Costs of Climate Change - Denial

 It's a VERY common refrain from the Climate Change Denial camp

"The climate has changed before.  It's always changing."

"How could CO2 cause climate change when it makes up less than 0.04% of the atmosphere?"

Both statements are true, up to a point.  It's what comes after that point that's the problem.

Both statements are addressed and debunked in this one article:

Opinion: Yes, there was global warming in prehistoric times. But nothing in millions of years compares with what we see today 

It's like this, briefly.

First, CO2 concentrations are higher now than they've been in the past 4 million years.  That encompasses the whole of human history and definitely the history of modern civilization.

That said, it's not the concentration of CO2 specifically OR the precise temperature that is the problem.  It's the RATE at which both CO2 and temperature are changing.

Yes, there have been warm periods in the Earth's past.  Those changes happed over thousands of years and amounted to around 0.1 degree F per century.  That's 10 times slower than the rate of change we're experiencing now.

What we're seeing now looks like this:

That rapid rate of change is what's giving us conditions like those shown in this data.  Where the past 12 months are the warmest they've ever been, historically.  A rate of change that's more like a whole degree in a decade (remember - 10 times faster than anything the Earth has experienced before).

The infrastructure on which 8 billion people depend - our cities, our agriculture, and pretty much everything else - was built around a climate that was stable for thousands of years.  Infrastructure can be adapted to changing conditions IF those changes happen slowly.  

They're not.