Scientists, industry experts, and investment fund managers look at how climate change may affect existing water resources.
In February 2007, researchers at
the Scripps Institution of Oceanography, University of California San Diego
reported they had produced the first clear evidence of human-produced ocean
warming. Working with colleagues at Lawrence Livermore National Laboratory’s
(LLNL) Program for Climate Model Diagnosis and Intercomparison, research marine
physicist Tim Barnett and climate scientist David Pierce established that
warming produced by climate modeling corresponded to actual ocean measurements
over the past 40 years with a confidence factor of over 95%. Efforts to explain
warming through naturally occurring climate variations or external forces, such
as solar or volcanic factors, didn’t come close to reproducing the observed
human-induced effect.
Barnett called the findings not
only “compelling evidence” of global warming, but also a clear demonstration of
the ability to simulate its past and, likely, future evolution. “One of the
models we used we also use for weather forecasting, and it turned out to be the
best by far in reproducing what has happened in the last 40 years,” he says. “My
position is we ought to believe it for the next 20 to 30 years at least. Even in
that time frame, we were able to show we basically have a train wreck here in
the West in terms of water and power production.”
As one aspect of the looming
crisis, the Scripps researchers predict that, given the expected climate change,
and with no future curtailment of water use, there is a 50–50 chance Lake Mead,
one of the two large reservoirs on the Colorado River water system, will be dry
by 2021, and a 50% chance that by 2017 water levels will be too low to generate
power.
The National Center for
Atmospheric Research describes climate change as any persistent change in the
statistical distribution of climate variables, with global warming as the
fundamental driver. Increases in carbon dioxide and other greenhouse gases have
caused radioactive heating that traps solar energy in the atmosphere, a trend
that’s expected to raise temperatures at the beginning of the next century as
high as 6.6˚C (12˚F) above 1990 levels.
The Scripps and LLNL scientists
are hardly alone in focusing on links between climate change and our water
resources. Examining the results of 19 climate models, Richard Seager, senior
research scientist at Columbia University’s Lamont-Doherty Earth Observatory,
established that warmer temperatures are producing increased uplift of air
masses in the earth’s tropics. The warm air cools as it rises, condensing and
producing increased tropical precipitation. If that’s not enough, more bad news
comes from the fact that the increased uplifted air warms as it descends over
already drought-prone regions, such as southern California and the American
Southwest. University of California Los Angeles professor Glen MacDonald carries
the scenario further, suggesting that we could be in for decades of hot, dry
weather, stretching from southern California north to the headwaters of the
Sacramento and Colorado rivers (California’s water lifelines)—a combination of
circumstances he describes as “the perfect drought.” MacDonald contends that
global warming replicates natural conditions that occurred during the Middle
Ages, particularly the 12th century, when a severe drought in southern
California, combined with persistent low flows in both the Sacramento and
Colorado rivers, produced a dry spell that lasted 60 years.
One of the practical challenges
facing water managers attempting to deal with the effects of warming, is that
current climate models are not precise enough to predict conditions at a
regional level. “The thinking is that the equatorial regions will be wetter and
the higher latitudes will likely be dryer,” says Jack Henderson, water supply
program director at Tetra Tech. “But, the temperate latitudes are more difficult
to predict.”
“The models agree substantially,
but they have a more difficult time agreeing on precipitation,” remarks Sujoy
Roy, a CA-based principal engineer for Tetra Tech. “In California, we definitely
have a pretty good understanding of what might happen. If temperatures go up,
for example, the snow pack will melt a few weeks earlier than normal. But, it’s
trickier in the Northeast, where some models predict more precipitation and some
less. The fact is that if you’re a water supply person, your main interest is
precipitation, so you need to keep track of what’s going on in the modeling
world, particularly in this regard, and understand how it’s evolving. With more
and more interest from the water resources community, there will be pressure on
scientists and model developers to produce better, and more defensible,
arguments for ways water managers might move in the future.”
Henderson adds, “Tetra Tech has
some of the most sophisticated models, but precipitation is one of the critical
inputs to river system hydrological models. We’re working on coming up with
better science-based tools to give us a better understanding of what kind of
precipitation we should load in the models. While it’s already a consensus that
we’ll see melting sooner in high mountain regions that rely on snow pack for
their water supply, we’re also going to see lower river flows earlier in the
summer and fall, which will make storage a key component in capturing runoff to
use in the dryer parts of the year. In coastal areas, precipitation is expected
to be more frequent and occur as exceptionally heavy storms. So again, the
question is how do we capture the amount of fresh water we need through flood
skimming or runoff capture for use during the dry periods, which are going to be
longer and more significant.”
Erik Straser, general partner at
Mohr Davidow Ventures, an early-stage venture capital firm in Menlo Park, CA,
says that a change in climate brings about unpredictability, and that
variability can be dangerous when it comes to water resource management. “The
infrastructure we’ve developed for serving water was built on a set of
presumptions about where the water is and when it comes,” he notes. “And if that
changes, our ability to actually harvest water and move it to where we want it
will be significantly impacted. We are already at this very interesting
intersection between the needs of a modern society and the world’s finite water
resources. Layer on climate change and you add both variability and risk.”
Piet Klop, Senior Fellow at the
World Resources Institute (WRI), looks at this from a worldwide perspective. “It
may actually be, that in some parts of the world, water is going to more a
critical issue than energy, because energy is still easy to move around,” he
acknowledges. “But there are parts of the world where we’ve settled millions of
people without having adequate water resources, like the American Southwest or
the northern plain of China. We’ve lived for a long time with the delusion that
we could engineer our way out of water scarcity. In China they’re doing it, but
at exorbitant cost. In most of the world, energy is more or less traded at
market prices. Nothing could be farther from the truth when you talk about
water, with the predictable result that it’s wasted. We’ve basically ignored the
whole issue and done stupid things, like growing Las Vegas and Phoenix.”
Seager sees the response to
climate predictions varying among water managers. “In New York City [NY], the
problem is related to intense rainfall events coming in increasing
frequency—brief, short downbursts that are flushing heavy organic loads into the
upstate reservoirs. This increase has been predicted by the models, and now the
water supply has been so affected by this increased organic intake, the water
managers can’t shut their eyes to the fact that something is happening.”
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Photo: Dr. Ken Dewey, Applied Climate Sciences, University of Nebraska, Lincoln |
| Lake Mead at Hoover Dam: According to researchers, the lake is 118 feet below maximum elevation. |
To provide a better perspective on
how climate change effects may actually play out, the Association of
Metropolitan Water Agencies (AMWA), a nonprofit organization of the largest
publicly owned drinking water systems in the US, commissioned a study evaluating
its implications. Among the report’s key conclusions is that, although the
leading edge impacts of climate change may already be apparent, the larger
effects on water supplies will be more evident as the century unrolls and will
continue for centuries to come. Secondarily, the report concludes that, despite
their efforts, the present generation of utility managers will not be able to
resolve the effects of climate change, but should, nonetheless, undertake
planning and research to aid their successors.
Among its major effects,
warming-induced climate change is expected to cause sea levels to rise, as
warmer temperatures cause the oceans to expand and glaciers and ice sheets melt.
As any number of experts have observed, warming will also accelerate the pace of
the hydrological cycle. Warmer temperatures will cause water to evaporate more
readily, causing the total amount of precipitation to increase on a global
level. The predicted temperature increases also suggest that areas subject to
drought may see more extensive drought and heat waves, while areas accustomed to
snowfall will see warmer and shorter winters, which have already been implicated
in reduction in the amount of water stored as ice in glaciers and seasonal snow
packs. The thought is that an earlier spring melt will also have significant
implications for downstream flows in late summer and early fall.
With increased rainfall frequency
will come severe flooding and pollution of freshwater supplies from wastewater
treatment, and storage and conveyance systems. The AMWA report notes that, for
the most part, existing wastewater treatment plants and combined sewer overflow
control programs have not considered climate change in their design. The result
could be continually increasing influent challenges from sewage overflows,
producing high concentrations of disease-causing Giardia,
cryptosporidium, and coliforms.
Changes in basic climate variables
such as temperature, rainfall, seasonal patterns, runoff characteristics, and
recharge patterns of both ground and surface waters are also likely to produce
significant baseline changes in the earth’s ecosystems, and, in turn, this could
impact existing negotiated in-flow requirements aimed at providing sufficient
cold water to sustain fish species or freshwater flows into estuaries, to
maintain tolerable levels of salinity during summer months or periods of
droughts.
So, what is there to do? AMWA’s
report identifies a need for additional scientific research, both to better
understand the impacts of climate change on existing fresh water resources and
to help develop and assess the affordability of alternative sources of supply
that include reuse, recycling, conservation, and desalination. In the applied
arena, AMWA Executive Director Diane VanDe Hei has called for increased federal
investment in water infrastructure to help offset the costs of developing new
sources of supply and finance capital projects.
“Total precipitation can stay the
same, even with overall drying, but the shift from snow to rain makes the water
storage problem more difficult,” says Seager. “What really needs to be done is
to work out what the implications are for water supply systems, such as the
Colorado River and the Sierras, although this is tough to accomplish, because
our current models don’t have the spatial resolution to capture individual river
basins. To get it all absolutely correct, you need to fully represent the
mountains. However, current grids are too course to accurately represent all the
topography in a place as complicated as the American Southwest.
“So, the prudent thing is to
assume that something like this is going to occur, create some scenarios, and
work out what can be done that makes sense,” he adds. “And, of course, that
means using water more wisely. California is the largest agricultural producer
in the nation, but only 1%, of the wealth the state generates annually, comes
from agriculture. So, growing alfalfa in the high desert may not be such a
sensible thing to do given the economic return relative to the economic return
on the movie industry, for example. If we could drop agricultural usage from 90%
to 80%, the water supply for people doubles.”
At Tetra Tech, Roy argues for
planning for a world “with less available freshwater resources” and notes with
satisfaction, a “fundamental philosophical shift” in the California Department
of Water Resources’ recognition that historical patterns of hydrology typically
used for water planning, are insufficient for a future that is likely to be
different from what’s occurred 50 to 100 years in the past. “There are other
benefits in planning for a world with less water,” says Roy. “One is lower
energy cost to treat and dispose of water, which is a benefit even if climate
change ends up providing more water than we have today.”
At the University of California
Santa Barbara’s Bren School of Environmental Science and Management, Water
Policy Program Director Robert Wilkinson advises water managers to acknowledge
the “fair certainty” for changes in the historic precipitation, that the
industry has engineered its systems to. “But instead of the water community
saying, ‘Modelers, tell us what the answer is,’ we have to establish how we’re
going to manage our resources under scenarios of increased magnitude events,
whether they’re drought or floods,” he says.
“Water efficiency offers a
first-order opportunity to build resilience and a more robust system,” he adds.
“All other things being equal, if we can take care of all of our needs with less
water, we’re less vulnerable. And, why not? In every sector around the country,
there are clearly opportunities. Efficiency is also good economics, and there
are other benefits, including environmental and efficiency improvements that
tend to take some of the pressure off certainly when we’re cycling into
conditions of low precipitation.”
Henderson argues that better
planning means adopting a local perspective. “We’re taking freshwater out of
smaller watershed basins in highly populated coastal areas, treating it for
drinking water, then shipping it to a regional wastewater treatment plant for
discharge either out-of-basin or directly into the ocean,” he says. “What this
does is circumvent the hydrologic cycle, to the degree that we have a river here
in Massachusetts that frequently dries up on an annual basis. So one of the
solutions is, rather than using water once and shipping it out of basin, we need
to use it and keep it local.”
Straser thinks technology will
provide answers. “I think we’re going to hear from the venture capital community
about the need for technology to support conservation and reuse, and to meter
out the resource we have,” he says. “Conservation, recycled water, and desal
will be three fundamental approaches to developing new sources of water, but the
priorities will differ depending on relative regional advantages, whether, for
example, you’re a net producer or a net exporter. Los Angeles is basically a
gigantic net importer, Lake Tahoe County an exporter. So each is going to have a
different view.”
Straser also agrees about the
importance of local orientation. “We’re going to have to make our water loop, so
to speak. If you’re Los Angeles, you can’t just be pulling water out of the
Colorado and rejecting it into Santa Monica Bay. You’re going to have to find a
way to locally recycle. And that’s going to involve some amount of pretreatment
and post-treatment, and probably some use of an aquifer or some other large body
to help recover or purify.”
“Water presents an absolutely
incomparable opportunity to invest money and earn an exceptional return,” says
Eric Pedersen, co-portfolio manager for The Water Fund, an investment fund
focused exclusively on water. “There have been comparisons made that water is
where oil was at the turn of the 20th century. I don’t know if I’d necessarily
go that far, but we think investing in water companies can provide sustainable,
long-term profitable opportunities.
“Water companies typically trade
at higher multiples of revenues and earnings than industrial companies, because
there’s a developing understanding that the growth prospects driven by water
scarcity, infrastructure rehabilitation, and regulatory compliance in the water
space is going to be much higher than general industrial growth,” he continues.
“And because the multiple is higher the evaluations are higher, which means that
as water companies generate income, it’s cheaper for them to raise capital. And
because it’s cheaper to raise, it can be used to solve water problems.”
Pederson also sees the value of
the local approach. “New communities are being set up where individual buildings
do their own water treatment,” he says. “Like anything else, it will start small
and catch on as the economics and social benefits become more apparent. Home RO
[reverse osmosis] has had problems, but GE has developed a product that doesn’t
require a storage tank. When you turn on the tap, the pressure pushes the water
through the RO unit—a good example of how technology is evolving to address
problems.”
“The way things are currently
established, you make money selling things,” Wilkinson says. “So, new
technology—new ways to develop water supplies and sell them—can obviously
translate into good business opportunities. One of the issues we worked long and
hard on in the energy arena over decades, was to develop ways to sell the
benefits of energy use efficiency and how one can structure markets, so there is
a profit to be made.
“Efficiency needs to be put on a
par in the marketplace,” he says. “Right now, we don’t have the institutional
structures, or legal structure, or a business model set up to take advantage of
that, but we need to think of efficient technologies as infrastructure and as
investment opportunities, so when we talk about our water infrastructure, it’s
all the way down through recycled to the devices in the home or business or
farm.”
Henderson notes an additional
challenge. “Certainly conservation and water efficiency is the first and most
practical step towards managing with less water,” he says. “But, a lot of
resource conservation is put on the backs of municipal water authorities
although agriculture and industry produce a much greater demand. Clearly there
has to be a more realistic balancing of these competing interests.”
“Drought and rainfall intensity is
just the most visual manifestation of climate change,” says Klop, from his
perspective at WRI. “But there are complicated relationships in the system such
as energy consumption and residential water use. The hotter it gets, the more
water people will use. The ultimate effect is they will also consume more power,
which will require more water. Right now 48% of water withdrawal in the US is
withdrawn for power generation, mostly to cool thermoelectric or even nuclear
plants.”
AMWA’s climate change impact
report suggests addressing warming’s impacts through a combination of
vulnerability assessments and long-term planning. The objective of vulnerability
analysis is to assess the degree to which current water resource development and
planning could be disrupted by near-term (20–50 years) manifestations of climate
change. The idea for long-term planning (in the mode of Integrated Resource
Planning, which many water utilities are already utilizing), is to adopt a broad
view that integrates all facets of the challenge managers are facing to keep a
wide range of options open and provide for maximum flexibility. The goal is to
adopt the broadest possible strategic view of how utilities can strategize and
plan to cope with long-term climate change, including the critical range of
environmental, socio-economic, and engineering factors.
What the scientists, Wall Street,
and current water management strategists all suggest is a portfolio approach
that affords a maximum degree of flexibility and resiliency. There’s no doubt
this will involve complex trade-offs between multiple objectives and multiple
constraints, and this will require elaborate stakeholder involvement.
Over a year ago, MacDonald
published an op ed piece in the Los Angeles Times, in which he called on southern
California water districts and planning bodies, in combination with state
officials and federal agencies, to systematically consider prolonged
scenarios related to climate change and develop a range of potential
strategies for managing our water resources.
Imagination, it seems, may be a place to begin addressing
what’s ahead of us.