Next up today, the issue of climate change-globaltemperatures indicate that Earth has been gettingwarmer in recent decades.

But there's been debate about what's causing theincrease.

A new report says many scientists are more certain than ever that the culprit is human activity.

Tom Foreman examines the potential effects.

You know about climate change, the idea that basically greenhouses gases are trapping heatfrom outside, and you're correct,

they are now well over 90 percent saying that human activity is responsible for thepreponderance of this,

important to know, they're sayingthere are other factors,

but the preponderance of it is coming as a result of humans doing this.

So, what is making-what is the result of all this?

Rising oceans.

Why? Because we have warmer oceans,

and those warmer oceans are causing melting ice caps, and beyond that, melting of glaciers andother large ice areas in the world, for example, Greenland.

And I want you to watch this amazing piece of animation from NASA here.

Tracking over the past few years what's been happening to ice up in Greenland.

You see all these light blue areas around the edge there-that's where the ice has been steadilymelting and retreating, in this entire country of Greenland.

And as you go on through the years, this is about to 2005 here,

as it moves forwards, you start seeing even the middle of the country here as it startswarming up, and they are losing even more and more ice.

By the time you get through this entire animation,

what you see is that NASA has captured how basically this entire area has seen significant lossin ice,

all of which goes out into the oceans and that's the real key here to concern about what'sthat's going to add up to in the long run.

We move on beyond this, if you look at Miami down here.

This is where Miami is right now.

Everglades National Park,it's a little bit hard to see,

but I want you to watch-as this progresses,

what they are predicting is that over the next 80 or 90 years,

if nothing changes, what you would see is a real encroachment.

Areas like this down here, where you have the Florida Keys, they would basically go completelyunder water and a lot of areas would also be affected by much, much higher water levels.

And even if you go to major cities, like New York City, for example - look at this.

This is the island of Manhattan right here.

Right now this is the edge of it, and you can see, that's where the new edge would be.

All of this out in here would be lost.

What would that include-well, the simple truth is if you had it lost all the way out there,

you would see things like Wall Street essentially starting to go under water,

you would see the Statue of Liberty, the island that supports it out here starting to go underwater.

Does that mean it will happen?

No, we have a lot of time, in which people could build levees and that sort of thing to keep itback,

but it does mean it would become a genuine problem if this goes on unabated, and that'swhat this whole debate is about,

and now there's an even greater agreement among all these climate scientists from around theworld that,

in fact, humans are making some of this happen, and only humans can stop it from happeningworse.