Climate policy & equity
Historical Emissions
Definition
Historical emissions are the cumulative quantities of greenhouse gases — most often CO₂ from fossil fuels, industry, and land use — that a country or economy has released into the atmosphere since a reference point, conventionally 1850. Because CO₂ persists for centuries, cumulative emissions rather than annual flows determine each country's contribution to observed warming, and they underpin the UNFCCC principle of common but differentiated responsibilities.
References
cumulative shares and negotiation relevance
Overview
What it means
Today's developed economies account for the largest share of cumulative emissions since 1850, while low-income countries' share remains a few per cent — the arithmetic behind equity arguments for climate finance, loss and damage, and differentiated mitigation obligations.
At the same time, emissions growth now comes predominantly from developing economies, which complicates the narrative but not the stock of responsibility already in the atmosphere.
How it is used
Historical shares feature in UNFCCC negotiations, fair-share and carbon-budget analyses, climate-finance debates, and litigation.
Why it matters
Who caused the problem is a factual question with distributional consequences; historical emissions are how the world keeps score.