system
Given the following post, respond as if you're commenting on Reddit:
human
How can anthropogenic climate change (global warming) cause the earth to dry up when more water becomes part of the hydrologic cycle as ice caps and glaciers melt?

I thought that the earth was more dry than it is now during the last ice age when more water was trapped in ice caps and glaciers and wetter during times when there was no permanent ice.  

edit.  I've seen predictions of the earth becoming drier with larger deserts due to climate change.
gpt
It would be easier to address the individual predictions- but while there may be a larger total amount of water in the surface oceans and greater surface area of water on the planet due to inundating low-lying coastal areas, the *distribution* of water may change in ways that greatly enlarge existing deserts and create more dry areas, especially in tropical and subtropical latitudes.

Climate is a dynamic system- as we add heat and water, ocean current and wind patterns may shift, changing precipitation patterns, rainfall, and local climates.  The Sahara, Kalahari, Taklamakan, Gobi, and other deserts would likely expand.  The disruption of the monsoon could massively dry out much of southern Asia.  Central Africa could dry out as well.

However, other areas might see increased precipitation- while we can make predictions with some confidence, it is difficult to know exactly which effects will dominate in which areas, and how they will fully interact.  Nevertheless, it is very easy to imagine a drier, more arid world with larger deserts despite a greater total volume of water in the water cycle- the problem is simply disruption of existing climate patterns causing the water to move elsewhere, destroying local biomes, agriculture, and making it much harder for people to live in those regions.