Are humans responsible for climate change?

I'll gather the latest evidence on human-caused climate change to answer your question.

Yes, according to the overwhelming scientific evidence and consensus, humans are responsible for modern climate change - as the principal or dominant cause of warming observed since the mid-20th century.

What the major scientific assessments say:

An earlier synthesis found: "based on extensive evidence, that it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century"

How humans cause warming:

Human activities - primarily burning fossil fuels (coal, oil, gas) for energy, transport and industry, plus deforestation and other land-use changes - emit greenhouse gases that trap heat.

The heat-trapping character of GHGs is a known physical property, and concentrations are now at an "unprecedented" level not seen for at least the last 800,000 years.

Why natural causes alone do not explain it:

Climate science distinguishes between natural drivers (solar activity, volcanic eruptions, internal variability) and human drivers.

Models that include only natural forcings cannot reproduce observed warming, while models that include human emissions do.

Scientific consensus:

In summary, while natural climate variability has always existed, the rapid warming since the 1950s, rising sea levels, melting ice sheets, and increase in greenhouse gases are unequivocally attributed by the IPCC, NASA, NOAA and other major scientific bodies to human activities, principally greenhouse gas emissions from burning fossil fuels.