What is causing global warming

1. The core mechanism: an intensified greenhouse effect

Greenhouse gases naturally keep Earth habitable by trapping some outgoing heat, but human emissions have increased the atmospheric concentration of these gases—CO2, methane, nitrous oxide and fluorinated gases—so that more solar energy is retained, shifting Earth’s radiative balance toward warming ^{[1] [3]}. Observational records and paleoclimate proxies show atmospheric CO2 and global temperatures rising together, and the rate of recent warming is far faster than typical post‑glacial changes, consistent with an anthropogenic greenhouse forcing ^{[1] [6]}.

2. The single largest source: burning fossil fuels

The combustion of coal, oil and natural gas for electricity, transport, industry and heating is the largest contributor to greenhouse gas emissions worldwide; the United Nations and national agencies quantify fossil fuels as roughly two‑thirds or more of global greenhouse emissions and the dominant source of added CO2 since the Industrial Revolution ^{[2] [7] [8]}. Scientific syntheses emphasize that reducing fossil fuel use is central to slowing future warming because each tonne of CO2 emitted adds to the cumulative atmospheric burden driving temperature rise ^{[3] [9]}.

3. Other human drivers: land use, agriculture and industrial gases

Deforestation and land‑use change both release stored carbon and reduce terrestrial carbon sinks, amplifying atmospheric CO2, while agricultural practices and fossil‑fuel‑related processes emit methane and nitrous oxide—potent greenhouse gases—and industry releases fluorinated gases with very high warming potency, making these sectors important secondary drivers of global warming ^{[6] [2] [3]}.

4. Why natural explanations fall short and the role of attribution

Analyses of solar output, volcanic activity and internal climate variability demonstrate that none of these natural factors changed enough to explain the observed warming since the mid‑20th century; climate attribution studies attribute nearly all of the recent global temperature increase to human influences, with well‑quantified ranges for contributions and some cooling offset from aerosols ^{[4] [5] [10]}. Independent datasets—satellites, ice cores, tree rings and instrumental records—converge on the conclusion that human‑caused greenhouse gas increases are the dominant explanation ^{[1] [10]}.

5. Stakes, uncertainties and competing narratives

The scientific consensus—documented by NASA, NOAA, the UN and national agencies—is unequivocal about the human role, yet public debate is shaped by political and economic interests: fossil fuel industries and aligned think tanks have historically sown doubt about causation to delay regulation, a tactic scholars compare to past industry misinformation campaigns ^[6]. Uncertainties remain about the precise timing and magnitude of regional impacts and potential climate “tipping points,” but these scientific uncertainties do not undermine the clear, evidence‑based link between human emissions and global warming ^{[9] [11]}.

6. What the evidence implies for action

Because atmospheric greenhouse gas concentrations are cumulative and largely controlled by human emissions, limiting future warming requires rapid and sustained emissions reductions—especially from fossil fuel combustion—alongside protecting and restoring carbon sinks and reducing non‑CO2 gases; major scientific and policy bodies argue that keeping warming near 1.5–2°C hinges on those collective measures ^{[2] [9] [12]}. If reporting or commentary omits the central role of human emissions, that omission risks misdirecting policy and public attention away from the sources that matter most ^{[7] [8]}.