When I wrote a long story about the retreat of sea ice, I made clear it could go the other way for a while, and that doesn't mean we don't know that a warmer world will have less sea ice. It just means there's a lot of variability and people can pay too much attention to the big swings in one direction or the other.

The responsibility of the scientist or journalist is to convey the context. If you're talking about the Arctic Sea ice, you have to embrace the reality that there's a huge number of other things that influence that on a year-to-year basis.

The survey of more than 100 waterways downstream from treatment plants and animal feedlots in 30 states found minute amounts of dozens of antibiotics, hormones, pain relievers, cough suppressants, disinfectants and other products. It is not known whether they are harmful to plants, animals or people. The findings were released yesterday on the Web site of the United States Geological Survey, which conducted the research, and in an online journal, Environmental Science and Technology.

Probably the single-most concrete and substantive thing an American, young American, could do to lower our carbon footprint is not turning off the lights or driving a Prius, it's having fewer kids...we'll soon see a market in baby-avoidance carbon credits similar to efforts to sell CO2 credits for avoiding deforestation.

There are still people who essentially live in intellectual silos and either read Mother Jones or watch Fox News, based on their worldview. And they pick information out that reinforces it rather than keeping an open mind.

The aspects of global warming that matter most to people - how rapidly will the seas rise? Are hurricanes already getting stronger? How strong will they get as a result of warming? Those are still immersed in complexity. So in those realms that catch people's attention most, or that get used as symbols by environmental campaigners, those facets really do come with significant back-and-forthing.

I'm trying mostly to ask questions. And not just trying to stake out a position on something, but also trying to define the stuff we agree on. I'm having battles with comment posters trying to insert a little sense of order so it's not just a long pissing match between the edges, which is what I think a lot of the blogosphere is tending to do.