Are humans responsible for climate change?

Humans' role in climate change is widely questioned — I'll pull the latest scientific consensus and evidence to answer.

Yes - according to the overwhelming scientific evidence and consensus, humans are responsible for the current warming and climate change.

Scientific Consensus

> There is unequivocal evidence that Earth is warming at an unprecedented rate. Human activity is the principal cause.

This statement is repeated across NASA's climate resources and .

Multiple independent efforts to quantify expert agreement show:

The scientific consensus is that the Earth's climate system is unequivocally warming, and that it is extremely likely (meaning 95% probability or higher) that this warming is predominantly caused by humans.

Evidence

> Scientists attribute the global warming trend observed since the mid-20th century to the human expansion of the "greenhouse effect" — warming that results when the atmosphere traps heat radiating from Earth toward space.

> Over the last century, burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2).

> The industrial activities that our modern civilization depends upon have raised atmospheric carbon dioxide levels by nearly 50% since 1750
This increase is due to human activities, because scientists can see a distinctive isotopic fingerprint in the atmosphere.

In its Sixth Assessment Report, the Intergovernmental Panel on Climate Change (IPCC) concluded that

> it is unequivocal 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.

A NASA study confirmed with direct observations:

> Climate modelling predicts that human activities are causing the release of greenhouse gases and aerosols that are ... Now, a NASA study has confirmed these predictions with direct observations for the first time: radiative forcings are increasing due to human actions, affecting the planet’s energy balance and ultimately causing climate change.

>It's direct evidence that human activities are causing changes to Earth's energy budget

While natural sources of climate variability are significant, multiple lines of evidence indicate that human influences have had an increasingly dominant effect on global climate warming observed since the mid-twentieth century.

In particular, current warming cannot be explained by the Sun:

> Since 1750, the average amount of energy from the Sun either remained constant or decreased slightly

> While the Sun has played a role in past climate changes, the evidence shows the current warming cannot be explained by the Sun.

In short, climate has varied naturally in the past, but the rapid warming since the mid-20th century - about 2.12°F (1.18°C) since the late 19th century with 10 of the warmest years observed since 2014 linked to human activities such as burning fossil fuels and clearing land - is predominantly human-caused.