Moorland occurs as a habitat type across tropical Africa, northern and western Europe and South America rather than as one bounded place; this atlas's own cited Wikipedia article states only that Great Britain holds an estimated 10 to 15 percent of the world's moors, a proportion that itself implies no global total is stated anywhere in the article, since the figure is given as a share rather than alongside an absolute worldwide total.
What would resolve this A single authoritative global inventory of moorland extent across every region where it occurs, under one consistent definition distinguishing moorland from heath and from tundra.
OpenPhysical geography / vegetation ecologyMoorland (Wikipedia)