Are humans responsible for climate change?
I'll pull the latest scientific consensus on humanity's role in climate change.
Yes, according to the overwhelming scientific evidence and consensus, humans are the primary cause of recent climate change.
Scientific Consensus
unequivocal evidence that Earth is warming at an unprecedented rate. Human activity is the principal cause.the vast majority of actively publishing climate scientists – 97 percent – agree that humans are causing global warming and climate change.roughly 97% or higherThe Intergovernmental Panel on Climate Change (IPCC), the UN body for evaluating climate science with 195 member countries, provides the most authoritative assessments:
> "It is unequivocal that human influence has warmed the atmosphere, ocean, and land."
Its Sixth Assessment Report (AR6, 2021) reinforces earlier assessments that human activities are the primary driver of many of these observed changes.
The IPCC AR6 concludes it is unequivocal that humans have caused the earth’s climate to warm, with a likely human contribution of 0.8 to 1.3 degrees Celsius to global mean temperature since the late 1800s.
Previous assessment (AR5) found it was extremely likely (95-100% confidence) that human influence has been the dominant cause of the observed warming and in AR6 this language was strengthened to "unequivocal".
How Humans Cause Warming
Natural climate forcings include changes in the sun’s energy output, regular changes in Earth’s orbital cycle, and large volcanic eruptions. Human-caused forcings include emissions of heat-trapping gases (also known as greenhouse gases) and changes in land use
Observed increases in well-mixed greenhouse gas (GHG) concentrations since around 1750 are unequivocally caused by human activities.Yes, by increasing the abundance of greenhouse gases in the atmosphere, human activities are amplifying Earth’s natural greenhouse effect.Virtually all climate scientists agree that this increase in heat-trapping gases is the main reason for the 1.8°F (1.0°C) rise in global average temperature since the late nineteenth century.Carbon dioxide, methane, nitrous oxide, ozone, and various chlorofluorocarbonsIn the United States, most (about 74%) human-caused (anthropogenic) greenhouse gas (GHG) emissions come from burning fossil fuels—coal, natural gas, and petroleum—for energy use.
Attribution studies show the human link:
> Climate models run with only natural forcings (solar variability, volcanoes) cannot reproduce the observed 20th‑ and 21st‑century warming; models that include anthropogenic greenhouse‑gas and aerosol emissions do reproduce the warming
Are Natural Factors Also Involved?
Yes, climate has always varied naturally, but scientists state:
> Many lines of evidence demonstrate that human activities, especially emissions of greenhouse (heat-trapping) gases, are primarily responsible for recent observed climate change
> no other known climate influences have changed enough to account for the observed warming trend. Taken together, these and other lines of evidence point squarely to human activities as the cause of recent global warming
In summary, while natural variability, solar and volcanic activity play a small role, the rapid warming observed since the mid-20th century - about 1.1°C since 1850 - is unequivocally dominated by human emissions of greenhouse gases from burning fossil fuels, deforestation and other activities.
Citations (2)
- Climate Change - NASA Science
Backs: “There is unequivocal evidence that Earth is warming at an unprecedented rate.”
- Intergovernmental Panel on Climate Change: Sixth Assessment Report
Backs: “The Intergovernmental Panel on Climate Change (IPCC), the UN body for evaluating climate science with 195 member countries, provides the most authoritative assessments: "It is unequivocal that human influence has warmed the atmosphere, ocean, and land."”