That has provoked a debate about whether the phenomenon is an aberration, or whether natural selection favours it, at least when it is rare in a population.
Firms responsible for emissions, including utilities and oil producers, would either have to cut them or compete to buy a steadily shrinking number of permits.
Thin trading made for a lackluster day on Wall Street, with desks short-staffed before the Memorial day holiday that will keep U. S. markets closed on Monday.
The method that measures organic thermal maturity directly from seismic information is of great value for areas with lower exploratory levels, especially for the basins with sparse welldrillings.
When it comes to putting a dollar value on Chinese works of art, a few things matter: a tie to the Imperial family, a solid provenance, condition, quality of the workmanship and rarity.
They looked at death rates by county, having corrected for migration and merged sparsely populated ones so that America's 3,141 counties became 2,068 "county units".
That is why the smallest of the herbivores, Thomson's gazelle, lives on fruit that is very nutritious but too thin on the ground to support a larger animal.
Toward the top (northern) end of the image, the ice becomes sparser, but the walls of a large impact crater in the upper-left corner provide a refuge for an oblong ice deposit on the crater floor.