Water Around the World

Climate change is a problem that is affecting people and the environment. Greater energy efficiency and new technologies hold promise for reducing greenhouse gases and solving this global challenge. Climate change has enormous effects on our water supplies as well as water around the world. Here we examine Climate changes effects on drought, precipitation, and storms.


Drought is often defined as a prolonged period of dry weather caused by a lack of precipitation,
which results in a serious water short- age for some activity, group, or ecological system. Drought can also be thought of as an imbalance between precipitation and evaporation.

As average temperatures rise because of climate change, the Earth’s water cycle is expected to speed up, increasing evaporation. Increased evaporation will make more water available in the air for precipitation. On the other hand it will also take away more water that it usually does from a certain biosphere. As a result, storm- affected areas are likely to experience increased precipitation and increased risk of flooding, while areas located far from storm tracks are likely to experience less precipitation and increased risk of drought. Since the 1970s, drought-affected areas have increased on a global scale—more likely than not as a result of climate change caused by human activities.

There are many definitions and types of This chart shows the percentage of U.S. lands classified under drought conditions from 2000 through 2009. The data cover all 50 states plus Puerto Rico.

Drought conditions can affect agriculture, water supplies, energy production, and many other aspects of society. The impacts vary depending on the type, location, intensity, and duration of the drought. For example, effects on agriculture can range from slowed plant growth to severe crop losses, while water supply impacts can range from lowered reservoir levels to major water shortages. Lower stream flow and ground water levels can also harm plants and animals, and dried-out vegetation increases the risk of wildfires.


Precipitation can have wide-ranging effects on human life and ecosystems. Rainfall, snowfall, and the timing of snow- melt can all affect the amount of water available for drinking and irrigation, and can also determine what types of animals and plants (including crops) can survive in a particular place. Changes in precipitation can disrupt a wide range of natural processes, particularly if these changes occur abruptly and plant and animal species do not have time to adapt. This will in turn cause certain species to die off in specific areas.

This figure shows how the amount of precipitation has changed in different parts of the United States since the early 20th century (since 1901 for the lower 48 states; since 1905 for Hawaii). Alaska is not shown because of limited data coverage.

As average temperatures at the Earth’s surface rise, more evaporation and cloud formation occurs, which, in turn, increases overall precipitation. Therefore, a warming climate is expected to increase precipitation in many areas. However, just as precipitation patterns vary across the world, so will the effects of climate change. By shifting the wind patterns and ocean currents that drive the world’s climate system, climate change will also cause some areas to experience decreased precipitation.


Hurricanes, tropical storms, and other intense rotating storms fall into a general category called cyclones. There are two main types of cyclones: tropical and extratropical. Tropical cyclones get their energy from warm tropical oceans, while extratropical cyclones form outside the tropics, getting their energy from the jet stream and from temperature differences between the north and the south, often involving cold fronts and warm fronts. This indicator focuses on tropical cyclones in the Atlantic Ocean, Caribbean, and Gulf of Mexico. Tropical cyclones are most common during the “hurricane season,” which runs from June through November. The effects of tropical cyclones are numerous and well known. At sea, storms disrupt and endanger shipping traffic. When cyclones encounter land, their intense rains and high winds can cause property damage, loss of life, soil erosion, andflooding. The associated storm surge—the large volume of ocean water pushed ashore by the cyclone’s strong winds—can also cause severe flooding and destruction.

This figure presents annual values of the Power Dissipation Index (PDI). North Atlantic sea surface temperature trends are provided for reference. Note that sea surface temperature uses different units, but the numbers have been adjusted here to show how the trends are similar. The lines have been smoothed using a five-year weighted average.

Climate change is expected to affect tropical cyclone intensity by increasing sea surface temperatures, a key factor that influences cyclone formation and behavior. According to the U.S. Global Change Research Program, it is very likely that increased levels of greenhouse gases have contributed to an increase in sea surface temperatures in areas where hurricanes form, suggesting a human contribution to hurricane activity over the last 50 years. The U.S. Global Change Research Program and theInternational Panel on Climate Change project that tropical cyclones will become more intense, with higher wind speeds and heavier rains. These cyclones will potentially hit areas that are not prepared to handle such intense natural disasters. However, observations of past cyclone activity and projections of future activity have uncertainties because of changes in monitoring technology, longer-term regional climate pat- terns, and the limitations of climate models.

As global warming increases, more polar ice caps are melting, and thus inevitably, the sea level will begin to rise. Environmentalists predict that eventually the sea level will rise so drastically that many now densely populated coastal areas will be completely swallowed by the advancing water. We intend to examine water plans in Holland, where they have begun to tackle the issues that rising sea level will have on drainage and therefore CSO’s.

Table of contents:

o CSO in NYC
Combined Sewer System
Eliminating CSO

o Drinking Water in NYC
Buried Streams

o Holland

o Water Around the World

o PLANYC Initiatives

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