Scientists say that warmer air holds more moisture, producing both more drought and more extreme rainfall. A paper published last year in Nature Reviews likened the atmosphere to a sponge that is growing larger as the planet warms. A bigger sponge soaks up more moisture from plants, soils, lakes, and rivers, creating drier conditions on the ground… ‘VPD, or Vapor Pressure Deficit, is a measure of the difference between the amount of moisture in the air and the amount it could hold when fully saturated (100% humidity). Cooler air can hold less moisture, so it doesn't require plants to release much water. Warmer air, however, can hold more moisture, which means it puts more demand for moisture on plants (figure 1).’ For example, figure 2 shows what happens to VPD during extreme heat waves. If the relative humidity stays at 20% (red dotted line) and the temperature goes up by 40%, i.e. 10°C, the VPD increases by 80%, i.e. 2.0 kPa (red arrows).(for every +1°C 7-8%) vpdrought.wsl.ch/en/what-is-… what is VPD