This is true. That said, it's important to keep what 'historical norms' are in perspective as well. The time frame we are speaking of is smaller than a blip on the radar in terms of global climate. I'm not saying that we haven't played a role in warming things a bit (of course we have), but the big picture impact is likely overstated, and it might not even be a bad thing really anyway. We have no idea what the climate is going to be like in 2040, '50, whenever. Let's just say that we go through a stretch in a couple years where things freeze up nicely, 'like they used to'. This is entirely possible based on some projections that are about as meaningful as those saying we'll be ice free. Come the new decade, the new 30 year averages will be from 1991-2020. This will include the biggest years of the brief warm up. The next thing you know the observed trends will be a mirror opposite of what we were seeing earlier this decade, and it will look like an impending relative ice age. This is what happens when humans over emphasize their lifetime on a global scale.
Awareness is key of course. I'm not saying that you are being this way but some here are beating drums so loudly that they are unknowingly contributing to complacency.