Is climate change real?

I'll gather the current science on whether climate change is happening.

Yes, climate change is real - according to the overwhelming scientific evidence and consensus.

What the science shows

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

NASA and other agencies summarize the evidence as:

> Earth-orbiting satellites and new technologies have helped scientists see the big picture, collecting many different types of information about our planet and its climate all over the world. These data, collected over many years, reveal the signs and patterns of a changing climate.

Key lines of evidence include:

1. Global temperature rise
> While natural variability plays some part, the preponderance of evidence indicates that human activities—particularly emissions of heat-trapping greenhouse gases—are mostly...
> the average global temperature on Earth has increased by at least 1.1° Celsius (1.9° Fahrenheit) since 1880. The majority of the warming has occurred since 1975, at a rate of roughly 0.15 to 0.20°C per decade.

Analysis of surface temperatures also shows:
> Air temperatures on Earth have been rising since the Industrial Revolution. While natural variability plays some part, the preponderance of evidence indicates that human activities—particularly emissions of heat-trapping greenhouse gases—are making our planet warmer

Even a small global average change is significant:
> A one-degree global change is significant because it takes a vast amount of heat to warm all of the oceans, the atmosphere, and the landmasses by that much.

2. Multiple independent indicators
The U.S. Climate Science Special Report notes:

> Trends in globally averaged temperature, sea level rise, upper-ocean heat content, land-based ice melt, arctic sea ice, depth of seasonal permafrost thaw, and other climate variables provide consistent evidence of a warming planet.

Other specific changes:

> Globally, sea level has risen about eight inches (20 centimeters) since the beginning of ... All signs suggest that this rise is accelerating.

> Global sea levels are rising as a result of human-caused global warming, with recent rates being unprecedented over the past 2,500-plus years.
> Sea level rise is caused primarily by two factors related to global warming: the added water from melting ice sheets and glaciers, and the expansion of seawater as it warms.

3. Human cause confirmed

> Many lines of evidence demonstrate that it is extremely likely that human influence has been the dominant cause of the observed ...
> Solar output changes and internal variability can only contribute marginally to the observed changes in climate over the last century

Scientific consensus

There is not significant disagreement among climate scientists:

> Yes, the vast majority of actively publishing climate scientists – 97 percent – agree that humans are causing global warming and climate change.

More recent reviews find even stronger agreement:

> 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 of climate change.

> The consensus that humans are causing recent global warming is shared by 90%–100% of publishing climate scientists according to six independent studies

And in the broader literature:

> In the scientific literature, there is a very strong consensus that global surface temperatures have increased in recent decades and that the trend is caused by human-induced

Major scientific organizations worldwide - including NASA, NOAA, the American Association for the Advancement of Science, the American Meteorological Society, the American Medical Association, and science academies of many nations - have issued statements supporting this consensus.

The Intergovernmental Panel on Climate Change (IPCC) - the United Nations body that assesses climate science from thousands of peer-reviewed studies - concluded in its 2021 Physical Science Basis report:

> It confirms that the climate is already changing in every region.
It considers in situ and remote observations; paleoclimate information; understanding of climate drivers and physical, chemical, and biological processes and feedbacks

What "climate change is real" means

In short: The planet is warming, sea levels and ocean heat are rising, ice is melting, and the evidence that human greenhouse gas emissions are the dominant driver is judged by scientists as unequivocal and extremely likely.