Top contributors to greenhouse gas emissions in the context of "Hydrochlorofluorocarbon"

Greenhouse gas (GHG) emissions from human activities intensify the greenhouse effect. This contributes to climate change. Carbon dioxide (CO₂), from burning fossil fuels such as coal, oil, and natural gas, is the main cause of climate change. The largest annual emissions are from China followed by the United States. The United States has higher emissions per capita. The main producers fueling the emissions globally are large oil and gas companies. Emissions from human activities have increased atmospheric carbon dioxide by about 50% over pre-industrial levels. The growing levels of emissions have varied, but have been consistent among all greenhouse gases. Emissions in the 2010s averaged 56 billion tons a year, higher than any decade before. Total cumulative emissions from 1870 to 2022 were 703 GtC (2575 GtCO₂), of which 484±20 GtC (1773±73 GtCO₂) from fossil fuels and industry, and 219±60 GtC (802±220 GtCO₂) from land use change. Land-use change, such as deforestation, caused about 31% of cumulative emissions over 1870–2022, coal 32%, oil 24%, and gas 10%.

Carbon dioxide is the main greenhouse gas resulting from human activities. It accounts for more than half of warming. Methane (CH₄) emissions have almost the same short-term impact. Nitrous oxide (N₂O) and fluorinated gases (F-gases) play a lesser role in comparison. Emissions of carbon dioxide, methane and nitrous oxide in 2023 were all higher than ever before.

Shell plc is a British multinational oil and gas company, headquartered in London, United Kingdom. Shell is a public limited company with a primary listing on the London Stock Exchange (LSE) and secondary listings on Euronext Amsterdam and the New York Stock Exchange. A core component of Big Oil, Shell is the second largest investor-owned oil and gas company in the world by revenue (after ExxonMobil), and among the world's largest companies out of any industry. Measured by both its own emissions, and the emissions of all the fossil fuels it sells, Shell was the ninth-largest corporate producer of greenhouse gas emissions in the period 1988–2015.

Shell was formed in April 1907 through the merger of Royal Dutch Petroleum Company of the Netherlands and The "Shell" Transport and Trading Company of the United Kingdom. The combined company rapidly became the leading competitor of the American Standard Oil and by 1920 Shell was the largest producer of oil in the world. Shell first entered the chemicals industry in 1929. Shell was one of the "Seven Sisters" which dominated the global petroleum industry from the mid-1940s to the mid-1970s. In 1964, Shell was a partner in the world's first commercial sea transportation of liquefied natural gas (LNG). In 1970, Shell acquired the mining company Billiton, which it subsequently sold in 1994 and now forms part of BHP. In recent decades gas has become an increasingly important part of Shell's business and Shell acquired BG Group in 2016.