Ridiculous topic of climate warming aside, an INCREASE of more than 100% simply means it more than doubled. A 100% increase of an original amount of 10 means that the number is now 20. A 150% increase of an original amount of 10 means that the number is now 25.
Yes, I understand that, but they aren't saying "Humans caused global warming to increase 123%" (from what I can tell), they are saying that humans are responsible for 123% of the global warming.