Is climate change real?

YesSays it is contested

Yes, climate change is real and well-documented by scientific evidence.

Here is what that means in scientific terms:

1. Climate has always changed, and is changing now:
Climate is defined as long-term average weather patterns over decades to centuries. Geological records show Earth's climate has changed many times due to natural factors like volcanic activity, variations in Earth's orbit, and solar changes.

Measurements show the climate is currently changing at a rapid rate:

•Global average surface temperature has risen about 1.1-1.2°C [2°F] since the late 19th century

•Ocean heat content has increased

•Global sea level has risen about 8-9 inches since 1880

•Arctic sea ice and glaciers have declined

•Atmospheric CO2 levels have increased from ~280 ppm pre-industrial to over 420 ppm today, as measured directly at observatories like Mauna Loa

2. What is causing the current change?
There are both natural and human factors that affect climate. According to major scientific organizations including NASA, NOAA, and the Intergovernmental Panel on Climate Change [IPCC], the dominant driver of warming since the mid-20th century is human activity.

The mechanism is the greenhouse effect: Gases like carbon dioxide, methane, and nitrous oxide trap heat in the atmosphere. Burning fossil fuels, deforestation, and industrial processes increase the concentration of these gases.

The IPCC's Sixth Assessment Report concluded it is "unequivocal that human influence has warmed the atmosphere, ocean and land."

3. Areas of scientific agreement and ongoing research:
There is very broad agreement among climate scientists that the climate is warming and human greenhouse gas emissions are the primary driver since the 1950s.

Ongoing scientific research focuses on questions like:

•Exactly how sensitive the climate is to greenhouse gases

•How quickly and severely specific impacts will unfold regionally

•The role of natural variability, clouds, and aerosols

•Projections for future warming under different emissions scenarios

While there is scientific consensus on the existence and human cause of recent warming, there is more debate among scientists, economists, and policymakers about the magnitude of future impacts and what the most effective policy responses should be.

Would you like an overview of the specific evidence for human-caused warming, or the evidence for natural climate variability?

Is climate change real?

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