Are humans responsible for climate change?

Yes, the overwhelming scientific consensus is that human activities are the primary driver of climate change observed since the mid-20th century. This conclusion is supported by multiple independent lines of evidence and is endorsed by virtually every major scientific organization in the world, including NASA, NOAA, the National Academies of Sciences, and the Intergovernmental Panel on Climate Change (IPCC).

Key points supporting this consensus:

Greenhouse gas emissions
Burning fossil fuels (coal, oil, and natural gas) releases carbon dioxide (CO₂) and other greenhouse gases into the atmosphere. These gases trap heat, creating a "greenhouse effect" that warms the planet. Atmospheric CO₂ levels have risen from about 280 parts per million (ppm) in pre-industrial times to over 420 ppm today—levels not seen in at least 800,000 years, based on ice core data.

Attribution studies
Climate scientists use sophisticated models to compare observed warming patterns with what would be expected from natural causes alone (like solar variation or volcanic activity) versus human-caused factors. These studies consistently show that natural factors alone cannot explain the rapid warming observed since the industrial revolution, especially the acceleration since the mid-20th century.

Other human activities
Beyond fossil fuel combustion, deforestation reduces the planet's capacity to absorb CO₂, industrial processes and agriculture release additional greenhouse gases like methane and nitrous oxide, and certain industrial chemicals contribute to warming as well.

Rate of change
While Earth's climate has changed naturally throughout its history, the current rate of warming—particularly over the past 50-100 years—is unusually fast and correlates strongly with the rise in human-caused greenhouse gas emissions.

Scientific consensus
Multiple studies analyzing thousands of peer-reviewed climate papers have found that the vast majority of climate scientists (often cited as 97% or higher) agree that human activities are the dominant cause of recent global warming.

This doesn't mean natural factors play no role in climate variability—they do, particularly on shorter timescales—but the scientific evidence strongly indicates that human activities are the main driver of the significant warming trend observed over the last century, and especially since 1950.