Are humans driving climate change? I'll gather the latest scientific evidence on our role.
Yes, according to the overwhelming scientific evidence and consensus — although Earth's climate has also changed naturally in the past.
Scientific consensus is that humans are the dominant cause of modern climate change
•There is unequivocal evidence that Earth is warming at an unprecedented rate. Human activity is the principal cause.
•Using the scientific method, scientists have shown that humans are extremely likely the dominant cause of today's climate change.
•Multiple lines of evidence confirm that human activities are the primary cause of the global warming since the start of the 20th century. Natural factors, such as variations in the sun's output, volcanic activity, the Earth's orbit, the carbon cycle, and others, also affect Earth's radiative balance. However, beginning in the late 1700s, the net global effect of human activities has been a continual increase in greenhouse gas concentrations.
The Intergovernmental Panel on Climate Change (IPCC), which assesses the physical science of climate change from observations, paleoclimate archives and climate models, has stated this with increasing confidence over time:
•The AR5 concluded that ‘it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century’ (IPCC, 2013b).
•Similarly, the Summary for Policymakers of the IPCC Fifth Assessment Report states ‘it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.’
•The report says there is 95 percent certainty that humans have caused most of the warming of the planet's surface that has occurred since the 1950s, and that it is "extremely likely" that human activities have caused most of the warming of the planet's surface that has occurred since the 1950s.
•The IPCC reports in its foreword that “the IPCC is now 95 percent certain that humans are the main cause of current global warming.
•A later assessment concludes: It is unequivocal that human influence has warmed the atmosphere, ocean and land.
•The IPCC AR6 concludes that 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.
How wide is the agreement?
•Today, 97 percent to 99.9 percent of climate scientists agree that climate change is happening and that human activity is the primary cause.
•The same range is reported as: Today, 97% to 99.9% of climate scientists agree that climate change is happening and that human activity is the primary cause.
•Nearly all actively publishing climate scientists say humans are causing climate change.
What is the human mechanism?
Human activities are changing the natural greenhouse. Key contributions include:
•Human activities have contributed substantially to climate change through: Greenhouse Gas Emissions
•On Earth, human activities are changing the natural greenhouse. Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). To a lesser extent, the clearing of land for agriculture, industry, and other human activities has increased concentrations of greenhouse gases.
•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 chlorofluorocarbons are all human-emitted heat-trapping gases.
What about natural climate change?
Climate has changed naturally before the Industrial Revolution due to variations in sunlight, volcanic activity, and wobbles in Earth's orbit. But natural processes alone do not explain the current rapid change:
•While natural variability plays some part, the preponderance of evidence indicates that human activities—particularly emissions of heat-trapping greenhouse gases—are mostly responsible for making our planet warmer.
•Natural processes driving Earth's long-term climate variability do not explain the rapid climate change observed in recent decades. The only explanation that is consistent with all available evidence is that human impacts are playing an increasing role in climate change.
•Similarly: Natural processes driving Earth's long-term climate variability do not explain the rapid climate change observed in recent decades. The only explanation that is consistent with all available evidence is that human impacts are playing an increasing role in climate change.
In short, climate change is not exclusively caused by humans — natural factors still influence climate — but the rapid warming observed since the mid-20th century, and the unprecedented rate of greenhouse gas increase, is principally and overwhelmingly driven by human activities, primarily the burning of fossil fuels and land-use change.