The early arrival of spring is often cause for celebration in northern climates. But it may come at the cost of drier, hotter days in some areas in summer.
As winter wanes and leaves start to peek out from branches, trees increasingly draw water from the soil and move it into the sky — a process known as evapotranspiration. But when this greening starts earlier in the calendar year, scientists worry that more moisture could be sucked from the soil than if the season starts later.
Now, analyses of satellite data and climate simulations show that earlier spring greening can leave soils drier in summer across much of the Northern Hemisphere. That, in turn, could lead to more frequent and intense summer heat waves, researchers report January 3 in Science Advances.
As the climate warms, scientists expect to see earlier springs and longer growing seasons. One study found that, already, the growing season in the Northern Hemisphere has been extended by about 10 days on average over the last three decades.