> How do scientists know that recent climate change is largely caused by human activities?
> Scientists know that recent climate change is largely caused by human activities from an understanding of basic physics, comparing observations with models, and fingerprinting the detailed patterns of climate change caused by different human and natural influences.
> Climate is always changing. Why is climate change of concern now?
> All major climate changes, including natural ones, are disruptive. Past climate changes led to extinction of many species, population migrations, and pronounced changes in the land surface and ocean circulation. The speed of the current climate change is faster than most of the past events, making it more difficult for human societies and the natural world to adapt.
Technically correct I guess. Let us just say that the average temperature is rising from year to year. CO2 levels correlate very closely with this increase in temperature.
Let's say this correlation is not sufficient evidence and we know nothing about CO2 as a greenhouse gas. What would be the next best explanation?
If a volcano erupts and the lava is coming your way, are you going to stand still because the lava isn't man's fault?
To them, cutting down emissions might be as inefficient solution for climate change as it is for solving the lava problem.
It's another thing to work back from desired outcome to necessary facts and use it to deem those facts true, rather than testing if they are actually true.