Here are the second five of my “Top 10 climate stories of 2006,” in no particular order. (The first five are here.)

2005 was hot: In early 2006, it was revealed that 2005 was a statistical tie with 1998 for the hottest year of the past 400. However, 1998 was warmed by the biggest El Nino of the 20th century, while 2005 had no such help. That means something else contributed to making 2005 so warm, and that something was almost certainly human activity. With a mild El Nino going on right now, my prediction is that 2007 will eclipse 1998 and 2005 as the hottest year of the instrumental record.

Arctic warming: Drowning polar bears, thawing permafrost, an ice-free Arctic — that’s the grim future depicted in the Arctic Climate Impact Assessment. Primarily because of the ice-albedo feedback, climate change has its greatest impact at high latitudes, which is already apparent in the Arctic. The report was widely covered when it came out, and helped move the debate from one about theoretical impacts to one about real, present-day changes.

The 2006 U.S. mid-term elections: This is a huge story for a number of reasons, but for the environment in general and climate in particular it was colossal. With Democrats taking over, look for a more climate-friendly climate in the House and Senate next year.

I’m mellltiiing!: No, not the Wicked Witch of the East … it’s Greenland. Until recently, the scientific community’s best guess was that increases in precipitation would compensate for increased melting for at least the next few decades, leading to little net change in the overall mass of Greenland. This was indeed the case for most of the 1990s. But recent measurements show melting greatly outstripping increased precipitation. Since Greenland contains enough water to raise sea level by about 20 feet, this is an extremely troubling result I’m sure we’ll hear more about.

And the biggest climate story of 2006:

No big scientific breakthroughs: Over the past five years, there have been virtually no breakthrough findings that revolutionized the science of climate change. There have been some tremendous scientific results, but they have largely confirmed what we already thought we knew: the climate is warming, humans are playing a role, and we can expect further warming of a few degrees Celsius if we don’t reduce our emissions of greenhouse gases.

The stability of the dominant climate-science paradigm should be both reassuring and unsettling: reassuring because it suggests we understand the climate pretty well; unsettling because it forecasts potentially serious impacts if we don’t take action soon.