Is climate change real?

Climate change is real — I'll gather the latest scientific evidence to show why.

Yes, according to the overwhelming body of scientific evidence and the assessment of major scientific organizations, climate change is real and is occurring at an unprecedented rate.

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

Scientific Consensus

There is overwhelming scientific evidence that the Earth is warming and that human activities, especially the emission of greenhouse gases, are the primary cause

Multiple large-scale assessments, including those by the Intergovernmental Panel on Climate Change (IPCC), have established a strong consensus among climate scientists that global warming is real and largely human-induced.

•The IPCC's Sixth Assessment concluded that human activities have unequivocally caused global warming

•A United Nations IPCC 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

•The report draws from many independent scientific analyses of climate change, which use direct observations of Earth’s climate, paleoclimate archives, theoretical studies and simulations

Estimates of that consensus vary by method:

•Taken together, the evidence indicates that an overwhelming majority of climate scientists agree recent climate change is primarily caused by human emissions; most commonly cited figures are ~97% among publishing climate experts, and literature-only analyses have found agreement exceeding 99%

•A 2019 review of scientific papers found the consensus on the cause of climate change to be at 100% and a 2021 study concluded that over 99% of scientific papers agree on the human cause

Joint statement by International Academies:

> "Climate change is real. There will always be uncertainty in understanding a system as complex as the world’s climate. However there is now strong evidence that significant global warming is occurring. The evidence comes from direct measurements of rising surface air temperatures and subsurface ocean temperatures and from phenomena such as increases in average global sea levels, retreating glaciers, and changes to many physical and biological systems

Key Lines of Evidence

1.Rising Temperatures: While natural variability plays some part, the preponderance of evidence indicates that human activities—particularly emissions of heat-trapping greenhouse gases—are mostly responsible. According to analysis led by scientists at NASA's Goddard Institute for Space Studies (GISS), the average global temperature on Earth has increased by at least 1.1° Celsius (1.9° Fahrenheit) since 1880. The IPCC estimated average global surface temperature during 2011–2020 at about 1.1°C above the 1850–1900 baseline.

2.Greenhouse Gases: Today carbon dioxide is at an "unprecedented" level not seen for at least the last 800,000 years.

3.Ice and Ocean Changes: There is "high confidence" that over the last two decades the Greenland and Antarctic ice sheets have been melting, glaciers have receded in most parts of the world, and Arctic sea ice has continued to shrink. Other observed changes include rising ocean temperatures, accelerating melting of polar ice sheets, and sea-level rise.

4.Multiple Independent Indicators: Evidence of warming comes from warming of the climate system as evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising sea level.

No major scientific organization that studies climate maintains that the observed warming is not real or is entirely natural. The debate in the scientific literature is not about whether climate change is happening, but about details of its impacts, regional patterns, and future projections under different emission scenarios.

Citations (2)

1nasa.govGovernment
Climate Change - NASA Science
Backs: “There is unequivocal evidence that Earth is warming at an unprecedented rate.”
2nasa.govGovernment
New U.N. report: Humans responsible for climate change - NASA Science
Backs: “The IPCC's Sixth Assessment concluded that human activities have unequivocally caused global warming. A United Nations IPCC 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”