First off I haven't read the paper in Science Express yet (I suspect you haven't either) and I don't have access here at home. If I have a chance I will access it at work. But I have two comments.

First, you left out the rest. From the same article:

Some climate-change deniers would say that this proves that mankind is not important in changing the climate. Climate change experts, like Dahl-Jensen, say it’s not so simple: The climate is always changing, sometimes very abruptly, so the last thing that mankind should be doing is adding its own forcing actions — like pumping unprecedented amounts of greenhouse gases into the atmosphere. Because you never know — you never know — what will tip the balance and send us hurdling into another abrupt change ... and into another era.

So whatever else this new data suggests, it doesn't negate what has been shown about AGW.

Now, compare an El Nino year with a La Nina year. The differences are quite extreme. These are localized (both in time and geography) changes that can be quite rapid. One controversial theory that applies to the same region (Greenland) is that mini ice ages and warming trends have occurred locally due to the breakdown and reappearance of the North Atlantic Current. This was the premise (hugely exaggerated) behind that carppy movie about climate change. So you are not talking about global changes but regional. That said, the 10 degrees in 50 years sounds dramatic and sounds faster than the end of the Medieval Warming and beginning of the mini-ice age, though I'd have to take a closer look at the data. And I suggest you do as well.

For what it's worth, I don't take the NYT as all that great on science. I have found major errors in their coverage of molecular biology (right down to once claiming RNA was the building block from which DNA was made, or some such nonsense). So I personally would need to judge from closer to the primary material. Which I will try to get to, work permitting.