The total of sea ice is known as the sea ice extent.

VOA: special.2009.10.27

What they have found is that about 1, 800 protein-coding genes, some 7% of the total known, show signs of having been subject to recent natural selection.

ECONOMIST: Human evolution

Green aficionados are familiar with the statistic that the sun bathes the Earth in trillions of barrels of energy (in oil equivalent terms), and less familiar with the fact that total known hydrocarbon resources are also countable in the trillions of barrels (from the oil-sands and ultra-deep-water sub-salt fields, to methane hydrates and coal, not to mention shale gas).

FORBES: Steve Forbes Is Wrong

The new bodies bring the known total of Jupiter satellites to 39, of which 31 are irregulars.

BBC: More moons for Jupiter