Intensifying Drought Shifts Toward Central U.S.

Last week saw a major increase in drought intensity in the Central U.S. as flash wildfires sparked across Oklahoma. Meanwhile, longer term drought trends remained strong even as the U.S. West Coast saw breaks in the dryness in the form of late winter precipitation.

(Drought expanded across the Central U.S. last week as precipitation deficits there increased. Image source: Drought Monitor.)

A return to severe to exceptional drought across the Western and Central U.S. was one of the hallmarks of the overall warm winter of 2017-2018. Historic drought, which had been suppressed by substantial rains during 2016-2017, appears to have returned — with threat of worsening conditions through spring, summer and fall.

In the Central U.S., the dry pattern reinforced this week which added to already serious conditions. During mid-week, Oklahoma saw the eruption of seven large brush fires as a result of both drought and strong winds sweeping across the plains states. Dry springs can result in fires for this region. However, the recent intensification of droughts brought on by human-caused climate change is spiking fire hazards from the Central U.S. through the West Coast and beyond.

(California snow pack totals remain well below average despite a recent increase in the number of storms affecting the state. Image source: CDEC.)

In California, snow packs are still running well below average, despite a recent wave of storms sweeping through the region. But it’s worth noting that though still much diminished from typical snow depth totals, the present range is now higher than the driest years — 2014-2015 and 1976-1977. So the situation isn’t looking quite so bad as it was a few weeks ago.

In addition, the blocking ridge that had dominated the West for much of the winter has mostly collapsed — allowing more rain and snow-bearing storms to cycle through. Some relatively intense precipitation is expected to fall over central and northern parts of the state later this this week. However, with widespread drought reasserting and with warmer than normal temperatures likely this spring, the increasingly drought-prone state is far from out of the woods.

(Temperatures have tended to remain above average across most of the U.S. this winter even as abnormally dry conditions impacted the Southwest. Image source: NOAA.)

Under human-caused climate change increasingly warm temperatures result in higher rates of evaporation from lakes and soils. This increases drought intensity for many locations around the world. In keeping with this longer-term trend, the winter of 2018 can still be characterized as both warmer and drier than normal for most of the U.S. But the overall drought pattern has shifted more toward the Central U.S. and away from the West Coast with the approach of spring.



After a Brief Respite, Climate Change Enhanced Drought is Returning to the U.S.

Unseasonable warmth across the American West and overall dry conditions across the South is causing drought to expand throughout many parts of the United States.

According to the U.S. Drought Monitor, most of the southern half of the United States is presently experiencing abnormally dry or drought conditions. Meanwhile, an intense drought that has remained in place over the Dakotas and Montana for multiple months continues to persist.

Severe drought conditions are now present in the south-central U.S. with exceptional and extreme drought expanding through Arkansas, Oklahoma, Texas, Louisiana and Missouri. Deepening drought in California and Texas are notable due to the fact that Southeast Texas recently experienced record rainfall due to Hurricane Harvey and California experienced a very wet winter and spring period from 2016 to 2017. Somewhat milder drought is also spreading through the Southeast.

Re-expanding Southern California drought is also enhancing record wildfire activity in that state.

Much Warmer than Normal Temperatures

A strengthening La Nina in the Equatorial Pacific is helping to generate a drought tendency for the Southern U.S. However, various climate change related features including above normal temperatures and a persistent high pressure ridge in the West are lending intensity to the rising drought regime.

(U.S. 30 day average shows much warmer than normal conditions for the lower 48 with extreme warmth prevalent over the American West. Image source: Global and Regional Climate Anomalies.)

Over the past 30 days, temperatures for the U.S. as a whole have been 1.52 C above average (see image above). Much of this excess heat has been concentrated over the West, with mountain and Pacific regions seeing between 4 and 5 C above average temperatures.

Excess heat of this kind helps to speed the drying of soils and vegetation by increasing the rate of evaporation. A condition that can lead to flash drought — whose incidence has been expanding in lock-step with the human-forced warming of the globe.

A Ridiculous Ridge

Linked to the western heat and drought is a strong and persistent high pressure ridge. One that has hit a very intense 1041 hPa pressure as of Monday afternoon over the U.S. Mountain West.

(Very intense high pressure ridge over the U.S. west is presently locking in both warmer than normal and drier than normal conditions. Image source: Earth Nullschool.)

Persistent ridging of this kind was a key feature of the recent 2012 through 2017 California drought. Some climate studies have identified a tendency of these kinds of strong western ridges to form as Arctic sea ice recedes. And during the past decade, strong high pressure ridges have been a rather consistent and significant climate feature for the U.S. West. It is also notable that formation of more powerful ridging features during the fall and winter help to strengthen the Santa Ana winds — which fan California wildfires.

Present drought is nowhere near as intense as it has been during recent years. Especially in California which during 2017 has experienced a bit of a respite. However, with La Nina gaining traction in the Pacific, with global temperatures now in a range between 1.1 and 1.2 C above 1880s averages, and with persistent ridging again taking hold over the U.S. West, the risk of a return to intense drought — especially for the Southwest — is increasing.


With Temperatures Hitting 1.2 C Hotter than Pre-Industrial, Drought Now Spans the Globe

Jeff Goodell, an American author and editor at Rolling Stone, is noted for saying this: “once we deliberately start messing with the climate, we could inadvertantly shift rainfall patterns (climate models have shown that the Amazon is particularly vulnerable) causing collapse of ecosystems, drought, famine and more.”

We are in the process of testing that theory. In the case of drought, which used to just be a regional affair but has now gone global, Goodell appears to have been right on the money.


According to a recent report by the World Meteorological Organization, the Earth is on track to hit 1.2 degrees Celsius hotter than pre-industrial temperatures during 2016. From sea-level rise, to melting polar ice, to extreme weather, to increasing numbers of displaced persons, this temperature jump is producing steadily worsening impacts. Among the more vivid of these is the current extent of global drought.

The Four-Year Global Drought

During El Nino years, drought conditions tend to expand through various regions as ocean surfaces heat up. From 2015 to 2016, the world experienced a powerful El Nino. However, despite the noted influence of this warming of surface waters in the Equatorial Pacific, widely expansive global drought extends back through 2013 and farther.


(The Global Drought Monitor finds that dry conditions have been prevalent over much of the globe throughout the past four years. For some regions, like the Colorado River area, drought has already extended for more than a decade. Image source: SPEI Global Drought Monitor.)

In the above image, we see soil moisture deficits over the past 48 months. What we find is that large sections of pretty much every major continent are undergoing at least a four-year drought. Drought conditions were predicted by climate models to intensify in the middle latitudes as the world heated up. It appears that this is already the case, but the Equatorial zone and the higher latitudes are also experiencing widespread drought. If there is a detectable pattern in present conditions, it is that few regions have avoided drying. Drought is so wide-ranging as to be practically global in its extent.

Widespread Severe Impacts

These drought conditions have noted impacts.

In California alone, more than 102 million trees have died due to rising temperatures and a drought that has lasted since 2010. Of those, 62 million have perished just this year. Drought’s relationship to tree mortality is pretty simple — the longer drought lasts, the more trees perish as water stores in roots are used up. California has, so far, lost 2.5 percent of its live trees due to what is now the worst tree mortality event in the state’s history.


(It’s not just California. Numerous regions around the world show plants undergoing life-threatening levels of stress. In the above map, vegetative health is shown to be moderately stressed [yellow] to severely stressed [pink] over broad regions of the world. Image source: Global Drought Information System.)

The California drought is just an aspect of a larger drought that encompasses much of the North American West. For the Colorado River area, this includes a 16-year-long drought that has pushed Lake Mead to its lowest levels ever recorded. With rationing of the river’s water supplies looming if a miraculous break in the drought doesn’t suddenly appear, states are scrambling to figure out how to manage a worsening scarcity. Meanwhile, reports indicate that cities like Phoenix will require executive action on the part of the President to ensure water supplies to millions of residents over the coming years, should conditions fail to improve.

Further east, drought has flickered on and off in the central and southern U.S. In the southeast, a flash drought has recently helped to spur an unseasonable spate of wildfires over the Smoky Mountain region. Yesterday, at Gaitlinburg, TN, raging flames fed by winds ahead of a cold front forced 14,000 people to evacuate, damaged or destroyed 100 homes, and took three lives.


(Siberian wildfires burning on July 23, 2016 occur in the context of severe drought. Image source: LANCE MODIS.)

In the upper northern latitudes, the primary upshot of drought has also been wildfires. Wildfires are often fanned by heat and drought in heavily forested regions that see reduced soil moisture levels. Thawing permafrost and reduced snow cover levels exacerbate the situation by further reducing moisture storage in dry regions and by adding peat-like fuels for fires.

From Alaska to Canada to Siberia, this has increasingly been the case. Last year, Alaska experienced one of its worst wildfire seasons on record. This year, both heat and drought contributed to the severe fires raging around the Fort McMurray region in Canada. And over recent years, wildfires running through a tremendously dry Siberia have been so extreme that satellites orbiting one million miles away could detect the smoke plumes.

Drought and wildfires in or near the Arctic justifiably seem odd, but when one considers the fact that many climate models had predicted that the higher northern latitudes would be one of the few major regions to experience increases in precipitation, that oddity turns ominous. If the present trend toward widespread Arctic drought is representative, then warming presents a drought issue from Equator to Pole.

A dwindling Lake Baikal — which feeds on water flowing in from rain and snow in Central Siberia — bears grim testament to an expanding drought over central and northern Russia. Lake Baikal, the world’s deepest and oldest lake, is threatened by climate change-related drying of the lands that drain into it. In 2015, water levels in Baikal hit record-low levels, and over the past few years, fires raging around the lake have increasingly endangered local communities and wildlife.

To the south and west, the Gansu province of China was placed under a level 4 drought alert this past summerThere, large swaths of crops were lost; half a billion dollars in damages mounted. The Chinese government rushed aid to 6.2 million affected residents, trucking potable water into regions rendered bereft of local supplies.


(Lakes and river beds dried up across India earlier this year as the monsoon was delayed for the third year in a row. Image source: India Water Portal.)

India this year experienced similar, but far more widespread, water shortages. In April, 330 million people within India experienced water stress. Water resupply trains wound through the countryside, delivering bottles of potable liquid to residents who’d lost access. A return of India’s monsoon provided some relief, but drought in India and Tibet’s highlands remains in place as glaciers shrink in the warming air.

Africa has recently seen various food crises crop up as wildfires raged through its equatorial forests. Stresses to humans, plants, and animals due to dryness, water and food shortage, and fires have been notably severe. Earlier this year, 36 million people across Africa faced hunger due to drought-related impacts. Nearer term, South Africa has been forced to cull hippo and buffalo herds as a multi-year drought continues there.

Shifting north into Europe, we also find widespread and expanding drought conditions. This situation is not unexpected for Southern Europe, where global climate models show incursions of desert climates from across the Mediterranean. But as with northern Russia and North America, Northern Europe is also experiencing drought. These droughts across Europe helped to spark severe wildfires in Portugal and Spain in the summer, as corn yields for the region are predicted to fall.


(During November, drought spurred wildfires that erupted along the Amazon Rainforest’s boundary zone in Peru. Image source: LANCE MODIS.)

Finally finding our way back into the Americas, we see widespread drought conditions covering much of Brazil and Columbia, winding down the Andes Mountains through Peru, Bolivia, Chile, and Argentina. In sections of the increasingly clear-cut and fire-stricken Amazon Rainforest and running on into northeastern Brazil, drought conditions have now lasted for five years. There, half of the region’s cities face water rationing and more than 20 million people are currently confronted with water stress. From September to November 2015, more than 100,000 acres of drought-stricken Amazonian rainforest has burned in Peru. Meanwhile, Bolivia has seen its second-largest lake dry up and critical water-supplying glaciers melt as hundreds of thousands of people fall under water rationing.

Impacts to Food

Ongoing drought and extreme weather have created local impacts to food supplies in various regions. However, these impacts have not yet seriously affected global food markets. Drought in Brazil and India, for example, has significantly impacted sugar production, which in turn is pushing global food prices higher. Cereal production is a bit off which is also resulting in higher prices, though not the big jumps we see in sugar. But a Food and Agricultural Organization (FAO) Index for October of 2016 (173 approx) at 9 percent higher than last year’s measure for this time of year is still quite a ways off the 229 peak value during 2011 that helped to set off so much unrest around the globe.


(Rising food prices during 2016 in the face of relatively low energy prices and significant climate-related challenges to farmers is some cause for concern. Image source: FAO.)

That said, with energy prices falling into comparatively low ranges, relatively high (and rising) food prices are some cause for concern. Traditionally, falling energy prices also push food prices lower as production costs drop, but it appears that these gains by farmers are being offset by various environmental and climate impacts. Furthermore, though very widespread, drought appears to have thus far avoided large grain-producing regions like the central U.S., and central and east Asia. So the global food picture, if not entirely rosy, isn’t as bad as it could be.

Conditions in Context — Increasing Evaporation, Melting Glaciers, Less Snow Cover, Shifting Climate Zones

With the world now likely to hit 1.5 C above pre-industrial temperatures over the next 15 to 20 years, overall drought conditions will likely worsen. Higher rates of evaporation are a primary feature of warming, meaning more rain must fall just to keep pace. In addition, loss of glacial ice in various mountain ranges and loss of snow cover in drier Arctic and near-Arctic environments will further reduce river levels and soil moisture. Increasing prevalence of extreme rainfall events versus steady rainfall events will further stress the vegetation that aids in soil moisture capture. Finally, changes to atmospheric circulation due to polar amplification will combine with a poleward movement of climate zones to generally confuse traditional growing seasons. As a result, everything that relies on steady water supplies and predictable weather patterns will face challenges as the world shifts into a state of more obvious climate change.


Global Drought Monitor

Global Drought Information System



India Water Portal


The World Meteorological Organization

Hat tip to ClimateHawk1

Hat tip to June

Hat tip to Ryan

Hat tip to Griffon

Hat tip to Suzanne

Hat tip to Cate

Hat tip to Colorado Bob

Hat tip to Greg


California Drought To Enter 6th Year, Colorado River States Struggle to Avert Water Crisis, Southeast Drought Worsens

Around the world, global warming is starting to have a serious impact on rainfall in the subtropics and middle latitudes. The tropical atmospheric circulation known as the Hadley Cell is expanding toward the poles. This expansion is causing clouds and storms to move further north. And as a result, regions in the middle latitudes are starting to dry out.

According to The World Resources Institute:

A changing climate means less rain and lower water supplies in regions where many people live and much of the planet’s food is produced: the mid-latitudes of the Northern and Southern hemispheres, including the U.S. Southwest, southern Europe and parts of the Middle East, southern Africa, Australia and Chile.

Such a fundamental shift in global weather patterns due to human-caused climate change is expected to reduce the food and water security of numerous nations. The World Resources Institute recently warned that food and water crises were imminent as a result. And, apparently, these kinds of changes to the world’s weather are already generating profound shocks in parts of the U.S.

Colorado River and California Droughts Expected to Persist

For the Colorado River, this combined warming and movement of clouds northward has produced a 16-year-long drought. Hotter average seasons result in greater rates of evaporation. So even if rainfall averages remain, grounds, lands and rivers are drier. But the Hadley Cell’s expansion has also moved rain bearing weather systems north.

It’s a compounding drying influence that has pushed Lake Mead, the nation’s largest reservoir, to record low levels. And states dependent on the great river’s water supply for farming and industry are now involved in negotiations to avert a water crisis in 2018. Forecasts predict a 50 percent possibility that Lake Mead’s water levels will fall below its mandatory rationing line. Such an event would result in water cut-offs for Arizona and Nevada.


(Over recent years, the U.S. has experienced numerous severe and long-running droughts. These worsening drought conditions have impacted everything from Colorado River levels to wildfires, to the health of forests, to commerce on the Mississippi River, to the productivity of state agriculture. As human fossil fuel burning continues, atmospheric changes will force rainfall toward the poles which will tend to further worsen drought conditions in middle-latitude regions like the lower 48 states of the U.S. Image source: Drought Monitor.)

In an attempt to prevent crisis in the coming months, California and other Colorado River states are attempting to cut water consumption now. Such a planned regional belt-tightening would help to avert conflict over the Colorado River’s dwindling stores and smooth out any losses over time. But, sadly, climate conditions are only likely to continue to worsen — increasing the risk of mandatory rationing for 2019, 2020 and beyond.

In California, a five-year-long drought that is the worst in state history now threatens to enter its 6th year. Rains during 2016 did help to reduce the severity of drought conditions for some parts of the state. And during recent days, a series of Pacific storms has helped to deliver moisture to some northern and central regions. However, with record warmth settling in over the Arctic and with a La Nina developing in the Pacific, long range forecasts indicate a high risk that California will experience a warm, dry winter. Such predicted conditions would result in a persistence of the present drought with continued impacts to the state’s forests and agriculture.

Southeastern Drought Expected to Expand


(Drought conditions are expected to worsen across the US Southeast this fall and winter. Drought in the Colorado River region is expected to persist or worsen. Drought in California and in parts of the US Northeast is expected to persist. Image Source: Climate Prediction Center.)

Further east, a flash drought that has settled into the US south is expected to worsen over the coming months. Abnormal warmth in the range of 5-15 degrees (F) above average for the region during the past month has combined with dry weather to spur severe to extreme drought conditions over a six state area. Now, parts of Tennessee, North Carolina, South Carolina, Georgia, Alabama and Mississippi are under the gun — with drought zones expected to persist or expand through at least early February.

US Drought Conditions to Worsen as the Globe Warms

In total, more than 120 million people in the lower 48 states are experiencing drought. And the systemic impacts of multi-year, persistent droughts are widespread and growing. This drying is consistent with the impacts associated with a warming climate. And, unfortunately, such worsening of droughts is likely to continue until atmospheric warming is halted and/or reversed.


The Tropics are Pushing High Altitude Clouds Toward the Poles

As Clouds Head Toward Poles, it’s Time to Prepare for Food and Water Shocks

Drought Monitor

Climate Prediction Center

States Plan to Avert River Crash

Why is Southern California so Dry?

Droughts in California

Hat tip to Wili


Historic US Drought Still Ongoing; Isaac Brings Little Relief

The most recent report from the US Drought Monitor shows Isaac had little overall impact on this year’s historic drought. Areas in Arkansas, Missouri, and Indiana did receive substantial rains and farmers in those regions are experiencing much-needed relief. This year’s rains, however, have come too late for many crops.

Though drought conditions improved in these regions, overall US drought conditions remained severe.

In total, the land area currently experiencing drought remained at 63% of the contiguous United States for this week. The amount of area experiencing severe to extreme drought fell only slightly from 23% the week before to 22%.

Hard hit areas in the US, Europe and Russia have resulted in rising food prices this summer. However, this week, food prices stabilized even as the United Nations urged action to prevent hunger. The UN went so far as to say the world is not currently in a food crisis, but that conditions were very fragile and any additional stresses may push food markets over the edge.

Isaac’s rains may have provided some relief to farmers in states affected, but it has done little to alleviate low water levels on the Mississippi. River traffic is still severely constrained and is likely to become even moreso if rain conditions upstream do not improve. Sections of the Mississippi have been sporadically shut down to traffic since last month while up-river sections have been impassible since June.

The most recent ‘Drought Outlook’ does show some reason for hope. A large section of the heartland is expected to improve as new weather patterns emerge. Lower temperatures will also aid in moisture retention. However, a large area west of the Mississippi is expected to see persistent or intensifying drought. Overall, this forecast shows that the very large swath of drought should shrink a bit through fall, but that no major abatement is likely through late November.

Warmer than usual winter temperatures for the US are also likely to enhance drought in the areas in which these conditions persist. A return to El Nino conditions and a change in the blocking pattern could spell an abatement of current US drought conditions. However, this year’s expected El Nino has been rather weak and slow to develop.

Many climate scientists, including James Hansen, have attributed the severity of this year’s drought to human caused global warming. So as the underlying conditions of human caused climate change intensify, it is likely that potentials for droughts and severe droughts will continue to rise for the US in coming years and decades.


Cooler Temperatures Bring Little Relief From Intensifying Drought


Though cooler temperatures graced the mid-section of the country this week, the most recent report from the US Drought Monitor shows that the worst drought since 1956 continued to deepen over much of the country.

In total, more than 63% of the land area of the continental US suffered from drought conditions. This is an increase of 1% over last week’s drought report which showed 62% of the US mainland suffering from drought. Fully thirty percent of the US was suffering from extreme or exceptional drought, about the same levels as last week.

That said, beneficial rains in the Ohio valley resulted in slightly less farmland being gripped by drought. According to the Drought Monitor, 85% of the U.S. corn crop, 83% of soybeans, 63% of hay, and 71% of cattle areas are still experiencing drought. Though this number is a slight improvement, it is still a very large swath of US agriculture.

Other impacts from the ongoing drought this week included large regions affected by fires. California, Idaho, Oregon, and Washington all experienced large blazes. Idaho has experienced its worst fire year on record and so far the United States has seen the most area burned for this time of year. Fires continued to rage in far eastern Russia, but most Siberian fires are now currently contained. The Balkans also experienced a major outbreak of wildfires during an extreme heat wave that resulted in numerous heat deaths and temperatures soaring to well over 104 degrees in many places. Spain saw fires continue both on the mainland and on one of its islands. Greece saw a major wildfire engulf one of its islands as well.

The Mississippi river experienced sporadic interruptions of traffic with sections of the river shut down on Monday, Tuesday, and Wednesday of this week. Though the river has been running low throughout the summer, this is the first time that major traffic interruptions have occurred.

Worldwide, large areas of drought also affected the Balkan states, swaths of Europe, parts of India, and large sections of Asia.

The UN has recommended that nations begin setting up plans to deal with long-term droughts and the number of climate scientists linking the current droughts and extreme weather events to climate change continues to grow.


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