I suggest everyone get the four "G"s, and hunker down for some Mad Max action, Guns, Grain, Ground and Gold. Some oil stocks would be nice as the USD$ is in its death throws. Anyhow, peak oil is here and western civilazation will collapse, so lock and load. Start your garden now and get some goats (if you still want to have goat chesse, which I love). Learn to barter, and something with which to barter with (other than manipulating a computer).

I put the polar bear and polar ice discussion into the context of a planet that will see tremendous changes in the 21st century – oil slowly declining in availability, temperatures rising, and food and water shortages that have already started in many parts of the world. All of these current or projected events seem to point to two required actions by people: 1) walk lightly – use less, conserve more, live smarter, and 2) reduce population to a long-term maintainable level, which will reduce greenhouse gas production, pollution, and stress on food and water sources.

These are both big challenges to implement in the USA, let alone globally. But all it would of course help the polar bears and other endangered species, and our own civilization and survival. That is the big picture of environment, as I see it.

Thanks for your comment.

Contaminants are definitely a concern for polar bears and other animals (including people!). The USGS report does consider other factors besides sea ice, although sea ice extent and ice-free days are the primary focus.

The authors found significant relationships between sea ice cover and several measures of polar bear nutritional status and population dynamics (such as mass, growth, and cub recruitment). For example, in the Southern Beaufort Sea, the bear population starts to decline when there are more than 125 consecutive ice-free days.

Could contaminants play a role in current declines in polar bear numbers? Certainly the report does not rule out this possibility, and I’m sure that future research will explore the effects of contaminants on population size.

However, one interesting result in the report was that in the Southern Beaufort Sea, polar bears are declining even though these bears have lower contaminant levels than other populations (some of which are currently stable). Also, a 2005 study found that in polar bears from Svalbard, Greenland, Canada and Alaska, tissue concentrations of many contaminants have actually decreased over time.

Of course this isn’t to say we shouldn’t be concerned about or try to decrease contaminant levels! Just that the data so far point to sea ice dynamics as a critical factor for today’s polar bears – and one that will become increasingly important in the future.

Hope that helps.

cheers,
Lisa

How can we be sure that we've not decreased the productivity of polar bears via estrogenic pesticides, dioxins and PCB's?

http://nsidc.org/news/press/2007_seaiceminimum/20070810_index.html

From the site:
"All of this leads us to ask: why has the melt season progressed so quickly? The answer lies in a combination of high temperatures, changes in the age and thickness of ice, and fluctuations in atmospheric circulations." (My coment as a former meteorologist:record number of clear days because of the upper wind pattern being stuck as a ridge of high pressure over that area.)

There's also the fact of all the soot making the snow fields dirty and darker, thus obsorbing more heating sunlight instead of refecting it (per another post by a Environmental Defense author a few weeks ago).