A couple of degrees ... does it matter?

2℃ of warming and we’re in heaps of trouble.

Almost as soon as you think about this proposition it sounds strange. After all, the biggest natural warming we all see occurs every year, when winter turns to summer. Most places, that’s a lot more than 2℃. So is the difference between day and night; or the coast and the inland. What is it about a bit of warming induced by human activity that makes experts so worried?

Here, I’ve updated a previous attempt to explain this. It’s actually both simple and complicated. The easy part is knowing that a human-induced greenhouse forcing never lets up - until we decide to fix it - so as long as it lasts, heat will be added to the Earth system until a new equilibrium surface temperature matches the planet’s new energy balance. The tricky part is understanding all the geophysical effects of the extra heat.

The essay is a bit long to put here; you can view or download the PDF by clicking the link opposite.

A COUPLE OF DEGREES ...

WHY IS IT A BIG DEAL?