Re: Will the greenhouse effect be noticble in the next 20 years?

What effects will the greenhouse effect have on the earth in the next 20 years. I have heard that it will turn wooded areas into grasslands. Is it probable that the oceans will rise, will a great quantity of the ice in arctic regions melt causeing the oceans to rise? How will this effect the ocean's species and what about Flordia? Will it be flooded?

The majority of atmospheric scientists seem to think that the effects will eventually be profound, turning (for example) wooded areas into grasslands. The reason for this is a redistribution of rainfall; a corollary is that some grasslands or deserts may become much wetter, converting them into woodlands.

I don't think there's a good consensus on how long it would take to melt the polar icecaps -- though 20 years is well outside the range of possible values; 100-200 years is more like it. The melting of the majority of the Arctic icecap would not affect sea levels, since most of it floats on water. On the other hand, total melting of the Antarctic and Greenland ice caps would affect sea levels, since most of these ice caps sit on land.

Here's an experiment: take an ice cube and put it in a measuring cup. Let it melt. What is the volume of the water in the cup? This is analogous to melting the Antarctic or Greenland ice cap.

Now take an ice cube and put it in another measuring cup. Fill the cup with water to exactly half-full and let the ice melt. What is the volume of the water in the cup? This is analogous to melting the Arctic Ocean ice cap.

Water levels would not effect oceanic life very much in themselves, and even the addition of such large quantities of fresh water would not have much effect. However, the global temperature rise associated with melting ice caps probably would have some effect, just as it would on land life.

The general consensus is that rising carbon dioxide levels are resulting in slightly higher average global temperatures, which are currently seen mostly in somewhat greater energy available in the atmosphere to form storms and other weather systems. Much of the doomsday extrapolation is not based on current CO₂ levels, but is rather of the "if this trend continues" variety. Thomas Robert Malthus used that sort of reasoning to predict, around 1800, that the human race would be mostly dead of starvation by about 1850...

Web sites which give more information on global warming:

• The EPA Global Warming Site.
• The Union of Concerned Scientists also maintains a site on Global Warming.
• A contrarian view is presented by Citizens for a Sound Economy.
• The so-called Junk Science Home Page is also skeptical .

Web sites on T.R. ("Bob") Malthus:

• A site maintained by a several-times great-nephew of Bob Malthus.
• A page which gives the basic thesis of Malthus' essay on population.
• Part of Berkeley's Evolution site, which discusses Malthus' influence on Charles Darwin.
• A general site giving emphasis to Malthus' economic works.