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Climate
change threatens northern Arizona
Global
warming may lead to droughts, floods or drifting sand dunes in the
region
By
Lisa Rayner
Tea Party Publisher
Global
warming is now a reality. Globally, the 1990s were the warmest
decade since instrumentally recorded weather keeping began. In April
the National Oceanic and Atmospheric Administration released
preliminary figures for 2002. So far, 2002 is tied with 1998 as the
hottest year in the historical record. March was the warmest of any
March in the historical record, 1.39 degrees Farenheit above the
long-term mean. March was also the second-biggest temperature
anomaly on record, after February 1998.
Recently,
even the Bush Administration reluctantly acknowledged the reality of
climate change when it released its Climate Action Report 2002,
which is discussed in more detail later in this article.
Evidence
of global warming in the Southwest is also clear. During the 20th
century, average temperatures in the region rose by 2–3 degrees.
Average temperatures are predicted to rise as much as 9 degrees or
more during the 21st century, a magnitude of change as
great as the end of the Ice Age 10,000 years ago.
As
the Earth heats up, global warming-induced climate change is
beginning to alter climate patterns worldwide. Northern Arizona,
like the rest of the Southwest, is known for its fluctuating weather
patterns and climatic extremes. A 1999 University of Arizona
Laboratory of Tree-Ring Research paper entitled, “The Climate of
the Southwest,” reports, “Climate variability is the norm within
this region as temperature and precipitation fluctuate at time
scales ranging from seasons to centuries. … Southwest
precipitation is especially variable, with regional floods or
droughts severe enough to affect both indigenous and modern
civilization on time scales from single growing seasons to multiple
years, even decades.”
Research
indicates that climate change will make those patterns even more
dramatic and uncertain. These changes will have significant impacts
on local and regional water supplies, forest fire potential,
wildlife and biodiversity, ranching, agriculture, human health and
energy production throughout this century and beyond.
A
climate of variability and extremes
Weather
across the Southwest is typically warm, sunny and dry. This is due
to the sub-tropical high-pressure ridge of air that sits over the
region most of the time.
The
annual weather cycle of northern Arizona fluctuates between two wet
and two dry seasons:
Spring
in northern Arizona is especially sunny and dry. Strong winds come
from our primary Southwestern wind direction.
Then
during mid-summer, on average in mid-July in northern Arizona, the
winds shift direction as a low-pressure trough pushes aside the
high-pressure ridge. This shift is known as the North American
Monsoon. These winds bring cool, moist air from the eastern Pacific
Ocean, the Gulf of California, and to a lesser extent in northern
Arizona, from the Gulf of Mexico.
Our
high summer surface temperatures cause atmospheric convection to
collect the moisture into cumulus clouds. The turbulence produced by
the interaction of the cool air mass and the warm ground surface
often turns the cumulus clouds into full-fledged thunderclouds. When
the atmosphere finally reaches the saturation point, rain falls.
Monsoon
rains come in “bursts” lasting for several days or weeks,
interspersed with high-pressure dry “breaks.” The duration and
intensity of the monsoon rains varies year-to-year and
decade-to-decade. These variations are linked to shifts in the
high-pressure ridge.
In
early autumn, the winds shift again, returning the subtropical ridge
over the Southwest. Occasionally, tropical cyclones in the Pacific
and Gulf of California stray northward and bring heavy rainfall to
northern Arizona at this time of year.
During
the winter, Pacific storm tracks usually enter North America over
the Pacific Northwest, leaving the Southwest dry. When these storms
reach very large diameters of about 2,000 miles across, their
southern tips brush across northern Arizona. Periodically, Pacific
storms enter the continent over California. These southerly storms
bring heavy winter precipitation to northern Arizona.
While
our precipitation is roughly split between summer and winter, more
precipitation usually falls during the summer monsoons than during
winter storms. However, our high summer temperatures and intense
high-altitude sunlight create high evaporation and transpiration
rates, preventing most of the summer moisture from nourishing
vegetation and recharging surface and groundwater. Thus, winter
precipitation is key to local surface and groundwater recharging.
The
Earth's oceans and atmosphere are intimately connected. Temperature
changes and shifts in water circulation and wind patterns are tied
together. One such temperature fluctuation, the El Niño/Southern
Oscillation, or ENSO, occurs in the surface waters of the central
and eastern equatorial Pacific Ocean. ENSO shifts the active center
of atmospheric convection over the Pacific back and forth between
the western and central equatorial Pacific. This shift in turn
alters winter storm patterns across the Southwest. The two extremes
of this fluctuation are known as El Niño and La Niña. ENSO has a
2–10-year cycle, with an average interval of 3–4 years between
extremes.
During
an El Niño extreme, the water warms several degrees above average.
The convection center shifts to the central Pacific. Winter storm
tracks shift southward, bringing cooler and wetter winters to the
Southwest.
During
a La Niña extreme, the ocean cools by several degrees. Atmospheric
convection shifts toward the western Pacific. The winter storm track
shifts northward, leaving the Southwest warm and dry.
Another
fluctuation pattern affecting Southwestern weather is the Pacific
Decadal Oscillation. The PDO is a fluctuation of surface
temperatures in the northern Pacific Ocean that occurs on the order
of decades. Periods of warming correlate with higher winter
precipitation across western North America. In addition, warm
periods correspond to stronger ENSO extremes, while cool periods are
linked to a dampening of the ENSO fluctuation.
Actual
day-to-day and seasonal weather results from the complex interplay
of these cyclical patterns and others (some we do not yet know
about) and their interactions with local topography.
While
modern climate records have only been kept for a little over 100
years in northern Arizona, tree-ring data and other paleorecords
extend climate information back more than 1,000 years. The
reconstructed climate record shows considerable and complex
variability. A number
of climate cycles have been identified, including 80-year and
20-year precipitation cycles.
Prolonged
drought periods in the Southwest have lasted as long as 200 years.
The most extreme drought of the previous millennium occurred in the
1500s. The most extreme drought in the 20th Century
occurred in the 1950s.
A
wetter 20-year period occurred during the 1970s and 80s, a period of
explosive population growth and sprawl in the Southwest. In the
1990s, the climate appears to have swung into a drier period. 2002
is turning out to be the most extreme drought year since climate
record keeping began in 1898.
Global
warming comes to northern Arizona
The
most comprehensive study of the effects of climate change in
northern Arizona is the U.S. Global Change Research Program’s
regional report, Preparing for Climate Change: The Potential
Consequences of Climate Variability and Change: Southwest. The study
combined extensive data from a number of individual climate change
studies of the Southwest, as well as several new studies conducted
specifically for the assessment. The report was published in
September 2000 and is on the Web at www.ispe.arizona.edu/research.
Physicians
for Social Responsibility (www.psr.org)
published a comprehensive report in September 2001, entitled, Death
By Degrees: The Health Threats of Climate Change in Arizona.
Preparing
for Climate Change says of the predicted 9-degree temperature rise
during this century, “The seasonal (temperature) extremes will …
likely exceed anything in the recent historical record. It is also
probable that daily extremes would set new high-temperature
records.”
Global
warming increases the severity of individual storms. This is because
the added heat does not merely raise the air temperature. Much of
the heat fuels increased wind speeds and storm sizes. Global warming
also increases the extremes of climate fluctuations, producing both
more extreme droughts and more intense storms and flooding.
It
is predicted that weather this century will involve extensive
drought periods interspersed with an increasing number of El Niño
winters. Climate of the Southwest notes that, “El Niño events
have outnumbered La Niña events by a ratio of nine to one over the
last 20 years, whereas they used to occur approximately equally
before.”
Because
El Niño winters are wetter, northern Arizona could well receive more
precipitation than it has in the recent past. On average, the
Southwest is predicted to experience a doubling of annual
precipitation in the next 100 years, mostly during the winter.
However, the actual changes in precipitation across the Southwest
over the previous century have been variable. Some localities show a
decrease, including northern and southern Arizona. Other areas show
a precipitation increase, including central Arizona. In addition, the
newer Hadley CM3 climate change model predicts drier conditions
throughout the Southwest.
The
implications for local and regional water supplies are thus
uncertain. Higher precipitation during El Niño winters and autumnal
tropical cyclones could lead to greater recharge of local surface
waters and aquifers. However, the warmer average surface and air
temperatures will cause higher rates of evaporation, which might
lead to less surface and groundwater recharge. In the past decade,
evaporation rates have quickly lowered regional lakes. In addition,
springs are drying up across the region.
Much
of the snowfall in northern Arizona does not melt into the ground,
but rather “sublimates” directly into the air. Higher winter
temperatures lead to faster melting and sublimation of snow, and
thus less groundwater recharge.
In
addition, floods recharge groundwater less efficiently than
lower-intensity storms do. Flood runoff flows across the ground
surface, eroding soil and flowing into major tributaries, rather
than soaking into the ground over a wide area. Drought years
exacerbate flooding potential by compacting the soil.
Furthermore,
global warming is predicted to decrease precipitation, especially
winter snows, in the Rocky Mountains. Over the past 50 years, the
Southwest has grown highly dependent on Colorado River water, which
originates in the Rocky Mountains, to irrigate farms and supply
water for homes and industry. A number of local governments,
including the City of Flagstaff, the City of St. George, Utah and
the Navajo and Hopi Tribes, are hoping to supply their growing
populations and economies with Lake Powell water. In addition,
Peabody Energy, owner of two coal mines on Black Mesa, is hoping to
stop drawing Navajo Aquifer water by switching to Lake Powell water.
Meanwhile, the elevation of Lake Powell is dropping steadily, in
part due to lower snowmelt waters from the Rocky Mountains and in
part due to higher evaporation rates at Lake Powell itself.
Throughout
this century, it will become increasingly necessary for communities
in the Southwest to store water from wet years for use during dry
years, as well as to implement better flood control plans to avoid
flood damage to buildings, streets and utility infrastructures.
Increased flooding will also expand arroyo cutting in rural areas,
leading to increased damage to farms, rangelands and wilderness
areas.
Heavy
precipitation is also a danger to mining operations. Preparing for
Climate Change says, “A typical mining operation must collect and
use or process all precipitation that falls within the limits of the
facility, or that otherwise comes into contact with unnaturally
exposed material. … Infrastructure at a facility is developed to
handle expected amounts of precipitation. … If magnitude and
frequency of storm events increase, systems in place may be
insufficient to prevent successful containment of excess water,
leading to pollution of streams and groundwater.”
“The
amount and the quality of water supplies in today’s highly
engineered storage and delivery systems are severely dependent on
precipitation falling at the right time, in the right place, for a
sufficient amount of time, and in sufficient volume,” says
Preparing for Climate Change. “Even groundwater stores not
recharged by rainfall are affected, as the utilization of water
depends in part on the effects of temperature and precipitation on
demand: if some of the demand can be met by rainfall, the amount
pumped from the aquifer may decrease. … Given the expected
population growth (in the Southwest), it is estimated that neither
precipitation nor conservation measures will have a significant
impact on drastic depletion of local aquifers.
“Adverse
effects of the 1950s drought, which was quite severe, were buffered
by irrigation from groundwater. However, groundwater tables are
lower now than before and are likely to continue dropping throughout
the 21st century, making it ever more expensive to pump
groundwater.”
Increased
drought and flooding will impact local ecosystems as well. During
wet years, vegetation will increase. Then when the next drought year
hits, there will be more vegetation to burn in forest fires.
“Based
on a 300-year record of climate and fire,” says Climate of the
Southwest, “a pattern of one or more wetter-than-normal El Niño
winters in the Southwest, followed by a drier-than-normal La Niña
winter, establishes preconditions for unusually large and intense
wildfires. Further, certain kinds of episodic ecological
disturbances, such as insect outbreaks, may be traceable to patterns
in climate variability.”
Researchers
are concerned that more numerous drought years combined with more
intense wildfires could lead to significant areas of Ponderosa pine
forests being replaced by grasslands — as much as 30 percent,
based on studies of past droughts.
Pinyon-juniper
woodlands are at risk, too. A study of the pinyon-juniper woodlands
at Sunset Crater by the NAU Pinyon Ecology Research Group found that
“Pinyons growing on many of these sites had high rates of
mortality following an extreme drought in 1996. (Due to climate
change), in some areas, a pinyon-juniper woodland may become a
juniper woodland — a major (ecological) change.”
Rangelands
are also expected to be negatively impacted by climate change.
Preparing for Climate Change says, “Semiarid ecosystems are
vulnerable to shifts of dominance and structure that are not easily
reversed, as shown in the paleorecord. For example, there
have been several shifts in the Holocene where grasslands have been
replaced by woody vegetation. … There is growing realization that
semiarid rangelands may be pushed beyond a threshold … that is not
reversed by a return to favorable conditions.”
Preparing
for Climate Change also points out that the Colorado Plateau,
particularly northeastern Arizona, contains the largest
concentration of sand dunes in the United States. These dunes have
been stabilized by vegetation for centuries. Researchers are
concerned that higher evaporation rates and extended drought periods
may reactivate these dunes. Active dunes are constantly on the move,
shifting with the winds and covering roads, farms, homes and other
structures.
“The
biggest impacts of active sand dunes in the Colorado Plateau
Region,” says Preparing for Climate Change, “would be on the
Navajo and Hopi Indians, whose reservation lands are either on, or
downwind of, the largest areas of dunes. … Many Navajo and Hopi
homes are on or near sand dunes. Sheep and cattle are important to
the economy of the Navajo and Hopi, and much of the vegetation
required for grazing is dune vegetation. In addition, dry farming is
practiced in much of the area, some of it on sand dunes. Thus,
reactivation of sand dunes in the area would have serious impacts on
living conditions, grazing and farming.”
Climate
change will also be hard on regional wildlife populations. As the
Southwest warms, much wildlife will instinctively desire to move to
higher-altitude areas where cooler and moister conditions prevail.
In earlier eras, wildlife migration was a simple process. Today,
however, migration corridors have frequently been severed by human
development, leaving isolated land fragments with trapped wildlife
populations. These ecological “islands” slowly lose their
biodiversity as species go extinct within their boundaries. This
loss of biodiversity will only be exacerbated by climate change.
Increased
droughts and flooding will also impact human health by spreading
disease. El Niño winters cause explosions in rodent populations,
leading to outbreaks of diseases like Hantavirus and Bubonic plague.
Flooding spreads mosquito-borne diseases and increases the
likelihood of water contamination from chemical, human and animal
wastes. Droughts increase the likelihood of dust-borne disease
outbreaks such as Valley Fever. Droughts will also increase soil
erosion, leading to an increasing frequency and severity of dust
storms, with a resultant decrease in regional air quality.
Climate
change is also expected to increase stress on our regional
electrical grid.
Preparing
for Climate Change says, “Electric power is extremely important
for growth and development in the Southwest. Throughout the region,
electricity is used to pump water from underground reservoirs and
distribute it through highly developed water supply systems for
cities, mines and agriculture. Energy demand in the West is forecast
to grow by 1.7 percent per year, without considering climate change.
… If the frequency and duration of extremely hot summer periods in
the Southwest increases, new power plants will be needed to supply
increased demands for cooling.”
At
the same time, however, coal-fired plants, which provide a
substantial percentage of electricity in the Southwest and account
for nearly 90 percent of utility carbon emissions, will come under
increasing pressure to lower their carbon dioxide emissions or shut
down altogether to prevent further global warming.
In
addition, hydroelectric plants like Glen Canyon and Hoover Dams will
continue to lose electrical generating power due to dropping water
levels. Furthermore, “High runoff events caused by sudden spring
warming can force reservoir operators to spill stored water and
forego saving that water for later power generation,” adds
Preparing for Climate Change.
“If
sufficient (electrical) reserve or “peaking” capacity is not
designed and built, electric service reliability is compromised and
brownouts and blackouts could result.
Climate
Action Report 2002
On
May 28, the Bush Administration published U.S. Climate Action
Report 2002 —Third National Communication of The United States of
America Under the United Nations Framework Convention on Climate
Change in fulfillment of its commitment under the Climate
Convention.
“Based
on his Cabinet’s review and recommendation, President Bush
recently announced a commitment to reduce greenhouse gas intensity
in the United States by 18 percent over the next decade through a
combination of voluntary, incentive-based, and existing mandatory
measures. This represents a 4.5 percent reduction from forecast
emissions in 2012, a serious, sensible, and science-based response
to this global problem,” contends the report.
The
President ’s National Energy Policy addresses “expanded
nuclear power generation; improved energy efficiency for vehicles,
buildings, appliances, and industry; development of hydrogen fuels
and renewable technologies; increased access to federal lands and
expedited licensing practices; and expanded use of cleaner fuels,
including initiatives for coal and natural gas. Tax incentives
recommended in the NEP and the President’s FY 2003 Budget will
promote use of renewable energy forms and combined heat-and-power
systems and will encourage technology development.”
The
Administration plans a “review of progress in 2012 to determine if
additional steps may be needed — as the science justifies — to
achieve further reductions in our national greenhouse gas emission
intensity.”
“The
above strategies are expected to achieve emission reductions
comparable to the average reductions prescribed by the Kyoto
agreement, but without the threats to economic growth that rigid
national emission limits would bring. The registry structure for
voluntary participation of U.S. industry in reducing emissions will
seek compatibility with emerging domestic and international
approaches and practices.”
In
fact, the U.S. would need a BEGIN ITALICS 24.3 percent END ITALICS
reduction from 2010 projections to meet the Kyoto Protocol. The
Kyoto Protocol is a set of binding emissions targets for developed
nations. It calls for a 7 percent reduction below 1990 greenhouse
gas emissions for the United States. The emissions targets include
all six major greenhouse gases: carbon dioxide, methane, nitrous
oxide, and three synthetic substitutes for ozone-depleting CFCs that
are highly potent and long-lasting in the atmosphere.
To
read more about the Climate Action Report, visit www.epa.gov/globalwarming/publications/car/index.html
Cities
can reduce greenhouse gas emissions
Local
governments need not wait for the Bush Administration to come to its
senses, however. There is much that cities and counties can do on
their own to reduce greenhouse gas emissions. One nonprofit helping
municipalities is Cities for Climate Protection. The Cities for
Climate Protection Campaign goal is to reduce greenhouse gas
emissions resulting from the burning of fossil fuels and other human
activities. CCP is a global campaign of the International Council
for Local Environmental Initiatives. More than 500 local governments
worldwide participate in the Campaign, including more than 125
cities and counties in the United States.
The
CCP campaign Web site says, “Local governments play a key role (in
reducing greenhouse gas emissions) because they directly influence
and control many of the activities that produce these emissions. The
CCP Campaign is an opportunity for cities and counties to take
practical steps which reduce greenhouse gas emissions and generate
multiple benefits for their communities.
“Local
governments own, operate, or influence:
-
Local
government facilities and operations such as municipal
buildings, street lighting, recreation facilities, wastewater
treatment plants
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Building
codes and permits that determine the energy efficiency of
residential and commercial buildings
-
Landfill
sites and the production of methane emissions
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Waste
collection and management including recycling, compost or waste
reduction programs
-
Land
use planning and development that determine the density, mixture
and physical layout of buildings, neighborhoods and communities
-
Transportation
infrastructure that determines the transportation choices of
residents and businesses, affecting the level and type of
transportation energy consumed and the number and length of
vehicle trips
-
Public
works infrastructure such as water supply, sewage, and other
public works
“Cities
and counties in the Cities for Climate Protection Campaign pledge to
reduce greenhouse gas emissions from their local government
operations and from throughout their communities. Each local
government sets its own emissions reduction target and develops a
Local Action Plan outlining actions that will be pursued to meet the
target. To participate in the Campaign, local governments pass a
resolution and undertake the following tasks or milestones:
-
A
base year emissions analysis of the sources and quantity of
greenhouse gas emissions
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A
forecast of emissions growth for the target year of 2005 or 2010
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Adoption
of an emissions reduction target, such as the "Toronto
Target" — reducing CO2 emissions 20 percent below 1990
levels by the target year, 2010
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An
action plan outlining the activities that will be pursued to
achieve the emissions reduction target
-
Implementation
of the actions
The
International Council for Local Environmental Initiatives
www.iclei.org/us/US_ccp.html
United States Office
15 Shattuck Square, Suite 215
Berkeley, California, USA 94704
Phone: 510-540-8843
Fax: 510-540-4787
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