What percentage of Earth's land is covered by trees?
488001
It`s about 45-50 % !\nBut If you realy means world as the earth !\nMay be there are more trees on the other unknown live planets !\nYou know 50 % is the percentage of 1990 and i guess that now in 2006 it should be 45 % , and sadly i should say if this tree termination method continues 1n 2025 you only can find tree in the museums !\nTry to hold them !\nTry to grow the trees !\nThey are our fathers !
418513
0.38 that of earth's\n\nhttp://www.amnh.org/rose/mars/pl2.html
15340
Earth has a surface area of 196,940,400 square miles, slightly less than a perfect ball with a diameter of 7913.5 miles The surface area of the seven continents and all the islands of the world is about 57 million miles, while the total area of the six habitable continents (Antarctica excluded) is around 52 million square miles. \n\nThe human population on earth has crossed six billion. If we distribute all the exposed land evenly among all mankind, 133 people would have to share one square mile. What that means is that every single person on Earth, man woman and child would have close to five acres of land for his or her use. More precisely, each person would get 209,000 square feet of land, or a square plot of land 457 feet on each side. \n\nNot all this land can be used beneficially however. A significant portion of the Earth's exposed land is unhabitable or cannot be used for any agricultural purpose. Large portions lie in the far north. Large portions are extremely arid. Large portions are very mountainous. In sum, only about one fourth of all the land on earth, or somewhat more than 12 million square miles, is arable. \n\nToday, over half of the arable land in the world is in fact not under cultivation. Bringing the unused land into service in many cases would require huge investments of money and effort, and would do considerable damage to the environment. For example, only about 28% of the arable land on the African continent is used for growing crops. Immense tracts of forests or jungles would have to be cleared to bring the rest of the arable land on that continent to productive use. \n\nThus, only about one eighth of each imaginary plot of land distributed to each person is land which is under cultivation. In effect, each person has a piece of land about 26,000 square feet (a square 161 feet on each side or just a bit more than ½ an acre) at his or her disposal on which to grow all that he or she needs.
627376
The only aswer to this is- grow more and more trees. Trees produce oxygen, it helps to increase rainfall, it helps to maintain temperture. so grow more and more trees and save earth.
824767
Approximately 61%\n\n#1 Asia - (3,879,000,000)\n#2 Africa - (877,500,000)\n#3 Europe - (727,000,000)\n#4 North America - (501,500,000)\n#5 South America - (379,500,000)\n#6 Australia/Oceania - (32,000,000)\n#7 Antarctica - (0)
454213
I have disagree with the first answer as 35% of the earth is Iron. And while Aluminum is more abundent on the surface, nearly 80% of the core is iron. So I have to go with Iron.
921300
Our beautiful earth is being destroyed. Thousands and thousands of trees are being cut down in short amounts of time, and trees give us the oxygen we need to survive. People are polluting the earth by littering, dumping trash into rivers, lakes and oceans. Car exhaust and smoking causes smog and makes the oxygen layer in our atmosphere thinner. If we don’t take action, our earth will end up like one big junkyard.
59626
The bigger problem is useable water.  Only 1% of earth's water can be used by humans.  The rest is salt water or glaciation.  Here's a good website explaining more:\n\nhttp://ga.water.usgs.gov/edu/earthwherewater.html
391671
Well, try to estimate ...\n\nCertainly, much-much-much-much less than even 2 to 549th power ... of course you cannot count, but you can make a very rough estimate.\n\nThe radius of Earth is roughly 6000-7000 km, so its surface area is ~ 10^8 km^2 = 10^16 cm^2\n\nNow go out in your back yard and count the average number of grass blades/cm^2 ... let's say you get 1/cm^2\n\nAs not all of the Earth is covered with grass, its unlikely that there are much more blades than 10^16. So 12900459358983340354 is definitely WRONG. But it's also unlikely that there are less than 10^13. Now I know that 10^16 is 1000 times greater than 10^13, but even with such rough estimates, we do know more than before doing these calculations, don't we?
1087611
More than 70% .        Of the whole earth's surface 80% is water. \nIt's too bad, 97.2% of all the water on earth is salt water though. \nNow, where do you think most salt water is found? That only leaves 2.8% is fresh water that we can drink or play in.
458236
Just the Jungles.\nNo land is free in this world.\nThanks to USA.
449917
Water Systems:\n\nhttp://www.ec.gc.ca/water/images/nature/prop/a2f2e.jpg\n\n95% of Earth's water is Salt Water leaving 5% as Fresh Water.  Nearly all of the Fresh water is in the form of Ice or underground.\n\nThis site appears to have a lot of data as well as activities for learning.\n\nhttp://members.aol.com/bowermanb/water.html
1168576
Number and biomass of algae is higher than trees so it is contributing in large amount. However, trees are contributing 25-29%. You have to consult\nDavid Lawlor. 2003. Photosynthesis\n\nM. Pessarakli (Editor) 2005. Handbook of Photosynthesis. Taylor and Francis, CRC Press USA
494215
If by "tillable" you mean "arable": i.e., land that can be used for growing crops, then about 12 million square miles (31,000,000 km²). That's about 21% of the planet's land area.
444694
Read Michael Crichton's State of Fear. From my various reading I have learned that the earth was warmer in 1300 A.D. long before cars and it was one of the most prosperous times in history. This was before the Black Plague, of course. More land was arable and human and animal populations were flourishing. It is really impossible to tell as the Earth is in the middle of a natural warming period right now. The tree huggers will never tell you about the glaciers in Iceland that are getting bigger and the parts of Antarctica where the ice sheet is getting thicker. I am a liberal, I am for nurturing the environment. I believe common sense dictates that vehicle emissions are bad for the earth in making our air more noxious, but to answer your specific question, nobody knows because there are too many factors.
556217
It's the most important part of our earth. Just like our body.. 70% portion of water is in our body.
434743
It's 78% of the earth's atmosphere.