The U.S. #drought vulnerability rankings are in: How does your state compare? — @NOAA

From NOAA (Alison Stevens):

If asked where in the United States is most vulnerable to drought, you might point to those states in the West currently suffering under hot and dry conditions and raging wildfires. However, according to a new NOAA-funded assessment, what makes a state vulnerable is driven by more than just a lack of rain: it’s a combination of how susceptible a state is to drought and whether it’s prepared for impacts. And the most and least vulnerable states could surprise you.

These maps show each state’s overall drought vulnerability (red) and how it ranks in the three individual categories that make up the score: sensitivity (blue), exposure (yellow-orange), and ability to adapt (purple). Darker colors show higher overall drought vulnerability and a greater degree of factors that increase the state’s vulnerability.

Sensitivity is the likelihood of negative economic impacts, which is based on the percentage of agricultural land, number of cattle, how much the state relies on hydropower, and recreational lakes. The exposure score reflects how often a state experiences drought and what assets, like the number of people and freshwater ecosystems, are at risk when it occurs. The ability to adapt score ranks how well the state can cope with and recover from drought, which depends on whether the state has a drought plan, how equipped it is to irrigate its land, and whether it is financially strong overall.

By this scoring system, the most vulnerable states are Oklahoma, Montana, and Iowa, while Delaware, Massachusetts, Connecticut, and California are least vulnerable to drought. Oklahoma gets its high vulnerability score from having an outdated drought plan and limited irrigation (low ability to adapt), as well as extensive agricultural activities and cattle ranching (high sensitivity). Despite facing recurring multi-year droughts (relatively high exposure), California ranks very low in drought vulnerability. Thanks to a strong economy and well-developed adaptation measures, it’s better prepared for an extreme drought when it occurs than most other states.

On the East Coast, the region is generally less vulnerable than other areas, given its wetter climate and lack of farming—except for New Jersey. As the most densely populated state in the country (very high exposure), it gets the region’s highest vulnerability score.

By breaking down drought vulnerability into three components, this assessment can help decision makers identify what makes their state vulnerable for better planning. And, as the study shows, even states that receive lots of rain can still be vulnerable.

Though drought is one of the costliest natural hazards in the United States, there are actions states can take to become more resilient.

This research was led by Johanna Engström, Keighobad Jafarzadegan, and Hamid Moradkhani from the University of Alabama and funded in part by NOAA’s Climate Program Office through its Modeling, Analysis, Predictions, and Projection (MAPP) program. The MAPP Program enhances our capability to understand, predict, and project variability and long-term changes in Earth’s climate system.

Bark beetle outbreaks benefit wild bee populations, habitat — @ColoradoStateU

A high-elevation spruce beetle-affected forest. Photo credit: Seth Davis via Colorado State University

Here’s the release from Colorado State University (Karina Puikkonen):

When southern Rocky Mountain forests are viewed from a distance these days, it may not look like much is left. Large swaths of dead, standing Engelmann spruce trees tell the tale of a severe regional spruce beetle epidemic in its waning stages. But among those dead trees, researchers have found good news. Zoom-in to the ground cover of these forests and there is life, even more abundant because of this disturbance.

New research led by Colorado State University and published online in Scientific Reports suggests that spruce beetle outbreaks may help create habitat for pollinator communities in wilderness settings. The research team found significant increases in floral abundance and wild bee diversity in outbreak-affected forests, compared to similar, undisturbed forest. Lead author Seth Davis said it may seem counterintuitive that landscape-level damage by one type of insect could still benefit another.

“Disturbances from bark beetles are typically regarded as undesirable for ecosystem function and human use,” said Davis, an assistant professor in the Forest and Rangeland Stewardship department. “But there is conservation value in post-outbreak forests; they appear to be the areas supporting more robust bee populations.”

This is good news for wild bee communities, which have been declining in recent years. The different bee species identified in this high-elevation study are made for harsh, cold environments. The fact that a natural disturbance can boost their presence is a boon to these rare, endemic creatures not found in warmer habitats. It’s also a benefit for these forests, because wild bees perform essential pollination services in ecosystems with very short growing seasons.

A blue vein trap at one of the study sites. Photo credit: Seth Davis via Colorado State University

A serendipitous observation

Davis regularly works in high-elevation forests. A few years ago, during another research project with department colleagues, he noticed a correlation between the number and diversity of bees observed, and the structure of the forest. He has since opened up this new thread of bee diversity research by combining it with his training in bark beetles.

“Disturbance studies on bees have primarily focused on fire,” said Davis. “There hasn’t been a lot of research looking at bee responses to beetle outbreaks.”

For this new study, his team developed a natural experiment, collecting parallel data in 28 beetle-affected and undisturbed alpine sites in north-central Colorado. They collected bees for two years at three different times across each growing season, and also recorded standard tree measurements and understory, or ground cover, plant data at the collection sites.

The team found that average floral abundance in spruce beetle-affected stands was 67 percent higher than in non-affected stands. The average number of bee species was also 37 percent greater in beetle-affected stands, with more species present in June than later in the growing season. Davis said the relationship between these insects and their surrounding vegetation may be more complex.

“It appears there are different controls over bee abundance and diversity,” Davis said. “Bee abundance was correlated to the floral species, while the diversity is more related to the forest structure, both of which are affected by bark beetles.”

In other words, bark beetles directly changed the forest structure which indirectly improved wild bee populations by providing a more robust food source for the buzzing insects on the ground.

Spruce beetle-affected forests offer a few advantages for understory plants and wild bees. Tree mortality typically opens up the forest canopy, allowing more light to reach plants and flowers on the forest floor. Dead trees also remain standing for up to 25 years after this disturbance. This offers more cavities for wild bees that nest in trees and dead wood.

Davis said he is interested in exploring this topic further to better understand these relationships over a longer time period and at a larger scale. As forests recover from outbreaks, he would like to see how long this benefit lasts. There is also the size disparity between small bee populations in one locale and the regional magnitude of these disturbances. It will be important to understand how well one small spot predicts these results at the landscape level.

While bees were captured for the purposes of this study, previous research has shown that the bee capture methods employed do not affect the overall bee community.

U.S. Winter Outlook: Cooler North, warmer South with ongoing La Nina — NOAA

Blizzard NW Chicago via NOAA.

From NOAA (Lauren Gaches):

NOAA’s winter forecast for the U.S. favors warmer, drier conditions across the southern tier of the U.S., and cooler, wetter conditions in the North, thanks in part to an ongoing La Nina. Forecasters at NOAA’s Climate Prediction Center — a division of the National Weather Service — are also closely monitoring persistent drought during the winter months ahead, with more than 45% of the continental U.S. now experiencing drought.

“NOAA’s timely and accurate seasonal outlooks and short-term forecasts are the result of improved satellite observations, more detailed computer forecast modeling, and expanding supercomputing capacity,” said Neil Jacobs, Ph.D., acting NOAA administrator. “From expansive and multi-hazard winter storms to narrow but intense lake effect snow, NOAA will provide the necessary information to keep communities safe.”

Currently, large areas of drought extend over the western half of the U.S., with parts of the Northeast also experiencing drought and near-record low stream flows. With a La Nina climate pattern in place, southern parts of the U.S. may experience expanded and intensifying drought during the winter months ahead.

“With La Nina well established and expected to persist through the upcoming 2020 winter season, we anticipate the typical, cooler, wetter North, and warmer, drier South, as the most likely outcome of winter weather that the U.S. will experience this year,” said Mike Halpert, deputy director of NOAA’s Climate Prediction Center.

This U.S. Winter Outlook 2020-2021 map for temperature shows above-average temperatures are likely in the South and below-average temperatures likely in parts of the North. (NOAA Climate.gov, using NWS CPC data)

Temperature
The greatest chances for warmer-than-normal conditions extend across the Southern tier of the U.S. from the Southwest, across the Gulf states and into the Southeast. More modest probabilities for warmer temperatures are forecast in the southern parts of the west coast, and from the Mid-Atlantic into the Northeast. Above-average temperatures are also favored for Hawaii and western and northern Alaska.

Below-normal temperatures are favored in southern Alaska and from the northern Pacific Northwest into the Northern Plains, with equal chances for below-, near- or above-average temperatures in the remaining regions.

This 2020-2021 U.S. Winter Outlook map for precipitation shows wetter-than-average weather is most likely across the Northern Tier of the U.S. and drier-than-average weather is favored across the South. (NOAA Climate.gov, using NWS CPC data)

Precipitation
Wetter-than-average conditions are most likely across the northern tier of the U.S., extending from the Pacific Northwest, across the Northern Plains, Great Lakes and into the Ohio Valley, as well as Hawaii and northern Alaska. The greatest chances for drier-than-average conditions are predicted in the Southwest, across Texas along the Gulf Coast, and in Florida. More modest chances for drier conditions are forecast in southern Alaska, and from California across the Rockies, Central Plains and into the Southeast. The remainder of the U.S., including the Mid-Atlantic and Northeast, falls into the category of equal chances for below-, near-, or above-average precipitation.

This seasonal U.S. Drought Outlook map for November 2020 through January 2021 predicts persistent drought across much of the Western U.S. in the months ahead. (NOAA Climate.gov based on NWS CPC data)

Drought
Widespread, ongoing drought is currently in place across the western half of the continental U.S. as a result of the weak Southwest summer monsoon season and near-record-high temperatures. Drought is also present in parts of the Northeast, Ohio Valley, Hawaii and Alaska. The ongoing La Nina is expected to expand and intensify drought across the southern and central Plains, eastern Gulf Coast, and in California during the months ahead. Drought conditions are expected to improve in the northern Rockies, Northwest, New England, Alaska and Hawaii over the coming months.

Nearly Half of the U.S. Is in #Drought. It May Get Worse — The New York Times

From The New York Times (Henry Fountain):

The most widespread drought in the continental United States since 2013 covers more than 45 percent of the Lower 48 states, federal scientists said.

Nearly half of the continental United States is gripped by drought, government forecasters said Thursday, and conditions are expected to worsen this winter across much of the Southwest and South.

Mike Halpert, deputy director of the Climate Prediction Center, a part of the National Oceanic and Atmospheric Administration, said a lack of late-summer rain in the Southwest had expanded “extreme and exceptional” dry conditions from West Texas into Colorado and Utah, “with significant drought also prevailing westward through Nevada, Northern California and the Pacific Northwest.”

Much of the Western half of the country is now experiencing drought conditions and parts of the Ohio Valley and the Northeast are as well, Mr. Halpert said during a teleconference announcing NOAA’s weather outlook for this winter.

This is the most widespread drought in the continental United States since 2013, he said, covering more than 45 percent of the Lower 48 states.
“The winter forecast doesn’t bode well,” Mr. Halpert added. Warmer and drier conditions are expected across the South and Southwest and drought is likely to develop in parts of Georgia and Florida and in Central and Southern California, where the dry conditions could add to the risk of wildfire in what has already been a catastrophic year for fires in California.

But northern parts of the country may see some relief, with wetter conditions predicted across most of the north, said David Miskus, a NOAA drought specialist…

US Drought Monitor October 13, 2020.

The American Southwest has been mired in drought for most of the past two decades. Studies suggest that the region is experiencing an emerging megadrought, similar to some periods in the past 1,200 years, when droughts persisted for 40 years or longer.

Global warming has made drought worse, in the Southwest and elsewhere, scientists say, exemplifying a trend toward more extreme weather as the climate changes.

Mr. Halpert said the likelihood of worsening drought this winter can be linked to La Niña, which developed in August and is expected to persist at least through the winter.