Identifying the culprits of global warming since pre-industrial times
Research published in the journal ‘Scientific Data’ offers new insight on countries’ contributions to global warming caused by CO2, methane (CH4) and nitrous oxide (N2O) emissions between 1851 and 2021. Supported by the EU-funded VERIFY, 4C, PARIS REINFORCE and ESM2025 projects, this work could help inform national commitments to decarbonisation. The study shows how global mean surface temperature has responded to CO2, CH4 and N2O emissions since the pre-industrial period. It also reveals national contributions to global warming from emissions of each of the three greenhouse gases, including those from the fossil fuel and land use sectors. According to the findings, the largest contributor to warming since 1850 through emissions of all three gases was the United States. This country has been responsible for a 0.28 °C increase in temperatures, or 17.3 % of warming induced by global emissions of the three gases. The United States was followed by China (0.20 °C, corresponding to 12.3 %), Russia (0.10 °C, 6.1 %), Brazil (0.08 °C, 4.9 %), India (0.08 °C, 4.8 %), and Canada, Germany, Indonesia, Japan and the United Kingdom (each contributing 0.03–0.05 °C).
The biggest gaseous culprit
CO2 has been the largest contributor to global warming, responsible for 69.1 % of the total warming caused by the three gases. It has also resulted in a 1.11 °C temperature rise up to 2021, compared to the 0.41 °C and 0.08 °C warming caused by CH4 and N2O emissions, respectively. “This new dataset will prove a critical tool for tracking the effect of changing national emissions on warming, for example as a result of climate policies implemented since the Paris Agreement,” states the study’s first author Dr Matthew Jones of VERIFY and 4C project partner University of East Anglia, United Kingdom, in an article on the university’s website. “During the coming years, we hope to see the warming contributions by all countries level off, with no new additions to warming year-on-year, as commitments to reach net-zero emissions are met or surpassed.” Countries’ contributions to warming relative to others’ have changed over time. Russia was the second largest contributor before being overtaken by China in 1992. Likewise, Indonesia has overtaken both Germany and the United Kingdom to rank sixth. “Notably, the combined contributions to warming from Brazil, South Africa, India and China rose from 17% in 1992 to 23% in 2021, whereas the contribution from the industrialised OECD countries fell slightly from 47% to 40%,” notes Dr Jones. “These examples illustrate how the contributions to global warming from industrialising nations are rising as their emissions grow relative to early-industrialisers, many of which have begun to decarbonise.” Although some countries’ emissions are still mostly linked to deforestation and agricultural expansion, fossil emissions have overtaken land use emissions in most countries in the last few decades. “Since 1992, the additional warming caused by global fossil fuel emissions has been over four times greater than the additional warming caused by land use change,” explains Dr Jones. The data set created with support from VERIFY (Observation-based system for monitoring and verification of greenhouse gases), 4C (Climate-Carbon Interactions in the Current Century), PARIS REINFORCE (Delivering on the Paris Agreement: A demand-driven, integrated assessment modelling approach) and ESM2025 (Earth system models for the future) “is uniquely positioned to informing climate policy and benchmarking,” concludes the researcher. For more information, please see: VERIFY project website 4C project website PARIS REINFORCE project website ESM2025 project website
Keywords
VERIFY, 4C, PARIS REINFORCE, ESM2025, climate change, warming, emissions, greenhouse gas, CO2, methane, nitrous oxide, CH4, N2O
