RAS question
Which assessment report of the IPCC introduced the concept of 'carbon budget'?
Correct answer: (D) Fifth Assessment Report.
The IPCC Fifth Assessment Report, released in 2013-14, introduced the carbon budget concept in IPCC reporting.
Explanation
The IPCC Fifth Assessment Report (AR5) introduced the carbon budget concept in IPCC reports. In carbon-budget framing, a carbon budget is the cumulative amount of carbon dioxide that can be emitted while still keeping global warming below a specified limit. AR5 linked a temperature target to a finite total quantity of permissible emissions, rather than treating emissions only as yearly flows. The Center for Climate and Energy Solutions explainer on the IPCC 1.5-degree report treats carbon budget as a key concept and places its first IPCC-report introduction in part of the Fifth Assessment Report in 2013.
Why the other options are wrong
- (A) The Sixth Assessment Report refined and used carbon-budget analysis, but the first IPCC-report introduction belongs to AR5.
- (B) The Third Assessment Report predates the formal introduction in AR5, so it is not the report credited with bringing the carbon-budget concept into IPCC reporting.
- (C) The Fourth Assessment Report developed climate science further, but it is not the report that first introduced carbon budget in IPCC reports.
Concept
Climate-change mitigation terminology under Environment and Ecology includes IPCC concepts. RAS repeatedly asks such IPCC concepts because they connect global climate science with policy targets and emissions accounting.