The claim that climate change is caused primarily by human activities is true.
EPA, United States Environmental Protection Agency, makes the evaluation that “human activities have released large amounts of carbon dioxide and other greenhouse gases into the atmosphere”, and note that while “[natural] processes, such as…volcanic eruptions, also affect the earth’s climate…they do not explain the warming…over the last century” (https://www.epa.gov/climatechange-science/causes-climate-change). Through analysis of measures such as glacier lengths, ocean sediments, and the earth’s planetary orbit, EPA’s sources conclude that the increase in climate variation coincides with human activity post-Industrial Revolution and cannot be primarily or majorly accounted for by natural causes. One example is the increased concentration of greenhouse gases such as methane, carbon dioxide, and nitrous oxide (https://www.ipcc.ch/report/ar5/wg1/).
The site cites a Climate Science Special Report (CSSR), from the Fourth National Climate Assessment (https://science2017.globalchange.gov), and its findings are reiterated by Nasa’s Global Climate Change website (https://climate.nasa.gov/causes/), stating that “In its Sixth Assessment Report, the Intergovernmental Panel on Climate Change…concluded that…the increase of CO2, methane, and nitrous oxide in the atmosphere over the industrial era is the result of human activities and that human influence is the principal driver of many changes observed across the atmosphere, ocean, cryosphere and biosphere”.