite agree with that theory. This is one jointly conducted by the University of California at Irvine and the University of Washington, and which has been published in the scientific journal Proceedings of the National Academy of Sciences (PNAS).
According to the authors, a high concentration of carbon dioxide allows plants to retain more water in the soil, so they can better adapt to high temperatures.
Until now, only atmospheric values (temperature, humidity, precipitation) were considered to assess droughts, as with the Palmer Drought Severity Index. With this index, it has been estimated that more than 70% will experience droughts if in one hundred years CO2 emissions are multiplied by four of the pre-industrial era. However, if information on water use by plants is incorporated, this value falls to 37%, why?
Carbon dioxide is vital for plants. Without it, they couldn't photosynthesize and they couldn't grow. To absorb it, they open structures that they have in the leaves called stomata, but this is a problem, as it lets moisture escape. Although the situation changes if there is a lot of CO2 present in the atmosphere since stomata don't need to be open as long, and as a consequence, the loss of water is less.
Still, if droughts occur during warmer times, they are fatal. Plants become weak, and in doing so pests kill them in a matter of very few days. Thus, although there are far fewer droughts, they can have serious consequences.
You can read the full study here (In English).