The Hydrologic Cycle

One of the main ways water affects climate is through the hy-drologic cycle. The hydrologic cycle is the pilgrimage of water as water molecules make their way from the earth's surface to the atmosphere and back again.1 In the hydrologic cycle, water is constantly moving between different states (solid, liquid, and gas) and different sites on the earth (the ocean, the atmosphere, and the land). As an example of how the hydrologic cycle works, imagine a glass of water outside a home on a warm...

Benefits of Increased Rainfall

Increased rainfall over time would certainly cause a lot of damage in some regions. But it might have some benefits as well. Some climate models have shown dry areas of the earth getting even drier as the world warms. Frank Wentz's study discussed previously, however, suggested not only that rainfall would be higher than expected in wet areas, but that it would be higher than expected in dry areas as well. If this hypothesis is true, drought-plagued regions like the American Southwest might...

The Melting of Giant Ice Sheets

In thinking about the effect of ice melt on sea levels, scientists are especially concerned about two massive glaciers known as ice sheets, one in Greenland and one in Antarctica. The Greenland ice sheet covers .65 million square miles (1.7 million sq. km), and contains .68 million cubic miles (2.85 million cubic km) of ice. The Antarctic ice sheet is many times larger it covers more than 4.6 million square miles (12 million sq. km), and contains more than 6 million cubic miles (25 million...

The Vakhsh River and Climate Change

Tajikistan is a mountainous, land-locked country in central Asia. It borders Afghanistan, Uzbekistan, and Kyrgyzstan, and lies close to Pakistan. The largest river in Tajikistan is the Vakhsh. The Vakhsh originates in the southwestern, glacier-covered mountains of Kyrgyzstan, and it crosses the entire length of Tajikistan before joining with the Panj River to form the Amu Darya at the border of Tajikistan and Afghanistan. The Vakhsh is Tajikistan's major source of electricity. Five dams are...

Wave Power

Another way to harness water energy is by using ocean waves. Unlike tidal energy technology, wave energy technology is still mostly in the development phase. Thus, ocean-power systems now come in a staggering array of shapes, sizes and configurations, according to science reporter Sandi Doughton.4 For example, one wave energy system design involves a chamber open to the waves with a hole containing a turbine in the top. As the water in the chamber rises, air is forced out through the hole,...

The Ice Albedo Feedback Loop

Another important feedback loop is called the ice albedo effect. As noted above, albedo is the ability of a substance or a body to reflect sunlight. Ice and snow are white, which means that they reflect the sun's rays or, to put it another way, they have very high albedos. In fact, according to geographer Grant R. Bigg, ice and snow have the highest albedos of almost any natural sur-face.10 From 70 percent to 80 percent of the sunlight that strikes ice and snow is reflected back into space. The...

Tidal Power

Today hydropower usually is used to generate electricity rather than to generate mechanical energy directly, as with historical water wheels. One technology in contemporary use for doing this is tidal power. Tidal power harnesses the energy resulting from the ebb and flow of water that occurs as tides come to shore and retreat from it. The Severn estuary in Wales has a very large difference between high and low tides, and as a result a barrier across it could generate as much energy as eight...

Other Feedback Effects

Scientists wonder about several other types of feedback effects as well. For example, as temperatures warm, frozen ground in the Arctic will thaw. Partially decayed vegetation, or peat, which has been locked in the permafrost, will start to decay and release carbon dioxide into the atmosphere. This, in turn, might exacerbate global warming. At the same time, less permafrost would mean less frozen ground, and more places for trees to grow. Trees take in carbon dioxide, so more trees might have...

US Coastlines

Perhaps the chief worry in coastal areas is that sea-level rise will cause a loss of land especially loss of valuable wetlands. According to the Environmental Protection Agency, Coastal wetland ecosystems, such as salt marshes and mangroves (trees and shrubs that grow in salt-water habitats) are particularly vulnerable to rising sea level because they are generally within a few feet of sea level____Wetlands provide habitat for many species, play a key role in nutrient uptake, serve as the basis...

Hydroelectric Power Notes

University Corporation for Atmospheric Research, Water Levels Dropping in Some Major Rivers as Global Climate Changes, April 21, 2009. www.ucar.edu. 2. Quoted in University Corporation for Atmospheric Research. 3. U.S. EPA, Coastal Zones and Sea Level Rise, August 3, 2009. www.epa.gov. 4. Union of Concerned Scientists, Early Warning Signs of Global Warming Droughts and Fires, November 10, 2003. www.ucsusa.org. 5. Jessica Marshall, Global Warming Is Shrinking the Great Lakes, New Scientist, May...

The Ocean Absorbs Carbon

In addition to absorbing and distributing heat, the ocean also affects global warming by absorbing carbon dioxide. Carbon dioxide (CO2) is the main way in which humans contribute to global warming. The burning of fossil fuels puts a great deal of carbon dioxide into the atmosphere, trapping the sun's heat and raising temperatures on the earth. By taking carbon dioxide out of the atmosphere, therefore, the oceans slow the process of global warming. According to David Adam, the environmental...

Lake Chad Disappears

Lake Chad sits on the borders of Chad, Niger, Nigeria, and Cameroon in West Africa. It has long been an important source of fish and of water for irrigation. Soon, however, the people of the region may no longer be able to rely on Lake Chad. That is because the lake is disappearing. Since 1963, the surface area of Lake Chad has decreased from 9,562 square miles (25,000 sq. km) in 1963, to just 521 square miles (1,350 sq. km) in 2007. The dwindling of the lake has been catastrophic for those who...

Water Climate and Feedback Loops

The cycle, whereby more carbon dioxide in the atmosphere reduces the absorptive power of the ocean, thus increasing the amount of carbon dioxide in the atmosphere, is an example of a feedback loop. In general, a feedback loop is a situation in which one condition creates other conditions that reinforce the first. For example, imagine a student is late and hurrying to get out of the house, so he accidentally drops his keys in the toilet. Panicked, he stumbles and hits the handle, flushing the...

Hurricanes and Extreme Weather Events

As discussed briefly in Chapter 1, one of the most serious worries about rising temperatures is that they will not only increase rainfall and flooding, but that they may contribute to extreme weather events like hurricanes. The primary fear is that rising temperatures may warm the ocean's surface. University of California professor of geography Catherine Gautier, in her book Oil, Water, and Climate, explains that a hurricane is essentially a heat engine with the warm tropical ocean as its...

The Ocean Affects Climate

Even outside its role in the hydrologic cycle, the ocean has a major effect on climate. In particular, oceans can have a major impact on temperature, in part because water has a high specific heat. Specific heat is a measure of the amount of energy needed to increase the temperature of a substance by a set amount. So to say that water has a high specific heat is simply to say that it heats up (and cools down) more slowly than many other substances. The high specific heat of water should be...

The North Atlantic Current

One of the most important currents is the North Atlantic Current, which moves warm surface waters north toward the Arctic. When the current reaches northern latitudes, it gets cooler and denser, and sinks. Then it turns south, pulling deeper cold waters toward the equator. Eventually, in the south, the water warms, rises, and turns back north. The system as a whole essentially functions like a giant, ever-turning conveyor belt. The North Atlantic Current and the warm water it moves northward...

How Much Will Sea Levels Rise

Scientists believe global warming is very unlikely to cause an ice age. Another dangerous scenario that is often discussed, however, is a massive rise in sea level. In the documentary film An Inconvenient Truth, for example, Nobel Peace Prize winner and former U.S. vice-president Al Gore argues that melting ice sheets could cause a sea-level rise of 20 feet or about 6m in the near future.24 Gore presents a graphic showing inundated coastlines, and contends that this sea-level rise would cause...