Complexities ...

... keep scientists on their toes (metaphorically speaking).

The alkaline soil of Gubantonggut [China's Gubantonggut Desert] is socking away large quantities of CO₂ in an inorganic form.

and

Halfway around the world, researchers have found that Nevada's Mojave Desert, square meter for square meter, absorbs about the same amount of CO₂ as some temperate forests. The two sets of findings suggest that deserts are unsung players in the global carbon cycle.