The warming of the global atmosphere over time is well known, although individual areas of the globe vary in what they are experiencing. Humidity is another variable that is changing, but in harder to discern ways. We know that as air temperature increases, it has the potential to hold more water vapor. But according to measurements, humidity is not increasing in most areas, and in some areas is getting lower. This has important consequences for what the future climate might be like, since humidity affects clouds and precipitation. It also can affect growing conditions for plants and plant diseases. This article from Carbon Brief describes some of the issues with humidity, including measurement errors and impacts on the water balance.
