Correct option is D
Introduction
Desertification is the persistent degradation of dryland ecosystems through climatic variation and human activities, reducing biological productivity.
It has significant implications for soil carbon, land use, and the global climate system.
Information Booster
This is false because desertification actually releases stored soil carbon rather than keeping it intact.
As vegetation is lost and soils degrade, the organic carbon held in dryland soils is oxidised and emitted to the atmosphere as CO₂, making desertification a net source of greenhouse gases and a contributor to the greenhouse effect.
Drylands cover roughly 40% of the Earth's land surface and store a substantial fraction of global soil carbon; when they degrade, this carbon pool is depleted, reducing the land's carbon-sequestration capacity and amplifying climate change.
The claim that degraded drylands leave carbon "intact" and therefore make no contribution to the greenhouse effect reverses the established science, making statement (d) the incorrect one and hence the answer.
Additional knowledge
Desertification caused by converting semi-arid land to dryland crop production (e.g., US Dust Bowl) — Correct. The 1930s Dust Bowl is the classic example, where over-cultivation of semi-arid grasslands stripped protective vegetation, leaving soils vulnerable to wind erosion and severe degradation.
· Desertification takes place within dryland regions in a mosaic pattern rather than at the margins — Correct. Contrary to the popular image of deserts "advancing" at their edges, degradation appears as scattered patches within drylands wherever land use and stress concentrate, forming a mosaic.
· ( Salinization through irrigation and destruction of riparian ecosystems through water diversion can cause desertification — Correct. Poor irrigation causes salt accumulation that renders soils infertile, while diverting river water collapses riparian vegetation, both driving land degradation.
English
10 Questions
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