OK. Let me explain.
You probably know that we can determine a tree's age by counting the rings on a cross section of its trunk.
Each ring represents one year of the tree's life.
So if you know the year the tree was cut, you can count inwards and date each ring all the way back to the center.
You can also tell how much moisture the tree got during each of those years by looking at the width of the rings.
A wide ring means plenty of water while a narrow one indicates less.
Fortunately for us, certain areas of the Colorado River basin are home to some very old trees, some 800 years old and older.
Researchers can drill core samples, uh, basically get a cross section of a tree without having to kill it, look at the rings and get a picture of what the climate was like in the basin for each of the tree's years.
Well, the results tell us something we wouldn't have known without this data, that over the past 500 years or so, the Colorado River basin has experienced severe droughts, some worse than any we've ever recorded.
They also showed that the early to mid-1900s, when most of the data that led to the water-sharing agreement was collected...well, this was the wettest period in the past 400 years.
Well, obviously, had water management officials known then what we know now, the 1922 agreement would have been handled differently.
But today we can use the past to help prepare us for the future.
With the demand for water in the basin stays increasing and with the real likelihood of lower flows in the river, if history is our teacher, we can develop innovative methods of water conservation and reevaluate how water is distributed.
What is the lecture mainly about?
What does the student find surprising about the 1922 water-sharing agreement?
According to the professor, what was the problem with the data recorded before the 1970s?
What assumption did researchers use to draw conclusions about the Colorado River basin?
What does the professor imply when he describes the early to mid-1900s as the wettest period for the Colorado River in 400 years?
What is the professor's attitude toward future water-management plans in the Colorado River basin?