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Megadrought in the western U.S. is the worst in at least 1,200 years

The lush, green forests of West Virginia are a world away from the arid landscapes of the American West. But the effects of a devastating “megadrought” in the U.S. are a stark reminder of the complex ways our planet’s ecosystems are connected. Researchers at West Virginia University are studying this severe weather event to understand it better.

Persistent U.S. megadrought

Typical droughts might last for a season or a few years, causing hardship and stress. A megadrought extends its impact across multiple decades. The ongoing megadrought in the Western U.S. began in the year 2000.

Shockingly, it has been going on for 23 years. An entire generation has grown up with the constant pressures of water scarcity.

This crisis has far-reaching consequences:

  • Plants and wildlife adapted to arid conditions reach their limits. Landscapes may change permanently, as some species die out and those better suited to the new conditions move in.
  • Farmers face difficult choices. Crops may fail, raising food prices. Land might need to be taken out of production entirely, affecting livelihoods and communities.
  • Reservoirs shrink to critical levels. Cities and towns might enforce water restrictions or face the possibility of their water supplies running out.
  • Wildfires become more frequent and intense due to dry conditions. Dust storms can increase, damaging crops and harming air quality. In some areas, the ground subsides (sinks) when too much groundwater is pumped out.

Scientists are urgently working to gather the data needed to understand the megadrought’s effects on the land, water resources, and communities that depend on them. This knowledge is the first vital step in identifying solutions, creating water management strategies, and building resilience for an uncertain future.

Decoding the U.S. megadrought

The landscape itself holds the key to understanding the severity and impact of the megadrought. Dr. Kannenberg from the WVU Eberly College of Arts and Sciences and his team use a suite of scientific tools to uncover these hidden secrets:

Tree rings

Each ring in a tree’s trunk marks a year of growth. Wide rings signal plentiful water, whereas narrow rings speak of drought. By analyzing tree rings from ancient trees, scientists can reconstruct a climate record extending back centuries.

The data reveals the current megadrought is the most severe the region has experienced in at least 1,200 years, a sobering benchmark for the challenges the West faces.

High-tech weather stations

Eddy covariance flux towers are advanced instruments that go far beyond simple weather monitoring. These towers act like the ecosystem’s stethoscope.

They measure how much water evaporates from the soil, how much is taken up by plants and released to the atmosphere, and how much comes down as rain. This detailed water budget reveals which areas are hardest hit by drought.

Moreover, these towers quantify the exchange of carbon dioxide between the land and the atmosphere. Plants absorb CO2 during photosynthesis, reducing its concentration in the air. Tracking this “breathing” cycle helps scientists understand if drought is crippling plants’ ability to act as carbon sinks.

Soil and groundwater

The land beneath our feet doesn’t just hold clues, it paints a stark picture of the crisis happening below the surface:

  • Soil moisture: Sensors measure the water content of the soil, revealing how deep plants must send their roots to survive and which areas are becoming too parched to support life.
  • Groundwater: Groundwater is a crucial water supply in times of drought. Wells act as windows into the dwindling aquifers, signaling when these vital reserves are dangerously low and highlighting the potential for long-term damage.

This multifaceted approach allowed Dr. Kannenberg’s team to build a clearer picture of the megadrought’s effect on plants – from individual trees to entire ecosystems – and the precious water resources that support them.

Impact of megadrought beyond U.S.

“Globally, megadroughts are projected to increase in frequency and severity in the coming decades.” explained Dr. Kannenberg. This is not a problem the West faces alone.

The data gathered in this research will help scientists understand what other regions, even those not currently considered dry, might face in the future.

Drought conditions limit a plant’s ability to perform photosynthesis, the process of using sunlight to convert carbon dioxide (CO2) into energy. Adequate water is essential for plants to open their stomata (tiny pores on leaves) and access the CO2 they need. During drought, plants often close their stomata to conserve water, sacrificing their ability to “inhale” CO2.

Carbon capture

This has a significant impact on carbon capture. With generally plentiful rainfall, trees in the East have a consistent water supply. This enables them to act as reliable carbon sinks, steadily removing CO2 from the atmosphere and storing it as wood and other plant tissues. This plays a role in mitigating climate change.

Arid landscapes naturally support less dense vegetation, meaning even without drought stress, they store less carbon overall. However, drought further reduces their already limited ability to photosynthesize and absorb CO2. In extreme drought years, carbon capture may cease almost entirely in some areas.

Even while droughts drastically limit their immediate carbon capture potential, desert and dryland plants do still play a role in the global carbon cycle, though the dynamics of this are less understood than in wetter regions.

“Dryland ecosystems in particular are really important for determining how much carbon gets taken up by the whole Earth’s surface globally,” Dr. Kannenberg explained. It’s less about how much they store at once, and more about how unpredictable they are, making our ability to model future climate change harder.

Study significance

As the Earth warms, dry areas will likely become drier, and droughts will be worse. “Historically, megadroughts are a rare, rare thing, but there have been a number of them throughout time, and they’re going to get more frequent and more severe in the future,” said Dr. Kannenberg.

While the scope of the problem is daunting, knowledge itself is a form of preparation. Understanding how the West’s plants, soil, and precious water resources are responding to this megadrought creates a roadmap for what other regions may face.

This research has the potential to guide smarter land management, water use policies, and hopefully, ease the impact of future droughts worldwide.


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