CLIMATE AND CLIMATE CHANGE IN THE
SOUTHWEST—LECTURE
Margaret Mayer
Is Climate Change occurring in the Southwest? Yes, the Southwest has been in drought for the past 10
years, and according to forecasts from numerous sources the temperatures in the Southwest will
continue to be hotter than normal and the Southwest will continue to be in drought for a decade or
decades. To better understand climate change we will look more closely at the type of climate and land in
the Southwest today as well as in the past so one can see trends, as well as look at adaptations of Native
Americans to this area and climate.
When you think of the Southwest what comes to mind? Desert, dry and hot. (photo) Are all deserts hot
and dry? Actually not, since although much of the Southwest is desert, the northern areas are cooler
not just due to latitude but because they are part of the high Colorado Plateau in northern Arizona, New
Mexico, and Southern Utah and Colorado: land of the Navajo, Hopi, and Ute Reservations. This is quite a
contrast to the hot Sonoran Desert of southern New Mexico and Arizona, home to such tribes as the
Tohono O’odham and Pima. Compare the two photos: What makes you know this is the Sonoran Desert?
(Saguaro cactus in an indicator plant (explain: Indicator plants are the dominant organism found in a
specific climate or community type), whereas on the Colorado Plateau it is too cold for saguaro cacti.
Think of the temperatures in Phoenix---in the last years reaching 120 resulting in fatalities, particularly of
the old and poor without air-conditioning.
These two types of deserts are quite different but now we are seeing movement of organisms which
typify the more southern deserts moving north and temperatures and drought increasing in the northern
plateau land as well as the southern areas. (Students go to Audubon website to find out what species of
birds are moving north) Diseases such as West Nile virus and malaria are moving north just as diseases of
plants and forests.
Although temperatures may vary from high and low deserts all are typified by low precipitation. How
many inches of rainfall typify a desert? 15” or below. Much of the Southwest except some mountains is
that dry. What is the crucial limiting factor (factor which limits growth and life) to live in desert
environments? Water. Not only is there little precipitation, but usually and especially in drought years
evaporation exceeds precipitation resulting in even less water. When droughts continue as now this
stresses organisms, for example weakening the immunity of forests to fight disease as we see throughout
the western forests today----with the pine killing pinion trees, of vital importance to the Navajo as food,
wood and building materials, Spruce bud worm killing off entire forests in Colorado just as whole hillsides
of aspens are dying.
Another question is where does the water come from in the Southwest? Most people immediately think
of the Colorado River (map) (Students are to do map exercise locating and naming the major rivers and
drawing the extent of their drainage basins, locating the source of the rivers, identifying the mountains,
and labeling the dams. Ask them to identify where the water comes from. Ask them to identify a point on
the map where they would like to live or visit, and then identify the smaller drainage basin and then its
largest drainage basin its part of (for example Chinle Wash which drains into San Juan , part of the
Colorado River) The Colorado River is the life-blood of much of the Southwest including the Navajo
Reservation and the drainage basin (area including the river, and all land and mountain ridges from which
the tributaries arise) is immense. The dominant river and drainage basin of New Mexico is the Rio Grande.
Other rivers include the Salt River near Phoenix, and the Gila in the South. What is the source of Colorado
and most other rivers of the Southwest? the mountains, and of particular importance, the winter
snowpack. Across the region snowpack has decreased in the last decade, such as in the Chuska Mountains
of the Navajo Reservation (graph) or the deep long snows in the Flagstaff area are a thing of the past.
Although the San Juan Mountains, southern Rockies received substantial snow this year, the snowpack is
melting much earlier and faster. Guess what caused the early melting. The snow covered peaks of the San
Juans are brown from dust (photo) carried by the severe dust storms this spring from the Navajo
Reservation to the northern mountains. How did this cause increased melting? White snow reflects the
sunlight thereby retaining the snowpack vital for continual flow of streams and rivers throughout the
summer and fall and to continue the flow of the Colorado and other rivers in the Southwest. Increased
drought leads to more erosion and more dust. Global warming is associated with increased severe
weather such as dust storms.
Four mountains are of special significance on Navajo land-the 4 Sacred Peaks bound the reservation in the
4 directions: Hesperus to the north, Blanca to the east, Mt Taylor to the south, and the San Francisco
Peaks to the west. These peaks give water, mostly through their snow pack and not only tribes say: Water
is Life. San Francisco Peak is a lovely volcanic cone which one can see on the horizon from many parts of
the reservation. There has been an intense debate involving Native Americans on one side and a ski area
on the other.
Some questions:

Is the Southwest currently in a drought ?

Is climate change occurring in the Southwest? What scientific evidence?

Is the present and future like the past patterns? Or different?
HISTORICAL PERSPECTIVE NATIVE AMERICANS LECTURE
Perspective: Climate thru time and historically: this area has been desert and dry.
History of Native Americans living and adapting to desert Southwest:

Look to past Anasazi—(Ancient Ones)

Earliest Native Americans (date)(photo Anasazi ruins)- built pueblos -such as Canyon de
Chelly/Chaco/ Wupatki/Hovenweep---and lived for hundreds of years (date) in desert
environments of Southwest, utilizing conservation hydrologic features—(photo small dams/ or
series dams in a drainage and suddenly vanished (1300)
Where did they go? Why?

Drought? Wars? overexploitation of land as population grew?

What scientific evidence is there to support drought and lack of water
o
We look at pollen
o
We look at middens—plant and animal species change
o
Chaco (photo) utilize large logs (no trees grow now in area)
Hopis believe they are ancestors to the Anasazi and that they migrated to other areas. Native Americans
in the Southwest always have adapted to desert and drought. Knowledge of how to live in desert
environments from hundreds of years experience involving “cycles” of recurring drought followed by
years not so drought prone. Climate change is part of the Southwest as well as globally.
Adaptation of tribes to living in Southwest desert:

Water collection---dams, ditches

Knowledge of seasons and times of rainfall

Knowledge edible native flora/animal migratios and crops/animal

Navajo—lived hundreds of years in Canyon de Chelley (photo)

Thono O’odham ---- branching -water collection- (photo)

Hopi –“waffle” (photo)
Questions so far????? (Brainstorm with class)

Historically were there drought cycles?? Of how long duration??

Have all tribes retained their knowledge of specific adaptations to climate change? (photo of
some current dams, some unused dams/ unused fields on Navajo)

What can be done to access this information and make it available to the people?
GEOLOGY SOUTHWEST
Perhaps we need to first look more closely at climate through time, using a Geologic Perspective on
Climate Change in Southwest
Climate change has always been part of the Southwest but has the Southwest always been desert? We
need to look back further in geologic time before humans.
 (photo Petrified logs) What is this? How did it form? What does it tell you about climate change?
(Have students brainstorm for answers)
This is a petrified log which can be found throughout major parts of tribal lands and Petrified Forest
National Park, AZ, Petrified logs as all fossils provide scientific evidence of past life and climate. These
logs are part of the Chinle Formation, layers of rocks which show that once tropical forests and swamps
existed here in what is now desert. The trees died, were buried, and silica rich mineral solutions
infiltrated the wood, petrifying them for posterity.
The cliffs and walls of Canyon de Chelly, Navajo National Monument, Zion National Park, and the
Coconino Formation in the Grand Canyon show swirls and diagonal markings. (Photo) What might these
indicate the environment and climate was when these layers were put down? Sand dunes, like the Sahara,
once stretched across much of the Southwest, indicating time periods even drier than today.
The hogback (photo) near Shiprock, NM contains marine fossils: clam and snail shells. Once (map photo)
an inland sea extended from Colorado south through New Mexico to Mexico border. Fossilized corals and
sponges on top of El Capitan (photo), Guadalupe National Park give more scientific evidence of this.
Most of the fantastic layers of the Grand Canyon are Paleozoic Era one of the oldest geologic eras, 550250million years ago when much of the southwest was ocean, advancing over land, or retreating,
changing through time, like climate change. Marine fossils in the layers are the scientific evidence.
(photo)
So what does this tell us?? (Let students answer)-----That throughout Earth’s history climate change has
occurred. (Is someone else covering this topic?)
Why did climate change occur? The Earth’s crust is made up of tectonic plates, which move apart or
together. When you look at the map of North American and South American, Europe and Africa do you
notice anything about the shape of the continents? (Wait for student responses) Do you see how they are
like a jig saw puzzle you can put together? Once the continents were together in one supercontinent
called Pangaea and then the tectonic plates began to separate (called continental drift) in this case
creating the Atlantic Ocean and the continents as we know it, and that is still happening with the Atlantic
Ocean getting bigger.
What has this to do with climate? How is the climate different along oceans and bodies of water and the
interior of a continent? (Wait for response) Coastal regions have more moderate climate, whereas
interiors have more extremes: hotter summer, colder winters. Why is that? Water takes longer to absorb
and lose heat, than the earth. (Lab on this?) So relate this to the Southwest: Today much of the
Southwest in far from water with more extreme weather; whereas back in time when oceans extended
over this area, the climate would have been more moderate, so that swamps and tropical forests could
exist here.
At the top of the Himalayas one finds fossils of marine creatures telling us this under the ocean, which
leads us to another way continental drift and plate tectonics affects climate. Is it usually warmer or colder
at the base of the mountain? Usually warmer at the base and colder at the top, so if you have more
mountains it will be cooler than lowlands. So now we understand more about the Southwest’s climatic
history. Great oscillations of climate have occurred in the past including in the Southwest, so climate
change occurring now is just a natural phenomenon. Correct?? Not quite, The changes of that took place
in the geologic past occurred over long periods of times: millions of years, However , climate change
occurring today is happening very fast: within a few hundred years! (See Chart—I’m sure someone is
covering this already) so what will be the difference of impact?? (Wait for student response) We have
talked about how Native Americans have adapted to climate change in the past in the Southwest.
However, can Native Americans adapt when the RATE of change is greatly accelerated and that here in the
Southwest it is desert already. and how much knowledge is retained by the tribes of the Southwest and
what can be done to access and make that knowledge more available to all tribal members and all tribes?
HOW NAVAJOS
ARE AFFECTING WATER CYCLE TO
DECREASE WATER ON THE LAND AND INCREASE
DROUGHT AND DESERTS:
You already know about how the water cycle works. We know there is 15” of rain or less in general in the
Southwest, and you know what happens to that water when it hits the ground (Diagram water cycle). But
what happens to much of that precipitation in the desert—arid Southwest---Much evaporates. Big dams
have been built in the Southwest to conserve water: Lake Powell, Lake Havasu, Lake Meade. How much of
that water evaporates? (photo chart and that is increasing )
Is evaporation directly related to the sunny days and the heat from the sun, but are there other factors
occurring in the Southwest and tribal lands? (Wait for response— students could do field study relating to
this) What about cities such as Phoenix---one of the largest growing cities in the West? Is it hotter in a
city or in the countryside outside? Hotter in the city. Why? Much is under concrete----absorbing the heat
from the sun and radiating that back out, increasing temperature and evaporation, and increasing run-off
of the water. Many Native Americans have left their reservations for the cities, but what are factors on
the reservations which increase evaporation and run-off. How much of the land is vegetation? How much
bare ground? Here on the Navajo reservation (photo) a considerable proportion is bare ground. How does
that effect water retention? Vegetation: trees, forest, shrubs, grasses act like a sponge absorbing the
water---and holding the water, and then through transpiration (movement of water up through the roots
and evaporating into the atmosphere from the pores or stoma of the leaves) increasing the water vapor in
the atmosphere. Which does what? Water vapor rises, cools, condenses so to increase precipitation.
Water cycles through vegetation into the atmosphere then back to the plants as precipitation. If the land
is bare, the water cycle is cut---the water just flows off. And water to most native peoples, actually all
people, is LIFE. But you say the Southwest has been desert for hundreds and thousands of years, and
there’s always been bare ground in the desert Southwest. Actually not, there is record of many areas of
the Navajo Reservation including Shiprock area of being on horseback with grasses 6’ tall. You might say
well that was not a time of drought. However today if you compare Hopi land with Navajo land nearby
(photos) what do you see? Tall grasses on Hopi, little on Navajo land----or just drive the roads on the
Navajo Rez –along the roads outside of the fence tall vegetation, inside the fence little. What does that
tell you?
Hopis are farmers raising corn, but Navajos are sheep herders, as well as cows and horses. Overgrazing----having too many animals on the land which eat the vegetation creating and expanding the bare ground.--increasing desert. Desertification (increase of deserts) is not just caused by increase temperatures, but is
anthropogenic (human caused).
The Sahara in Africa is increasing as the people in the Sudan to the South overgraze their lands, creating
deserts. So we are helping create more deserts, we are cutting the water cycle, we are increasing the
temperature of the land. Creating bare ground increases erosion, which increases loss of water and
vegetation. When you drive the reservations how else do humans increase bare ground? How many roads
are there to granny’s Hogan?—12!---each one increasing run-off of water. How does the sheepherder herd
sheep? Often not on foot or a horse any more, but with vehicles—ORV or truck destroying fragile crust.
Here in the desert Southwest if the bare dunes or soil is left without being damaged by hooves, footprints,
vehicles, a blackish crust develops. (photo)
This is called cryptozoic or biozooic soil, where bacteria, blue-green algae, fungi, and lichen begin to grow.
It can take a hundred years to develop. What good is it? These organisms form a crust—when you touch
it it is hard, and they hold the particles of soil or sand together which stops erosion, and these organisms
absorb and hold water so that when seeds of grasses or a piñon or juniper tree land, the seeds can take
hold and germinate, leading to succession, the change from bare ground to different plant communities.
Here on the Navajo reservation it is difficult to find cryptozoic soil, because the land is trampled by
animals. So we as humans could increase the conservation of water by doing what? (wait for response)
1.
reducing number and types of grazing animals (grazing of 1 horse equals 6 sheep) on the land
2.
reducing number of dirt roads
3.
herding animals by foot or horse, reduce orvs and other vehicles on the land
4.
reduce cutting of trees, begin watershed protection with education on these issues
5.
educate people on production (amount of vegetation) and stocking rates (number of animals
which production of an area of land can support) (Could do a lab on this)
So now we know some measures we can do now to conserve water,and to maintain the water cycle, part
of which is about surface water: rivers,lakes, and streams. Increasing erosion of streams ( by grazing,
vehicle use, lack of vegetation) will increase flow and run-ff of the water, and the opposite is true and
beneficial. So let’s look at surface water: rivers, lakes, and streams in the Southwest. When you think of
the Southwest which river does everyone think of? Think what could occur if all the water conservation
measures discussed above would occur throughout the Southwest and tribal lands? Each tribe has
conservation offices, but are the people who live on the reservation aware of these and do they practice
them?
If you look at the Southwest (map) what type of lands surround the tribal lands? Do river drainage basins
stop at tribal boundaries? No drainage basins are shared with tribal lands in the Southwest to a large
degree by National Forests, BLM land, and National Parks. National Forests and Parks have watershed
protection policies in place and tribes need to coordinate with them.
Other climate factor dominating the Southwest: monsoons
Have students read article or research monsoons. Explain what they are, how they relate to El Nino, what
that is, the cyclic nature, the causes of that. Is monsoon season affected by climate change?
Info:
Monsoons are heavy rains. The term comes from India where often torrential rains occur part of the year,
alternating with a dry season. Monsoon season in the Southwest generally begins July through
September and is a vital source of rain for the Southwest.
Like many tribes, Navajo talk about 2 kinds of precipitation: male rain and female. What do you think the
difference is? Male rain is stronger and can be violent often in the form of thunderstorms which can
result in major run-off and erosion of arroyos, or death of people unable to escape the quickly rising
waters of a stream. Female rain is gentle and is more easily absorbed and held by the ground. During
monsoon season much of the rain comes as male rain, thunderstorms—which, although torrential rain
can be result , much leads to run-off. However, this summer precipitation still gives water to the land and
plants, and leads to a second flowering season (the first being spring, with much of the moisture in the
mountains of the Southwest coming from melting snowpack).
We also need to add in terms of climate of the Colorado Plateau and mountains, that since they are high
in elevation, and north of the southern parts of the Southwest, the precipitation in winter often fall in the
form of snow, which is a major source of water for the Colorado River drainage basin, as is the Rio
Grande.
EVIDENCE OF CLIMATE CHANGE IN SOUTHWEST
All graphs, maps show the Southwest as being in a drought for the past 10 years, with increasing
temperatures, excepting this past year. (Need to look at long-term perspective—trend, not individual
year.)
Available water for humans and grazing animals reduced
Vegetation reduced due to lack of water and overgrazing-reduce vegetation (works in cycle), increase
erosion, increase starvation and death of stock animals
Increase invasive species adapted to drought and which can germinate and spread more easily on bare
ground:

Cheat grass,

Spotted knapweed

Russian thistle (tumbleweed)

Bull thistle and other introduced species
Collared dove moving increasing north
Killer bees moving north
Increase diseases such as

East Nile virus

Malaria

Tree diseases----pine beetle infestations in Pinion pine

Diseases and death of aspen groves, spruce
Increase forest fires, impact wildlife and homes, loss vegetation
Increase violent storms----spring dust storms this year-----major erosion cover snow of San Juan Mts
brown (reduce albedo –white—to reflect sun, instead absorb sun to cause early melting of snow fields,
which is the source of the Colorado River and much of the water in the Southwest)
(Reading—articles on increase erosion/dunes Navajo—M. Hiza; Dunehandout.pdf)
Impacts
 endangered flora such as Mesa Verde cactus near Shiprock, NM (photos)
 List other species and show photos
 Diversity of species decrease
 Loss medicinal and cultural species
 Increase movement of native species---Native birds moving north ( Students see Audubon link--could have this on animal distribution)
 Heat related deaths on tribal lands and cities
Cause climate change –relate to Southwest
--Other topic cover cause of change----CO2 due to burning fossil fuels---tribal lands adding to that:
 Coal burning power plants rim tribal lands in Southwest 6 around Navajo(list)
 Desert Rock—new power plant proposed near Shiprock on Navajo, supported by
 President Shirley
$/short-term jobs vs environmental and human health Energy –which
energy source?? Nuclear---tribal lands rich in resources (coal/uranium)
 President Shirley bans mining uranium due to health effects on Navajo in past
Alternative energy for future
 Solar
 Wind
 Conservation---insulation houses, strawbale/ tire houses