A large portion of the west U.S. was under the grip of an Drought that is unrelentingSince early 2020. Record-breaking rainfall has coincided with the dryness. WildfiresLong-lasting, intense and lasting Heat waves, Low stream flowsAnd Reservoir water supplies are decliningThe region has millions of people who rely on it.
The summer is upon us. OutlookIt is quite grim. The National Weather Service’s The latest seasonal outlookMay 19, 2022: A statement that drought is still a problem in most of the West and parts the Great Plains described it.
One of the drivers of the Western drought is persistent La Niña conditionsSince the beginning of the Summer 2020. During La Niña, cooler tropical Pacific waters help nudge the jet stream northward. This tends to bring about a change in the jet stream. There are fewer storms in the southern tier of U.S.Southwest droughts can be severe.
The OtherPerhaps the most important part of the story is the A rapidly warming climate makes it hotter and more thirsty..
As a climate scientist, I’ve watched how climate change is making drought conditions increasingly worse – particularly in the western and central U.S. The temperatures have been more than 2 degrees Fahrenheit (1.1 Celsius), higher than average in these regions over the past two years. Large swathes of the Southwest have seen temperatures exceeding 3 F (1.7 C) in recent years. Studies suggest the Southwest’s ongoing 20-year droughtBased on how dry the soils were, this is the worst drought in at least 1,200 Years.
A hotter atmosphere absorbs more moisture from soil
A thristier atmosphere tends extract more water from the soil. It causes it to worsen evaporative stressespecially if the region is experiencing lower-than-normal precipitation. High evaporative stress can quickly deplete soil moisture, leading to higher temperatures. Evaporative cooling effectThis causes a decrease in growth. This hydroclimatic stress can cause plants to wither, dry out, and even die.
The U.S. Southwest has seen an 8 percent increase in evaporative demand as a result of a warmer climate since the 1980s. This trend is generally understood. This is happening in other parts the country.
The This is a more relaxed atmosphereIt is transforming what might otherwise be dry or near-normal conditions into severe or extreme droughts. As the climate heats up, the increasing atmospheric thirst will only increase drought stress. This will have severe consequences for water availability and long-lasting, intense heat stress.
Climate models predict bleak prospects for the future Arider climates and severe droughts are more commonIn the Southwest and the southern Great Plains in coming decades.
These regions will see an increase in droughts and heat. There are fewer stormsAnd More days without precipitation. Climate models consistently project an a Poleward shift in midlatitude storm tracksAs the planet heats up, this century will see fewer storms in southern tiers of the country.
Even in the wettest areas, flash droughts are possible
The changing nature of droughts is a concern Even in areas of the U.S. where there is expected to be a net rise,In the 21st Century, there has been a significant increase in annual precipitation. A hotter future could lead to significant droughts due to the high evaporative demands on the land. These areas can experience prolonged periods of below-normal precipitation for many weeks to months, even though the overall trend is for more precipitation.
For example, large parts of the northern Plains have experienced precipitation. Increase of 10% or moreThe last three decades. The region is susceptible to severe drought in hotter climates.
The tail end of the what was the wettest decadeThe northern Plains were the only region to record this. A severe flash drought in the summer 2017.This resulted in agricultural losses of more than $2.6 billion. WildfiresSurrounding millions of acres Record evaporative demandThe flash drought was exacerbated by a severe short-term shortage of precipitation. A flash drought can be defined as a drought that lasts for more than one day. In a matter of weeks, the intensity increases rapidlyIt often surprises forecasters. The possibility of flash droughts that can can have severe consequences for agriculture and ecosystems, and can promote large wildfiresExpected to IncreasingWith a warmer and thirstier environment
In the Northeast, flash droughts are becoming a growing concern. New England was home to an estimated 12% of the 2020 drought. Extreme hydrologic droughtThe drought was severe, with low stream flows, groundwater levels and widespread crop loss between May and September. The drought developed quickly from the above-normally wet conditions due to very warm and dry atmosphere conditions.
As humanity enters a hotter future it will be more concerning to experience prolonged periods of below-normal precipitation for weeks or months.
Heading into unfamiliar territory
Other types of droughts are also on the horizon.
Atmospheric heat is a problem Snow droughtsSnow melts earlier if there is more rain than snow. Warmer temperatures result in shorter snow seasons, and longer growing seasons. Modifying the timing and frequency of ecological responses.
Land is Greening up earlierThis can lead to an earlier loss of water on the land surface. evapotranspiration – the loss of water from plants and soil. This could lead to soils that are drier in the second half of the growing seasons. This could lead to dry soils in the western and central U.S. Both future greening and drying will be more frequentThey are seasonally distinct across the growing season.
We are entering an era of rapid change in the climate. unfamiliar territory. New ways will be needed in the world To better anticipate future droughtsThis could lead to a transformation NaturalAnd Human systems.