Global warming is real, the cause is not.

Past periods of climate change have taken tens of thousands of years to rise a single degree. What happened in the 19th and 20th century that suddenly caused the rate of change to accelerate from one degree in ten thousand years to one degree per century?

Changes to solar output cycle over a period of eleven years on average, so while solar output can cause very short term changes to climate, it only lasts for a few years before reversing. Over tens of millions of years, the sun has warmed, and it will eventually cool, but that takes millions of years to have an effect.

Changes to the earth's orbit is a bit faster: that only takes tens of thousands of years.

Volcanoes occur randomly and don't lead to a trend of global warming: volcanoes cause cooling that might last a few years or a decade.

So if it is not human activity (cutting down forests, building cities, burning trillions of tonnes of oil and gas a year) that is causing the current rapid rise in temperatures (1 degree per century since the start of the industrial revolution; about 2 degrees per century now) what is it?