Background
A drought can be defined by an extended period of low precipitation, usually for a season or a bit longer, leading to in a shortage of water. Several factors indicate drought conditions, including low rainfall, high temperatures, reduced streamflow, lower ground and reservoir water levels, dry soil, and a smaller snowpack.
Drought and Climate Change
Droughts are becoming more frequent and severe caused by climate change in numerous areas, especially around the southwestern United States. These regions are expected to face more frequent, intense, and long-lasting droughts in the future.
How Climate Change Contributes
Warmer temperatures caused by climate change lead to increased evaporation, reducing surface water and drying out soils and vegetation. TThis indicates drier conditions originate from low rainfall bouts than in areas with lower temperatures. Climate change also affects the timing of water availability. For example, warmer winters cause less snow to fall in the Northern Hemisphere, particularly in regions like California’s Sierra Nevada.
A reduced snowpack is a problem even if overall precipitation remains the same. Many water systems depend on snowmelt in the spring to provide water. Snow also helps keep temperatures cooler by reflecting sunlight. Less snow leads to higher surface temperatures, worsening conditions. Some climate models predict that as temperatures rise, precipitation will become more erratic, leading to more extremes—both heavy rainfall and droughts. This unpredictability highlights the need for better water storage systems during dry years and increased protection from flooding during wet years.
Drier Regions Due to Climate Change
Some parts of the world are becoming drier due to climate change. In the Southwestern U.S., annual precipitation has been decreasing since the early 1900s, and this trend is expected to continue. While predictions about rainfall changes are less certain than those about temperature increases, scientists generally agree that wetter areas like the tropics and higher latitudes will get wetter, and drier places like the subtropics (home to most of the world’s deserts) will become even drier.
In some areas, droughts create a vicious cycle. Dry soils and sparse vegetation absorb more heat, forming high-pressure systems that prevent rainfall. This cycle makes already dry areas even drier over time.
Recent U.S. Droughts
The United States has seen some of its worst impact in recent decades. In 2012, 81% of the contiguous U.S. was experiencing at least abnormally dry conditions—the most widespread drought since the 1930s Dust Bowl. There was a lengthy drought throughout California from December 2011 to March 2019. In 2020, another extended incident hit, worsened by heatwaves in many Western and Central states, causing vegetation to dry out and fueling record-breaking wildfires. By December 2020, drought conditions had reached their worst since 2012, particularly in the West, where conditions worsened in 2021, especially in the Pacific Northwest, where record heat made the situation more extreme.
Threats Posed by Drought
The United States has historically been vulnerable, with major conditiuons occurring throughout history. Some notable examples include the Dust Bowl of the 1930s and the drought of the 1950s. These past events provide lessons as we face a future that is likely to be hotter and drier in certain regions.
Water Supply
The most obvious impact is reduced water availability. During droughts, communities may face limited access to water for daily needs like drinking, cooking, and cleaning, as well as for agriculture, transportation, and power generation. It can lead to higher water costs, rationing, and even the depletion of important water sources like wells. For example, a drought in 2021 caused wells in a rural California community to dry up, leaving residents without a reliable water supply.
Agriculture
It’s take a heavy toll on agriculture, affecting both livestock and crops like corn, soybeans, and wheat. In 2012, the U.S. Department of Agriculture declared a natural disaster in over 2,245 counties, or 71% of the country. Globally, hit several key food-producing regions that same year, contributing to food price spikes. In nations already dealing with food insecurity, these cost increases can lead to social unrest, migration, and famine.
Transportation
Low water levels in rivers caused by drought can disrupt commerce. For example, barges on the Mississippi River require at least nine feet of water to operate. In 2013, the U.S. Army Corps of Engineers had to dredge and remove obstacles from the river to maintain this depth. It is often accompanied by extreme heat, which can damage infrastructure by buckling roads, grounding airplanes, and warping public transit lines. Wildfires, which are often worsened, can also disrupt travel by closing roads, railways, and airports due to heavy smoke.
Energy
Droughts can affect electricity production, particularly at power plants that rely on water for cooling. Hydroelectric power is also less reliable during droughts. Heatwaves, which often accompany droughts, increase electricity demand as people rely more on air conditioning. This puts extra stress on the electrical grid, raising concerns about power reliability.
Public Health
Droughts have the potential for reducing river and stream flow, which can concentrate pollutants and endanger the quality of water used for relaxation and drinking. Drought-exacerbated wildfires generate smoke along with other pollutants that can affect communities nearby, particularly those with respiratory problems.
Economic Impact
The impacts are costly for individuals, businesses, and governments. From 2011 to 2020, the U.S. experienced nine droughts, each causing over $1 billion in damages. It’s also increase carbon dioxide levels in the atmosphere by reducing plant growth, which in turn limits the amount of carbon dioxide that vegetation can store. Wildfires and soil erosion, which are often linked to drought, release stored carbon back into the atmosphere.
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