We know that greenhouse gases keep the Earth warm. And we know that the concentration of greenhouse gases in the atmosphere is rising. So we can be very very confident, indeed practically certain, that the Earth as a whole is not going to cool as a result of humanity’s greenhouse gas emissions.
In other words, we know, almost certainly, that continuing to emit greenhouse gases will carry on causing global warming.
And we know enough to be certain that this will cause serious problems. [link to ‘Problems of a changing climate’]
But that’s not all we know. Scientific understanding can tell us lots more about the changes we should expect. For instance, we also know that land and sea have different heat capacities – so land warms up faster than sea. And high latitudes (regions closer to the poles than the equator) will warm up more than low latitudes.
So let’s say we manage to limit the global temperature increase to 2oC. Because of our understanding, we should expect greater warming over land masses, and even greater still over mid-to-high latitude land areas such as Europe, Russia, and the USA. This means that while it is good to try to limit the global temperature rise, we should not be fooled into thinking that the 2oC limit is somehow a ‘safe level’, or that it means the same thing for everyone.
[Videos: 1A, 2V]
[Add a pop-up box linked from ‘heat capacity’ in ‘But that’s not all we know’ para. Also add a page on why high latitudes will warm up more but how it is tricky to say how much and why obs don’t always match the theory because the theory is over interpreted e.g. the hiatus.]
This is defined as how much heat needs to be put into something, per kilo, for it to warm by a certain amount. If something has a low heat capacity, that means it takes less heat to warm it that amount. If its heat capacity is high, it takes more heat to get the same effecct. So technically land has a lower heat capacity than sea. Heat capacity also impacts how long something keeps its heat – something with a lower heat capacity will keep that heat less long than something with a higher heat capacity.