Quick Answer
A global desertification event would remove huge amounts of vegetation and freshwater availability. Dust would increase, agriculture would collapse in many regions, and societies would concentrate around remaining rivers, lakes and reliable groundwater. The climate response would vary by region because vegetation, clouds, soil and atmospheric circulation all interact.
A desert is not just sand
Deserts are defined primarily by low precipitation, not by endless dunes. A planet-wide shift toward aridity would therefore produce rocky deserts, dry grasslands, salt flats and extremely sparse landscapes as well as sandy regions.
Freshwater becomes the limiting resource
Rivers and lakes depend on precipitation, snowmelt and groundwater recharge. If rainfall declined across most land, many rivers would become seasonal or disappear. Aquifers would be drawn down faster than they could naturally recover, turning reliable water access into the central constraint on settlement.
Food production would be hit first
Modern agriculture depends heavily on predictable water. Rain-fed farming would contract dramatically, while irrigation would become possible only where rivers, reservoirs or groundwater remained available. Crop production would increasingly concentrate in a smaller number of unusually wet regions.
Established scienceVegetation strongly influences the water cycle by moving water from soil to atmosphere through evapotranspiration. Removing vegetation can therefore reinforce local drying, although the strength of this feedback varies by climate and region.
What happens to wildlife?
Species adapted to forests, wetlands and humid grasslands would lose habitat. Desert specialists could expand, but only where temperatures and food webs remain suitable. The transition would cause a major extinction pressure because ecosystems cannot instantly evolve into new forms.
Dust changes the atmosphere
Bare soils are easier for wind to erode. More airborne dust would affect air quality and could alter cloud formation and sunlight absorption. Dust transported across oceans can also deliver nutrients, so the ecological effects would extend beyond the deserts themselves.
Civilization would reorganize
Large populations would cluster around surviving water sources. Food imports, desalination, water recycling and long-distance pipelines would become strategically important. Regions unable to secure reliable water could experience large-scale migration.
The bottom line
A desert Earth would not simply be a hotter version of today's world. It would be a planet with a radically different water cycle, much less terrestrial biomass and a civilization organized around the remaining sources of fresh water.
A note on our approach: Every article on WhatIfLab separates what current science establishes from what remains genuinely speculative. Where we cite a figure or finding, it reflects published, mainstream research at the time of writing — not a prediction dressed up as fact.