New York (CBS)  -- CLINTON, OBAMA DEBATE IN THE KEYSTONE STATE

In their debate in Philadelphia last night, sponsored by ABC News, Democratic presidential candidates Hillary Clinton and Barack Obama each said the other would make a good President.

She said he would.

"Yes, yes, yes.  Now, I think that I can do a better job," said Clinton.

And he said she would.

"Absolutely, and I've said so before.  But I too think that I'm the better candidate," said Obama.

Not that they don't disagree about things.

"Regardless of the differences there may be between us -- and there are differences -- they pale in comparison to the differences between us and Senator McCain," said Clinton.

One thing Senators Clinton and Obama agree on is how they'd react if Iran gets nuclear weapons and uses them on Israel.

"I would make it clear to the Iranians that an attack on Israel would incur massive retaliation from the United States," said Clinton.

"That would be an act of aggression that I would consider an attack that is unacceptable --- and the United States would take appropriate action," said Obama.

They disagree on raising the cap on Social Security payroll taxes.  Obama says he'd do that Clinton says she wouldn't. 

Both apologized for things they've said:  Clinton, for exaggerating the dangers she faced in Bosnia.

"You know, I'm embarrassed by it.  I've apologized for it.  I've said it was a mistake.  And it is, I hope, something you can look over," said Clinton.

And Obama for including religion along with guns and prejudice as things some small town Americans turn to when Washington overlooks them.

"I can see how people were offended.  It's not the first time that I've made a statement that was mangled up.  It's not going to be the last," said Obama.

The Pennsylvania Primary is in five days.

MAKE-OR-BREAK TIME FOR AMERICA'S RIVERS

A group called American Rivers says that global warming and ill-advised water projects are threatening our county's rivers.

"There are about a quarter of a million named rivers in this country -- about three-and-a-half million miles in total.  And I think it would be fair to say that probably nearly all of them are endangered by something or are stressed by something," said Rebecca Wodder, president of American Rivers.
 
The environmental group American Rivers has prepared a list of ten rivers at a crossroads, ten rivers for which a decision will be made in the next 12 months that will make or break the river.

"When you look at the list of 10 rivers this year on the most endangered rivers list, half of them -- five -- are threatened by global warming, because of droughts -- because of excessive proposals for water withdrawals that would kill the river and really not solve the problem," said Wodder.

The ten rivers are:  the Catawba-Wateree river in North and South Carolina, which provides drinking water for millions of people; the Rogue River in Oregon, one of our country's original wild and scenic rivers; the Poudre in Colorado; the mighty St Lawrence, on which tens of millions of people in two countries depend; the Minnesota River, a tributary of the Mississippi; the St. John's River, the longest river in Florida; the Gila River in New Mexico and Arizona; the Allagash Wilderness Waterway in Maine; the Pearl, in Louisiana and Mississippi; and the Niobrara in Nebraska. 

The list is a warning, says Wodder.

"And it's a preview, really, of coming attractions -- what's going to be happening in many communities across America that aren't prepared for droughts, that haven't taken important steps to use water wisely," said Wodder.

Read it and weep: Water will be the oil of the 21st Century, and our rivers are in deep trouble.

ASSESSING A NEW CLIMATE CHANGE STRATEGY

Did you think that we've been cutting down on those greenhouse gas emissions, at least a little bit?   Well, we haven’t.  In fact, they've been increasing. 

And now, President Bush has set a timetable for letting it continue to increase for the next 17 years, and then at that point.

"To stop the growth of U.S. greenhouse gas emissions by 2025," said Bush.

Not good enough, says Peter Frumhoff, the director of science and policy at the Union of Concerned Scientists.

"He's calling for us to stabilize our growth in emissions by 2025, when in fact what the science tells us is that we need to dramatically reduce our emissions of carbon dioxide and other heat-trapping gases in order to avoid truly dangerous climate change," said Frumhoff.

President Bush believes somebody will come up with something to deal with the greenhouse gas problem.

"The strategy I've laid out shows faith in the ingenuity and enterprise of the American people, and that's a resource that's never going to run out," said Bush.

The President thinks we've been going about dealing with a serious problem the wrong way.

"The right way is to set realistic goals for reducing emissions consistent with advances in technology, while increasing our energy security and ensuring our economy can continue to prosper and grow," said Bush.

Here's my plan, he says.

"We fully implement our new strong laws, adhere to the principles I've outlined and adopt appropriate incentives -- we will put America on an ambitious new track for greenhouse gas reductions.  Growth in emissions will slow over the next decade, stop by 2025, and begin to reverse thereafter -- so long as technology continues to advance," said Bush.

Peter Frumhoff says he hears what Mr. Bush is saying.

"And I think we are clearly in a position where no matter who the next President is, he or she is clearly going to take this issue more seriously -- and it's not a moment too soon," said Frumhoff.

THE FATHER OF "CHAOS THEORY"

Edward Lorenz -- who died yesterday at the age of 90 at his home in Cambridge, Massachusetts -- was a meteorologist. That's why he never won the Nobel Prize:  there is no Nobel Prize in meteorology.

But Lorenz won many other great scientific prizes, because his work affected so many other fields.  He was the father of what is now called "chaos theory" -- which is said to have brought about one of the most dramatic changes in mankind's view of nature since Isaac Newton. 

Meteorology is not an exact science, which we all know from the weather forecasts that are often wildly off the mark.  But it would be an exact science, if they know all the little factors that go into what actually does happen.  Small effects led to big changes. 

One day, when Edward Lorenz was a professor at MIT, he inadvertently ran what seemed like the same calculations through a creaky calculator, and came up with vastly different answers. 

He noticed that there was one infinitesimal decimal point change of 0.0001 -- well within what used to be called "wiggle room".  Such an insignificant thing, and yet it led to significant error.

He turned that "wiggle room" into hard numbers, and a scientific theory which he incorporated as the "butterfly effect."  He explained how something as miniscule as a butterfly flapping its wings in Brazil changes the constantly moving atmosphere in ways that could later trigger tornadoes in Texas. 

In his book "The Nature and Theory of the General Circulation of the Atmosphere," Lorenz laid out the general principles of small changes bringing big effects on which even today meteorologists base their forecasts, and other scientists base theirs.