How do the observed and reconstructed streamflow trends match up over the 1910-2005 period? What does the value of the explained variance in the calibration period (1910-2005) tell you about the strength of the relationship between the tree rings and streamflow in KAF? Hint: the closer an R2 value is to -1 or 1, the stronger the relationship. A value of 0 indicates no relationship at all. 

In this lab, we’ll focus on tree rings and their uses in reconstructing the streamflow of rivers to model past activity. Specifically, we can collect tree rings from a region and evaluate how current streamflow compares to streamflow of the past. The ability to place current hydrology of a region within the context of long-term hydrologic activity is exceptionally powerful in discussions of things like water resources, policies, security, and water rights.

 

Streamflow Part I — The TreeFlow Platform

Much research has been done by scientists all over the world using tree rings to reconstruct hydroclimate and streamflow. Dr. Connie Woodhouse at the University of Arizona, Tucson is a dendrochronologist who specializes in streamflow reconstructions, and has built the TreeFlow data platform. The work represented on this website showcases the international collaboration and dedication to this subfield of Geography.

Please go to the following website to begin the lab www.treeflow.info, and follow the steps outlined below.

 

· Explore the home page of the TreeFlow website in general – scroll through the pages and links, see what’s available up front at a first glance

· Click on the “Background” tab on the left-hand side of the page. Read through the Top 10 things you need to know (you may need to scroll a little bit down the page to find these). The powerpoint slides available provide further details and I strongly encourage reviewing them for deeper learning and engagement.

· Click on the “Basin Data Access” tab on the left-hand side of the page. Select the Pacific Northwest area on the basin map, which will bring you to all of the reconstructions available on this platform for this region.

· Read through the text provided and scroll down the page until you see the available reconstructions to look through…. Note: more streamflow reconstructions are created every year, so this is not a complete list! 

· Stay on this page to begin Part II!

Streamflow Part II – Snake River at Jackson Lake Dam

Submit a document that includes the following items upon submission – be sure to follow the steps and prompts below as you create plots and answer questions:

 

1. Click on the link for the Snake River at Jackson Lake Dam Streamflow Reconstruction Page and build two quick reference tables (an Excel spreadsheet works great here) with the following information:

a. One with the descriptive stats for both the observed and reconstructed flow periods (provided in the metadata)

b. One with the statistics for calibration and validation

2. Download the “snakemoran.xls” data file from the TreeFlow.info website and make two scatterplots:

a. One plot showing both the observed and reconstructed streamflow data for the entire time period (1591-2005)

b. One plot showing both the observed and reconstructed streamflow data for only the time period of observed data (1910-2005)

c. Be sure to title and appropriately label the axes of each plot and provide a legend. You may use whatever graphing software is most comfortable for you, but I strongly encourage Excel.

 

3. How do the observed and reconstructed streamflow trends match up over the 1910-2005 period? What does the value of the explained variance in the calibration period (1910-2005) tell you about the strength of the relationship between the tree rings and streamflow in KAF? Hint: the closer an R2 value is to -1 or 1, the stronger the relationship. A value of 0 indicates no relationship at all. 

4. What are some things that make reconstructing streamflow in the Upper Columbia River basin difficult?

5.How does current streamflow activity compare within the context of the entire available record?

Streamflow Part III — Applications

Please read Lost Cities and Climate Change by Kate Marvel. attached

 

6. How has climate change impacted civilizations in the past? Use and cite the article as needed for your answer here.

7.Based on what you learned from exploring

www.intersectionalenvironmentalist.com this week, how communities of color and those of lower socioeconomic status experience climate change. What are some reason(s) these communities are disproportionately harmed as a result of climate change?

follow the instructions+ due after 20 hours

Hot Planet

Some people say “the climate has changed before,” as though that should be reassuring. It’s not

Lost Cities and Climate Change

By Kate Marvel on July 29, 2019

Remnants of the ancient city of Cahokia, in what’s now southern Illinois. Credit: Steve Moses Flickr (CC BY 2.0)

Not far from my grandmother’s house is a ghost city. At Angel Mounds on the OhioYou have 1 free article left. See My Options

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river about eight miles southeast of Evansville, there are a few visible earthworks and a reconstructed wattle-and-daub barrier. There is almost nothing left of the people who build these mounds; in a final insulting erasure, the site is now named after the white settler family who most recently farmed the land.

There are traces of other dead villages along the Ohio and Mississippi rivers, mounds scattered from present-day Indiana to Arkansas and Alabama. In southern Illinois, a few miles from the Missouri border, hidden among empty corn and soy fields, is the center of that dead civilization’s gravity: the lost city of Cahokia.

Cahokia was larger than London, centrally planned, the Manhattan of its day. Most people there would have come from somewhere else. There were defensive foundations, playing fields, and a magnificent temple. There would have been sacred ceremonies and salacious gossip. It must have been a very exciting place to live.

And then, relatively abruptly, it ceased to exist. We know of the city only because of the physical traces left behind. Few stories of Cahokia have survived; it disappeared from oral tradition, as if whatever happened to it is best forgotten. The archaeological record shows traces of the desperation and bloodshed that almost always accompany great upheavals: skeletons with bound hands, pits full of strangled young women.

The North American Drought Atlas, a historical record of climate conditions pieced together from the rings of old trees, provides a hint of what might have happened. The tenth century CE, when the Cahokia civilization would have developed, marked a distinct shift in the regional climate from persistent drought to rainier conditions more suitable for agriculture, centralization, and civilization.

But the good times were not to last. In the middle of the fourteenth century, theYou have 1 free article left. See My Options

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climate swung back toward drought. This shift was likely associated with shifting temperature patterns in the ocean that affected the jet stream, pulling cool air down from the Arctic and displacing rainfall patterns. These changes are attributable to some combination of natural internal climate variability and externally forced changes from solar activity and increased volcanic eruptions. Their effects were profound.

In Europe around the same time, a confluence of natural factors perhaps related and perhaps separate from the forces drying out the Mississippi Valley caused it to rain heavily in the summer of 1314. The rains continued into the winter, and then into the next year, and then the next. Crops rotted in the fields, and the entire continent went hungry. Contemporaneous historical records complain of rain and famine, villages forced to eat dogs and cats, the dead, and even each other.

The Old World Drought Atlas, a collection of European and Mediterranean trees, shows a period of persistent wetness around the beginning of the 1300s that corroborates these historical accounts. Many of us unwittingly remember the famines in the stories we tell our children. The fairy tale of Hansel and Gretel —hungry children abandoned in a forest haunted by a cannibal witch—almost certainly dates from this time.

Many historical events have happened against a backdrop of natural climate change. Drought in the steppes east of Hungary pushed marauding Huns west and toppled the Roman empire. Volcanic activity suppressed crop yields in pre- revolutionary France, leading hungry, desperate peasants to take drastic action. But climate is almost never the only factor in human history. The Roman empire was overextended and tenuous, torn apart as much by infighting and poor governance as outside enemies. The French underclass starved under the policies imposed by the overclass.

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We humans are not passively dragged along by temperatures and rainfall patterns. Climate change did not cause the fall of Cahokia any more than it forced northern Europeans to eat their pets and abandon their children. But the adversity brought by climate change caused societies to break apart, magnified pre-existing divisions, and made desperate people easy prey for dangerous people.

“The climate has changed before,” say people who want to minimize the scale of the current challenge. I have never understood how anyone could find this comforting. The natural climate changes that have shaped human history have almost always been smaller and more regionally contained than the large-scale human-caused change we are currently experiencing. And even these changes have provoked suffering, scapegoating, and the collapse of civilizations.

I am often asked what frightens me most about climate change, whether I lie awake at night thinking about ocean hypoxia or arctic permafrost or other feedback processes that could turn a bad thing into a catastrophe. I am scared of the physical changes that await us on a warming planet, but the most important feedback process is the least well understood. The scariest thing about climate change is what it will make us do to each other.

The views expressed are those of the author(s) and are not necessarily those of Scientific American.

A B O U T T H E A U T H O R ( S )

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Scientific American is part of Springer Nature, which owns or has commercial relations with thousands of scientific publications (many of them can be found at www.springernature.com/us). Scientific

American maintains a strict policy of editorial independence in reporting developments in science to our readers.

© 2020 SCIENTIFIC AMERICAN, A DIVISION OF NATURE AMERICA, INC.

ALL RIGHTS RESERVED.

Kate Marvel

Kate Marvel is a climate scientist at Columbia University and the NASA Goddard Institute for Space

Studies. She received a PhD in theoretical physics from Cambridge University and has worked at

Stanford University, the Carnegie Institution, and Lawrence Livermore National Laboratory. Her writing

has appeared in Scientific American, On Being, and Nautilus Magazine, and she’s given talks in places

as diverse as comedy clubs, prisons, and the TED main stage.

Credit: Nick Higgins

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