I have a degree in physics, so I can explain global warming.
The sun is constantly bombarding the earth with massive amounts of solar energy.
But the problem is that when it hits the earth, it is absorbed as heat and builds up, moving around inside the atmosphere, by conduction and convection.
What determines how much heat builds up depend on the outer layer of the atmosphere.
That boundary layer is extremely important because no heat can escape to space because there can be no conduction or convection to the vacuum of space.
It can only leave by returning to the form of photonic radiation.
And the problem is that carbon prevents photonic radiation, but changes it back in to vibratory heat again, so it is trapped.
So the amount of carbon at the outer atmosphere boundary layer to space, is what determines planetary heat retention or not.
There is no question that we have increased atmospheric carbon, through CO2, by almost 40%.
Since the scale starts at 200 ppm, because is has never been lower than 200, the graph looks like it almost tripled.
But I don't want to try to give that false impression. The increase from 250 to 400 is not triple but is almost double.
So that means we are not just retaining more heat, but it is accumulative, and we are also constantly increasing the carbon as well.
So even if we stopped increasing CO2 today, the increase of heat accumulation would continue for hundreds of years to come, possibly making the planet unlivable.
This has never happened before, so it is hard to predict.
How could this happen?
Because fossil fuel is hundreds of millions of years worth of concentrated solar energy.
We release tens of millions of years worth of sequestered fossil sunlight every year that we burn as much fossil fuel as we are burning.
Does that make it easier to understand why smart people are worried?
Let me know if there is more you want me to detail?