Are humans responsible for climate change?

Yes, the overwhelming scientific consensus is that human activities are the primary driver of the climate change observed since the mid-20th century. Here's a summary of why:

Key Evidence

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.

Scientific consensus: Major scientific organizations worldwide—including NASA, NOAA, the Intergovernmental Panel on Climate Change (IPCC), and national academies of science from dozens of countries—agree that human activity is the dominant cause of recent warming. The IPCC's most recent assessments state it is "unequivocal" that human influence has warmed the atmosphere, ocean, and land.

Other human contributions:

Attribution science: Climate scientists use sophisticated models to distinguish human-caused warming from natural variability (like solar cycles or volcanic activity). These models consistently show that natural factors alone cannot explain the rapid warming trend observed since the Industrial Revolution, particularly the acceleration since the mid-20th century.

What This Means

While Earth's climate has always changed due to natural factors, the current rate and scale of warming is unusual and closely correlates with the rise in human-produced greenhouse gases. The scientific consensus on this point is about as strong as consensus gets in science—comparable to the consensus on evolution or the link between smoking and cancer.

If you'd like, I can search for more specific or recent data (e.g., current global temperature records, latest IPCC findings, or specific regional impacts).