How is Global Warming Impacting the Water Cycle? The Shocking Answer
The Earth is approximately 75 percent water. Water has been present and circulating for more than 3.8 billion years on the planet. The presence of water sets Earth apart from other planets. Water allows Earth to support life. Global warming is undoubtedly impacting the water cycle. Let’s break it down a bit.
Nearly 97 percent of all the water on the planet is in the oceans while frozen icecaps, glaciers, and perma-snow store about 2 percent of the water on Earth. The soil, groundwater, lakes, rivers, and streams contain approximately 2 percent. Only 1/1000 of 1 percent is vapor in the atmosphere.
Of that total, 78 percent of all precipitation happens over the ocean. This precipitation is the source of 86 percent of all evaporation. The cycle of rainfall and evaporation keeps the Earth’s temperature in balance.
What is the water cycle?
The water cycle is the process that water goes through as it circulates. It begins at the Earth’s surface and travels to the atmosphere before returning to the surface again. As the sun heats it, the water evaporates from rivers, oceans, and other bodies of water.
Once the water vapor reaches the atmosphere, it cools and condenses into cloud masses. From the clouds, the precipitation falls to the earth in the form of rain, hail, snow, or sleet.
This precipitation collects in the oceans, lakes, rivers, and streams. It also dampens the soil. In some cases, it creates runoff when the ground is not able to absorb the water. Runoff flow occurs when heavy rains have already saturated the earth. It can also happen in urban areas covered in cement or asphalt.
Some precipitation filters through porous layers of rock. This trickling water creates pockets of groundwater beneath the surface. Much of the runoff and groundwater eventually makes its way back to rivers. The rivers empty into the ocean. From there, the evaporation cycle begins once again.
The water cycle provides nearly 90 percent of the moisture in the atmosphere. Plants add the remaining 10 percent through the process of transpiration. Plants absorb water through their roots. They then release it from small pores on the underside of leaves which is transpiration.
Why is the water cycle important?
If the available water did not replenish itself, the planet would run out of clean water. Every living thing on Earth needs water to survive.
Remember that 1/1000 of 1 percent of water found in the atmosphere as water vapor? Although it seems small, that little bit has a significant effect on the planet’s weather and climate.
Water molecules generate heat when they change form. This process creates the droplets found in clouds. These droplets become precipitation. It then falls back to the Earth’s surface. Without water vapor, clouds would not form. Without clouds, rain would not fall. Without rain, plants would not grow.
Plants need clean water to grow. Anything that eats plants depends on plant growth. Organisms that eat meat from animals that rely on plants are also dependant on the water cycle.
Both saltwater and freshwater marine life need constant clean water circulation. Certain species of land animals are sensitive to changes in the quality or quantity of water. Without clean water, both plants and animals would die off.
Humans need a large quantity of clean water daily to survive. The human body is about 60 percent water. This precious liquid regulates body temperature and maintains bodily functions. Your eyes and mouth need constant hydration.
Water is essential in digestion and elimination. Water cushions your joints and protects your spinal cord. Inadequate water consumption causes dehydration. If you become dehydrated, vital systems in the body begin to shut down. If you go without drinking water for more than a few days, you will die.
Thus the water cycle impacts the weather and climate around the globe. The climate conditions, in turn, affect the ultimate survival or extinction of the planet.
How is Global Warming Impacting the Water Cycle?
Evaporation and precipitation happen all the time which keeps the total amount of water vapor in the atmosphere stable. If there were too much ocean evaporation, it would empty the oceans. If there were too little precipitation over land, it would cause drought.
Rising sea levels
Over the past 100 years, the ocean volume has been over-replenished causing the sea-level rise at a rate of about 1/8 of an inch per year. While that might not seem like much, during the 20th century the sea level has risen 17 centimeters.
The rise in sea-level is a result of thermal expansion and increased glacier melting. Thermal expansion occurs when water absorbs excess heat and occupies more space because water expands when heated. The ocean absorbs approximately 90 percent of the heat in the atmosphere.
An increase in flooding
The evaporation of ocean water increases as temperatures get warmer. There is more moisture in circulation resulting in extremely heavy rainstorms. Heavy rainfall has increased by 20 percent in the past century.
These fast and furious rainstorms do not give the soil enough time to absorb the water that falls, and excess water makes more runoff.
Higher sea levels cause storm surges to move further inland than they did before which means there is flooding in larger areas along the coasts.
Less snowfall in some areas
Since the lower atmosphere is warmer, more precipitation falls as rain in some areas, instead of snow. This is also problematic. Snow gives the soil a chance to soak up the moisture as it melts gradually. So, the ground doesn't get the moisture that it needs to promote plant life. This water does not refill groundwater pools either.
Global warming is also causing glacier melting. To give just one example, Alaska’s Muir Glacier retreated 7 miles from its position in 1941. By 2004 the glacier was more than 2,625 feet less thick than before. Just between 2003 and 2010, the total global ice mass lost was about 4.3 trillion tons (1,000 cubic miles). This excess water added about 0.5 inches (12 millimeters) to global sea levels.
Global warming is also affecting the seasons. Warmer temperatures in the Northern Hemisphere are causing earlier snow-melts. The water arrives much sooner than plants need it. As a result, the summer and fall seasons are drier. The growing season is substantially affected.
Rerouting of established waterways
The change in water availability affects soil moisture. In turn, it changes the flow direction of streams, rivers, and other runoffs. Changes occur in areas that before had enough water to maintain a healthy wet/dry balance.
Creation of more greenhouse gases
High levels of water vapor in the atmosphere increase global warming. Water vapor makes up about 80 percent of the total greenhouse gas content. Where there is more atmospheric water vapor, there is more global warming.
How are the changes in the water cycle recorded?
Changes in the water cycle are not just guesses. Scientists use a variety of tools to measure every aspect of the cycle, from cloud mass to soil moisture. Listed below is only a partial list of all the ways that scientists learn about the water cycle.
The Palmer Drought Severity Index (PDSI) keeps track of potential long-term drought areas. The Randolph Glacier Inventory (RGI) monitors ice volume and glacier mass. The CFE Unified Gauge-Based Analysis of Global Daily Precipitation collects rainfall information from over 30,000 stations around the world.
Earth-observation satellites currently monitoring the water cycle from space include:
- Aqua satellite has six observation instruments including the AIRS, AMSU, HSB, AMSR-E, MODIS, and CERES.
- CloudSat observes clouds and precipitation using radar.
- CALIPSO monitors how clouds form, evolve and affect weather.
- GCOM-W tracks water circulation changes.
- GCOM-C records climate changes.
- ICESat-2 measures ice sheet mass balance and cloud heights.
- GRACE records sea-level rise, polar ice-cap mass loss, and water storage change.
What do the changes in the water cycle mean for the future?
Predictive models generate future water cycle scenarios based on current and past information. Examining the data, scientists are concerned about the future of the planet.
Global warming is impacting the water cycle in ways that are harmful to life on Earth. Some of the following consequences are already noticeable. Scientists expect these trends to worsen as temperatures rise.
Changes in the water cycle will create large areas affected by continuous drought. Increasing evaporation will put even more water vapor in the atmosphere. The short, intense rainfall that results cannot be absorbed by the soil.
Dry soil will change runoff routes. New runoff patterns will dry up creeks, streams, lakes, and rivers. Huge sections of formerly sustainable areas will become desert wastelands.
Too much or too little rain kills off plant life. Areas that supported the growth of commercially produced crops before will not be able to continue doing so. As a result, there will be less food of this type available.
The rapid melting of glaciers brings sediment along with the freshwater. Sediment build-up will pollute many freshwater lakes, stream, and rivers.
Groundwater is another source of clean drinking water. Runoff rushes over the surface of the earth. Its rapid flow does not replenish the pockets of groundwater found beneath it. As the supply of potable water diminishes, wildlife and humans suffer.
As glaciers continue to melt, the sea level will continue to rise. The rise in sea level means that larger sections of coastal areas will flood.
Intense heavy rainfall will result in flash floods. These high-intensity floods will not be able to be contained by the usual runoff methods. They will damage property and reduce crop yield, creating more food shortages.
Earlier snowmelt will cause lower moisture levels in the soil. Lower moisture levels are a direct contributing factor for wildfire. Wildfires burn trees which release carbon dioxide into the air. The extra carbon dioxide adds to the greenhouse gases in the atmosphere. With more carbon dioxide global warming will increase even more.
Immature roots are not able to absorb the quantity of water that mature trees and shrubs can. So, heavy rainfall in wildfire-damaged areas will result in flash floods. Flash floods do not allow time for the soil to take in moisture. The soil remains dry, hindering plant regrowth.
Barren areas destroyed by wildfire take years to recover. During that recovery period, plants are unable to release water vapor through transpiration. The plant's inability to contribute water to the atmosphere will further unbalance the water cycle.
Hurricanes and tropical cyclones
Warmer ocean temperatures increase tropical storm wind speeds. They also increase the amount of precipitation that falls during the storm.
As the glaciers continue to melt, the sea level will keep rising. Each hurricane will affect more land area as a result. Some believe that the frequency of hurricanes and tropical storms will decrease. However, the intensity of each storm will increase. So more category 4 or 5 storms will form every year.
An ecosystem is dependent on the population and health of its flora and fauna. Global warming’s impact on the water cycle is causing habitat loss now. Habitat loss causes mass animal and vegetation extinction around the globe.
Many types of plant and animal life are dependant on the careful balance of the water cycle. Too little water in rivers prevents fish from spawning. Too much water and ground-nesting birds won’t hatch.
Wetlands, rainforests, tropical islands, and deserts support a vast variety of vegetation and animals. These environments will be negatively affected by changes in the water cycle.
Extreme Winter Weather
The warmer the surface water temperature is, the more likely the water vapor in the air will turn to snow. Large bodies of water are freezing later in the season. There is an increased amount of water vapor in the atmosphere. All these combine to create more snow.
The loss of sea ice in the Arctic has changed the jet stream pattern over the Northern Hemisphere. The new jet stream pattern brings colder temperatures. The result will be arctic temperatures and increased snowfall.
Hydropower Electricity Outages
Hydroelectric plants harness the movement of water to create electricity. As more glaciers melt, more sediment ends up in the river water. This sediment damages the turbines. The hydroelectric plants then cannot produce enough power to meet human demand.
As a result, we construct more hydroelectric plants to meet demand. Rivers dammed to feed the hydroelectric plants create reservoirs. Reservoirs take up a larger surface area than rivers. Reservoir waters are warmer and evaporate faster.
This increased rate of evaporation will add to the amount of water vapor in the air. More water vapor means more intense precipitation. Heavy rainfall brings more sediment into the runoff. More sediment in the water damages the turbines, leading to an endless cycle.
More Global Warming
Glaciers and snow reflect the sunlight and reduce the lower atmosphere temperature. As these melt, darker land replaces them which absorb light causing the temperature to rise.
The warmer it is, the faster water evaporates. The more water evaporates, the higher the temperature rises. Scientists estimate that the water cycle accelerates by 8 percent for every degree of surface warming.
More water vapor amplifies warming. Temperatures continue to rise, melting even more glaciers.
What Can You Do?
The impact of global warming on the water cycle are cyclic. It’s essential that these destructive circles stop. Perhaps then, the planet can begin repairing the delicate balance of the water cycle.
Reduce your use of fossil fuels.
Burning coal and oil has increased the carbon dioxide found in the atmosphere. Carbon dioxide is a contributing factor in what we know as the greenhouse effect which has caused global warming. Look for renewable energy alternatives such as solar or wind power.
Plants can absorb water and release water vapor through transpiration. Adding to this part of the water cycle will help balance it again. Plant vegetation native to your local environment. Native vegetation will create an agricultural ecosystem that is sustainable and self-sufficient. Permaculture will also provide habitat for local wildlife.
Petition your government to dismantle older, unused dams.
Reservoirs contribute the same amount of greenhouse gas emissions as the aviation industry.
Damming rivers impacts wildlife in the area. Fish that travel upstream to spawn are now unable to. The flooding from creating a reservoir destroys wetlands and other natural habitats. Dismantling unused dams will return the area to a productive, self-sustaining ecosystem.
Rivers provide natural flood protection. Dammed areas flood more often. Flooding causes more soil erosion. Soil erosion leads to more flooding. Allowing the river to flow freely will reduce the occurrence of flooding in the area. Less flooding means more freshwater and vegetation.
These may seem like small things to do in this global crisis. Your efforts can make a difference in the impact global warming has on the water cycle.