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Climate Change And Water Resources
THE IMPACT OF
CLIMATE CHANGE ON WATER RESOURCES
Climate scientists have been saying all along that one of
the primary effects of climate change is the disruption of the water cycle.
Since so much of everyday life and planning is determined
by hydrological systems, it is important to understand the impact that climate
change is having (and will have) on drinking water supplies, sanitation, food
and energy production.
Climate Change and
Water are Closely Linked
The relationship between water, energy, agriculture and
climate is as important as it is complex.
Climate change has the potential to tip out of balance
the relatively stable climate in which civilization has been built and
jeopardize the security of water, food and energy systems.
Over time, the effects of global warming due to the
human-generated buildup of greenhouse gases (GHGs) in the atmosphere have
become more evident.
In 2017, major GHGs, like carbon dioxide, methane and
nitrous oxide hit record levels.
The year’s carbon dioxide concentration reached a global
average of 405 parts per million,
which was the highest ever recorded. The top 20 warmest years on record
have come since 1995.
The year 2017, according to the NOAA State of the Climate in 2017 report, was the third
hottest year since the mid-1800s, and the hottest year ever without El Niño
warming the world’s waters.
As the earth’s average temperature continues to rise, we
can expect a significant impact on water resources with the potential for
devastating effects on these resources.
Water, the Climate Shark
One of the sharpest observations on
water and climate came from the 2009 launch of the CDP Water Disclosure
Project, which was aimed at global businesses, when the project’s CEO, Paul
Dickinson, stated that,
“Much of the impact of climate change will be felt
through changing patterns of water availability, with shrinking glaciers and changing
patterns of precipitation increasing the likelihood of drought and flood. If
climate change is the shark, then water is its teeth and it is an issue on
which businesses need far greater levels of awareness and understanding.” [emphasis added]
What’s true for business addressing climate change and
its water impacts is just as true for all segments of society; from government
agencies to water utilities to farmers to residential water users, every sector
must prepare for climate risk, especially as it relates to water.
In one influential academic paper, scientists proposed
that “stationarity is dead,”
which means that over time the expectation of a relatively stable climate and
narrow range of precipitation patterns are no longer assured.
This is a major paradigm shift because previous
assumptions on which decisions were made for long-term activities like building
dams and reservoirs and even short-term decisions like selecting crops to grow
in a given region, might now be too unreliable for predictable planning.
Below are some of the chief water-related challenges that
climate change will force people to contend with in the United States and
around the world.
Precipitation Pattern Shifts: Drought and
Deluge
Climate change disrupts the water cycle and
precipitation.
According to scientists from the Intergovernmental Panel on Climate
Change (IPCC), “[i]t is likely that anthropogenic influences have
affected the global water cycle since 1960,” and such effects are the
increased likelihood of more intense droughts and
precipitation events.
With higher average temperatures and warmer air that can
hold more water, a pattern might emerge of lengthy dry spells interspersed with
brief but heavy precipitation and possible flooding.
The back-and-forth between precipitation extremes is
sometimes described as “drought and deluge” or more
recently, “precipitation whiplash.”
CLIMATE
CHANGE AND DROUGHTS
Droughts, intense rains and
floods occur naturally and involve many factors, including geography, but
climate change can exacerbate these events.
For instance, temperature rise leads to greater
evaporation rates and plant transpiration, which results in water loss in soil
and plants.
For example, a Stanford study showed
that when higher temperatures coincided with minimal precipitation during the
California drought of 2011 to 2017, drought conditions worsened.
That drought is now considered
one of the more exceptionally dry and extreme in the state’s history.
North America is just a few years removed from the 2012-2013 drought that
impacted much of the continent, which turned out to be one of the most severe,
multi-state droughts in decades.
CLIMATE
CHANGE AND EXTREME PRECIPITATION
Recent research has tied certain extreme precipitation
events to the fingerprints of climate change.
Several studies concluded that climate change created
conditions that made torrential rainfall more likely, leading to several recent
devastating flooding events, for example, Hurricane Florence in North Carolina
in 2018 and Hurricane Harvey over southeastern Texas in 2017.
Research suggests that climate change could have boosted
the odds of the downpours in 2016 in Baton Rouge.
Water-related extreme weather events have huge costs in
terms of loss of life, wrecked infrastructure and economic damage even if
climate change’s influence on these extreme weather events cannot be always be directly
attributed, the influence remains.
Since tracking began in 1980, of the top four most economically costly US weather and
climate disasters, three are water-related:
1.
tropical cyclones (hurricanes) at $870.2
billion;
2.
droughts at $241 billion;
3.
severe storms at $219 billion; and
4.
inland flooding at $123 billion.
Water Tower Drawdown: Melting Glaciers and
Snow Drought
Sometimes called natural “water towers,” mountains
are critical headwaters to numerous rivers and other freshwater sources.
In all, mountain meltwater and runoff provide more
than 50 percent of the world’s freshwater.
Yet as global temperatures elevate, mountain glaciers and snowpack are melting
at an unprecedented rate.
Many mountain glaciers are in retreat, and some in
locations like Glacier National Park, are
in danger of disappearing within the 21st century.
If glaciers melt away, they can’t be restored. Thus,
areas that previously depended on glaciers for freshwater will then have to
seek other sources.
Further complicating mountain water storage capability is
the greater likelihood that warmer temperatures make precipitation fall as rain
rather than snow, sometimes called “snow drought.”
Although more rain than snow may seem like a plus, it
could mean reduced water availability.
When snow and ice collect on mountaintops, the snowmelt
releases water slowly – to streams, rivers and reservoirs – throughout the
spring and summer.
On the other hand, when rain falls on mountaintops,
especially during the winter, water runs off and quickly fills reservoirs to
capacity, which can result in excess water runoff that can’t be stored.
Because rain flows faster than melting snow, levels of
soil moisture and groundwater recharge may be reduced.
Areas that rely on meltwater as their primary freshwater
source could increasingly experience water shortages, especially towards the
end of summer, and will have to seek other sources.
Another consideration is that treating and moving public
water supplies (sometimes vast distances) requires large amounts of energy
which is produced mainly by burning fossil fuels like coal, natural gas and
oil.
That energy production, in turn,
requires massive amounts of water, thereby creating a loop of water use and
greenhouse gas emissions that further contribute to climate change.
Greenhouse Gas Emissions
Overall, greenhouse gas emissions must be decreased to
prevent climate change and protect threatened water sources.
Addressing big sources of GHG emissions is the place to
start, which means how and where energy is used is critical.
In total, the energy sector emits the vast majority of
greenhouse gases – at 72 percent – in the form of electricity generation,
transportation, manufacturing and so forth.
When it comes to emissions related to food, meat and
dairy have both a big climate footprint and water footprint. Worldwide, meat production generates 14.5 percent of
total greenhouse gas emissions.
Climate Change and Algal Blooms
Numerous other relationships between climate change and
water exist. For instance, climate change has warmed up water bodies and caused
harmful algal blooms to become greater problem in rivers, lakes and oceans in
the US and around the world.
These naturally occurring algal blooms are supercharged
by nutrient pollution –
worsened by drought and deluge cycles –
and warmer waters.
Excessive amounts of nutrients act as fuel for toxic
algal blooms that arrive there as heavy precipitation washes more nutrients
into waters.
These blooms, like blue-green algae, can
damage aquatic life and can produce toxins that are dangerous for humans and
other animals to touch or drink.
Florida in 2018 has experienced terrible harmful algal
blooms both in freshwater (blue-green algae) and in marine waters off the coast
(red tide), which has cost the state economically.
These events can hurt the economy and human health by
polluting drinking water, hampering tourism and shutting down fisheries and
shellfish harvesting.
FIND
YOUR WATER FOOTPRINT
AND LEARN HOW TO SAVE WATER
AND LEARN HOW TO SAVE WATER
Your water footprint includes the water you
use from a tap plus the “virtual water” used to produce the food you eat, the
products you buy and the energy you use. This virtual water makes up most of
your water footprint.
With increasing strain on water resources,
it’s important to learn how you use water in different parts of your life. You
can also find the best tips to show you how to save water. And check out
our Water Footprint Calculator to
find out your personal water footprint.
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