Ecology, Climate Change and Related News

Conservation Science for a Healthy Planet

Archive: Jul 2016

  1. Wallasea Island, England—natural infrastructure restoration

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    Wallasea Island project takes significant step forward as sea walls breached

    Scheme will use 3m tonnes of excavated material from Crossrail tunnels to help create lagoons across an area of marshland twice the size of the City of London

    Caroline Davies the Guardian UK Sunday 12 July 2015 19.01 EDT Last modified on Friday 25 September 2015 11.10 EDT

    The creation of Europe’s largest man-made nature reserve, which will transform farmland into coastal marshland using material excavated during the Crossrail project, is one significant step nearer completion.

    Wallasea Island Wild Coast project is using more than 3m tonnes of material excavated from London to raise part of the Essex island by an average of 1.5m, to create lagoons across 670 hectares of farmland – an area more than twice the size of the City of London – and restore the marshland it once was 400 years ago.

    The first phase of the Royal Society for the Protection of Birds (RSPB) 20-year project was completed at the weekend, when new sea walls were successfully breached to allow for tidal flow into the marshland.

    Five hundred years ago, there were 30,000 hectares of intertidal saltmarsh, a crucial wildlife habitat and effective sea defence, along the Essex coast. Today, there are just 2,500 hectares….

  2. Climate Change Fingerprints Are All over California Wildfires

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    Climate Change Fingerprints Are All over California Wildfires

    Blazes have reportedly risen 500 percent on public lands since the late 1970s


    The Sand Fire burning in California’s Santa Clarita Valley in July. Credit: Kevin Gill via Flickr CC by 2.0

    Reports this week from the front lines of the Sand Fire in Southern California painted the scene as apocalyptic. The drought-fueled blaze was explosive, fast-moving and devastating, burning through 38,000 acres in the Santa Clarita Valley and forcing the evacuation of more than 10,000 homes.

    If the state’s wildfire season holds true to forecasts, the Sand Fire will be one of many catastrophic wildfires to scorch drought-stricken forests and shrublands across California this year. So far, only one wildfire has been larger — the 48,019-acre Erskine Fire, which started in June in the Sierra Nevada Mountains and destroyed 250 homes and buildings.

    None of the fires have been among the worst or largest wildfires the state has seen in recent years, but they’re part of a dire global warming-fueled trend toward larger, more frequent and intense wildfires. The number of blazes on public lands across the West has increased 500 percent since the late 1970s, said LeRoy Westerling, a professor studying climate and wildfire at the University of California-Merced.

    The outlook this summer is sobering: Wildland fire potential for most of coastal California and the Sierra Nevada Mountains is above normal and is expected to remain that way through October, according to the National Interagency Fire Center.

    The wildfire forecast follows a major heat wave in California, where the temperatures soared above 120°F (48.9°C) in some parts of Southern California. The region is seeing a significant warming trend. Each decade since 1970, average summer temperatures have warmed about 0.45°F (0.25°C).

    The worst of the fire season in Southern California may be yet to come, said Hugh Safford, a U.S. Forest Service ecologist based in Vallejo, Calif.

    “The most dangerous fire conditions occur from the end of September to December, when Santa Ana winds from the desert interact with the driest fuels of the season after five to six months of drying,” he said. “I would expect an active fire season, and critical conditions in the fall.”….

  3. Downtown L.A.’s five-year rain total is lowest ever recorded.

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    http://www.latimes.com/local/lanow/la-me-ln-la-dry-rain-season-future-20160706-snap-story.html

    Los Angeles TimesJul 07

    Los Angeles has chalked up yet another dreary milestone in its growing almanac of drought.

    On Wednesday, experts at the National Weather Service confirmed that the last five years have been the driest ever documented in downtown L.A. since official record keeping began almost 140 years ago.

    Downtown’s parched landscape mirrors the broader, historic drought that has wreaked havoc on California this decade. Forests and hillsides across the state are parched, brittle and burning.

    Nearly 3,000 firefighters are battling wildfires that have scorched more than 50,000 acres since June.

    But in Northern California, a series of winter storms, or “atmospheric rivers,” dumped feet of snow and inches of rain, replenishing reservoirs and building up the Sierra snowpack for a spring and summer melt.

    California may come to depend more on those “atmospheric rivers” in the future for its water and downtown Los Angeles and the surrounding cities may continue to miss out on them, said Michael Anderson, a climatologist with the Department of Water Resources.

    “The challenging part is how it translates into a representation of the future climate. Is that the future norm or the extreme? That’s really tricky to say,” Anderson said.

    But until that’s answered, Angelenos can expect more rainless days thanks to a developing La Niña, which brings a drier-than-average winter.

    “We’re still trying to figure out if this is a window into our future,” Anderson said.

  4. Dam good! Beavers may restore imperiled streams, fish populations

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    Dam good! Beavers may restore imperiled streams, fish populations

    Posted: 08 Jul 2016 11:49 AM PDT

    Using a first-of-its-kind, watershed-scale experiment, researchers demonstrate beaver dam analogs in the Bridge Creek Watershed of north central Oregon’s John Day Basin foster natural beaver activity, which benefits the area’s threatened steelhead trout population.….Billions of dollars are spent for varied river restoration efforts each year in the United States, he says, but little evidence is available to support the efficacy of beaver dams.
    “This may be due to the small scale of the limited research aimed at investigating restoration effects,” Bouwes says. “So, we conducted a large-scale experiment, where the effects of restoration on a watershed were compared to another watershed that received no restoration.”

    …..When Lewis and Clark made their way through the Pacific Northwest in the early 19th century, the area’s streams teemed with steelhead and beaver. But subsequent human activities, including harvesting beaver to near extirpation, led to widespread degradation of fish habitat. Bouwes says these activities may have also exacerbated stream channel incision, meaning a rapid down-cutting of stream beds, which disconnects a channel from its floodplain and near-stream vegetation from the water table. He notes beavers build dams in the incised trenches, but because of the lack of large, woody material, their dams typically fail within a year….Bouwes says. “It sets a chain of ecological effects in motion that result in habitat destruction, including declines in fish populations and other aquatic organisms.”

    To conduct the experiment, the researchers built beaver dam analogs, known as “BDAs,” by pounding wooden posts into the stream bed, and weaving willow branches between the posts, throughout the 32-kilometer study area. “Our goal was to encourage beaver to build on stable structures that would increase dam life spans, capture sediment, raise the stream and reconnect the stream to its floodplain,” Bouwes says. “We expected this would result in both an increase in near-stream vegetation and better fish habitat.” Beavers quickly occupied the BDAs, resulting in an increase in natural dam construction and longevity in Bridge Creek. “What really impressed us was how quickly the stream bed built up behind the dams and how water was spilling onto the floodplain,” Bouwes says.

    The researchers also documented increases in fish habitat quantity and quality in their study watershed relative to the watershed that received no BDAs and saw little increase in beaver activity. The changes in habitat in the watershed receiving BDAs resulted in a significant uptick in juvenile steelhead numbers, survival and production. “This is, perhaps, the only study to demonstrate beaver-mediated restoration may be a viable and efficient strategy to rehabilitate incised streams and to increase imperiled fish populations,” Bouwes says. “With so many streams that need help, we need to look towards more cost-effective and proven means to restore streams, and beavers may be able to do a lot of the heavy lifting for us.”

    —————————————

    Nicolaas Bouwes, Nicholas Weber, Chris E. Jordan, W. Carl Saunders, Ian A. Tattam, Carol Volk, Joseph M. Wheaton, Michael M. Pollock. Ecosystem experiment reveals benefits of natural and simulated beaver dams to a threatened population of steelhead (Oncorhynchus mykiss). Scientific Reports, 2016; 6: 28581 DOI: 10.1038/srep28581

  5. “Living Shorelines” Will Get Fast Track to Combat Sea Level Rise

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    “Living Shorelines” Will Get Fast Track to Combat Sea Level Rise

    Scientific American
    By Erika Bolstad, ClimateWire on July 6, 2016

    As sea levels rise along U.S. coasts, it may soon get easier for people and local governments to obtain federal permits to build what are known as “living shorelines,” natural or nature-based structures designed to protect communities and infrastructure from extreme storms and flooding even as they protect habitat. The
    Army Corps of Engineers is considering a new category to its nationwide permits that would allow speedier approval of living shorelines, which include wetlands with sea and marsh grasses, sand dunes, mangroves, and coral reefs.

    Currently, it’s much faster for property owners in many parts of the country to get a permit for sea walls, bulkheads and other so-called gray infrastructure than it is to get a permit for construction of nature-based systems.
    If the corps moves forward with the new category, though, permits to build living shorelines could be issued in as few as 45 days, instead of 215, a spokesman for the agency said. “The living shoreline piece is a part of what we’re pushing as a nonstructural, nature-based method that is a lot less costly,” said Lt. Gen. Thomas Bostick, who ushered in the proposed permit during his time as chief of the Army Corps of Engineers, before his retirement last week. “It helps us with our environmental focus; it helps us with the endangered species, perhaps. All of that is a natural way that we can reclaim some of our land and take the focus off of expensive infrastructure.”…

    A study by the Pew Charitable Trusts found that about 14 percent of the U.S. coastline is what researchers described as “armored.”
    A 2015 report from NOAA on living shorelines noted that if coastal populations continue to increase, and if so-called “shoreline hardening” continues at the current rate, nearly one-third of the contiguous U.S. coastline could have sea walls or other gray infrastructure by 2100
    .

    The agency found evidence that shorelines with intact natural coastal habitats not only see less damage but bounce back more quickly from severe storms.

    Studies have shown that living shorelines host greater populations of fish and other organisms crucial for shorebirds and for recreation and commercial fisheries, said Rachel Gittman, a postdoctoral research associate at Northeastern University’s Marine Science Center. Gittman, who spends much of her time in North Carolina, was asked by the Pew Charitable Trusts to analyze the effectiveness of natural shorelines compared to hard infrastructure. The work is part of the foundation’s climate adaptation efforts to improve flood readiness in U.S. communities….

    Some organizations are trying to quantify whether living shorelines cost less to build and can provide the same protection. The Nature Conservancy found a perfect opportunity in Miami-Dade County in South Florida, said Kathy McLeod, director of global risk reduction and resilience at the environmental organization.

    There, the county’s aging wastewater plant was under orders to stop dumping waste into the ocean. The Nature Conservancy is studying whether marshes surrounding the low-lying plant can help protect it from storm surge and flooding.

    The marshes aren’t just protection for the plant’s $3 billion in upgrades—they’re a part of the massive federal Everglades restoration project.

    The Nature Conservancy hopes that what it learns about the project will make it easier for other communities weighing similar projects to move forward with natural systems, McLeod said last week, speaking on a panel about climate adaptation and resilience at the same event as Bostick….

    …Despite the massive push for living shorelines, such natural systems may not be appropriate everywhere, Gittman said. But they do give communities options that might supplement hard infrastructure, Gittman said.

    “I think it would be naive to say you shouldn’t modify your shorelines, because obviously we’ve built along our shores. We have a lot of infrastructure and communities that we need to protect,” she said. “If you’re talking about a really urban area, you’re probably going to still need other structures for flood protection. Maybe there are places where a sea wall is the only option, maybe it’s a major port, so you really have to have a deep channel.”

    She’s working on a chapter of a book, along with engineers and landscape architects, ecologists, and other experts, that will help guide the private sector in designing the living shorelines of the future. Its message is that people can design shorelines that are more dynamic than static, she said.

    “What it means is that we need to be more creative in how we stabilize shoreline, and I think we also need to learn a bit more from nature,” she said. “We should be thinking about how to incorporate natural shore protection components. Anywhere where naturally stabilizing features can be incorporated—I think that’s what we need to be thinking about.”


  6. Action Needed Now for Climate Change Preparedness, Reinvestment Urged in Natural Defenses

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    Oct 24 2014

    Climate impacts are hitting home faster than governments are adapting, but it’s not too late to protect our communities with cost-effective, nature-based approaches for risk reduction, according to a new report from the National Wildlife Federation, Allied World Assurance Company Holdings, LG, and Earth Economics. Natural Defenses from Hurricanes and Floods: Protecting America’s Communities and Ecosystems in an Era of Extreme Weather takes an in-depth look at the growing risks we face from these potentially-catastrophic natural hazards, the policy solutions that can safeguard people, property and wildlife habitats, and local case studies that point the way forward. It calls on America to substantially increase our investments in proactive risk reduction measures at a “Marshall Plan” scale that takes into consideration the growing risks from more intense storms, flooding and sea level rise.

    …”There are obvious financial implications to the insurance industry as a result of extreme weather,” said Scott Carmilani, President and Chief Executive Officer of Allied World Assurance Company Holdings, AG.  “More importantly, insurance carriers need to partner with clients to help them mitigate their risk in the event of hurricanes and floods. It simply makes good business sense to confront this threat now and that’s why we’re working together with conservationists, industry partners and elected officials to find solutions.” The report analyzes a series of studies showing how taking action now can protect our communities and save money, highlighting how healthy natural systems such as dunes, oyster reefs, barrier islands and wetlands can reduce flood risk more effectively in many cases than erecting levees and seawalls. Among the examples:

    • Jamaica Bay prepares for strengthening storms: A broad coalition of federal, state and local agencies have restored more than 150 acres of wetlands, which held strong and helped absorb wave action during superstorm Sandy.
    • Duluth plans now for the next flood: In the wake of 2012’s flooding that caused $55 million in damages, Duluth worked with NOAA to conduct an economic benefit-cost study of natural infrastructure projects to reduce flood risks. It’s now applied for and received an Environmental Protection Agency grant to help fund a project that can naturally store 200,000 gallons of stormwater.
    • California’s Yuba County protects farms, cleans water and sustains wildlife: By moving 9,600 feet of levees further back from the shores of the Bear and Feather Rivers, Yuba County reconnected 600 acres of flood-prone agricultural land to the floodplain. This land has since been restored into habitat that supports numerous species of fish and wildlife, provides a variety of recreational opportunities, and helps buffer the release of pollutants from nearby agricultural operations into the rivers….

    ….This report identifies seven areas of federal and state law in need of improvement:

    1. Phase out subsidies for federal flood insurance to reduce incentives for development in high-risk and environmentally-sensitive areas while taking care to address social equity impacts.
    2. Prioritize federal investments on the front end of disasters, potentially reducing billions in disaster relief after storms and floods.
    3. Further reduce and eliminate federal subsidies that lead to more development on barrier islands.
    4. Ensure better protection of wetlands, intermittent streams, and other water bodies that can absorb floodwaters, act as speed bumps for storm surge, and buffer communities.
    5. Refocus Army Corps of Engineers on restoration projects
      that work with nature to reduce flood risk
      rather than on multi-billion dollar civil works construction projects.
    6. Ensure that state-sponsored insurance programs are designed in ways that discourage development in hazard-prone areas while protecting socially-vulnerable communities.
    7. Take urgent action to reduce carbon pollution that’s worsening extreme weather.
  7. ‘The Blob’ overshadows El Niño

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    ‘The Blob’ overshadows El Niño

    Posted: 06 Jul 2016 08:44 AM PDT

    New research based on ocean models and near real-time data from autonomous gliders indicates that the ‘The Blob’ and El Nino together strongly depressed productivity off the West Coast, with The Blob driving most of the impact.


    ‘The Blob’ and El Niño are on their way out, leaving a disrupted marine ecosystem behind. Credit: Michael Jacox

    El Niño exerted powerful effects around the globe in the last year, eroding California beaches; driving drought in northern South America, Africa and Asia; and bringing record rain to the U.S. Pacific Northwest and southern South America. In the Pacific Ocean off the West Coast, however, the California Current Ecosystem was already unsettled by an unusual pattern of warming popularly known as “The Blob.”

    New research based on ocean models and near real-time data from autonomous gliders indicates that the “The Blob” and El Niño together strongly depressed productivity off the West Coast, with The Blob driving most of the impact.

    The research published in the journal Geophysical Research Letters by scientists from NOAA Fisheries, Scripps Institution of Oceanography and University of California, Santa Cruz is among the first to assess the marine effects of the 2015-2016 El Niño off the West Coast of the United States.

    “Last year there was a lot of speculation about the consequences of ‘The Blob’ and El Niño battling it out off the U.S. West Coast,” said lead author Michael Jacox, of UC Santa Cruz and NOAA Fisheries’ Southwest Fisheries Science Center. “We found that off California El Niño turned out to be much weaker than expected, The Blob continued to be a dominant force, and the two of them together had strongly negative impacts on marine productivity.”

    “Now, both The Blob and El Niño are on their way out, but in their wake lies a heavily disrupted ecosystem,” Jacox said.

    Unusually warm ocean temperatures that took on the name, The Blob, began affecting waters off the West Coast in late 2013. Warm conditions — whether driven by the Blob or El Niño — slow the flow of nutrients from the deep ocean, reducing the productivity of coastal ecosystems. Temperatures close to 3 degrees C (5 degrees F) above average also led to sightings of warm-water species far to the north of their typical range and likely contributed to the largest harmful algal bloom ever recorded on the West Coast last year.

    “These past years have been extremely unusual off the California coast, with humpback whales closer to shore, pelagic red crabs washing up on the beaches of central California, and sportfish in higher numbers in southern California,” said Elliott Hazen of the Southwest Fisheries Science Center, a coauthor of the paper. “This paper reveals how broad scale warming influences the biology directly off our shores.”

    The research paper describes real-time monitoring of the California Current Ecosystem with the latest technology, including autonomous gliders that track undersea conditions along the West Coast. “This work reflects technological advances that now let us rapidly assess the effects of major climate disruptions and project their impacts on the ecosystem,” Jacox said.

    Separate but related research recently published in Scientific Reports identifies the optimal conditions for productivity in the California Current off the West Coast, which will help assess the future effects of climate change or climate variability such as El Niño. The research was authored by the same scientists at UC Santa Cruz and NOAA Fisheries.

    “Wind has a ‘goldilocks effect’ on productivity in the California Current,” Hazen said. “If wind is too weak, nutrients limit productivity, and if wind is too strong, productivity is moved offshore or lost to the deep ocean. Understanding how wind and nutrients drive productivity provides context for events like the Blob and El Niño, so we can better understand how the ecosystem is likely to respond.”

    Both papers emphasize the importance of closely monitoring West Coast marine ecosystems for the impacts of a changing climate. Although the tropical signals of El Niño were strong, the drivers — called “teleconnections” — that usually carry the El Niño pattern from the tropics to the West Coast were not as effective as in previous strong El Niños.

    “Not all El Niños evolve in the same way in the tropics, nor are their impacts the same off our coast,” said Steven Bograd, a research scientist at the Southwest Fisheries Science Center and coauthor of both papers. “Local conditions, in this case from the Blob, can modulate the way our ecosystem responds to these large scale climate events.”

    Story Source:

    The above post is reprinted from materials provided by NOAA Fisheries West Coast Region. Note: Materials may be edited for content and length.


    Journal Reference:

    1. Michael G. Jacox, Elliott L. Hazen, Katherine D. Zaba, Daniel L. Rudnick, Christopher A. Edwards, Andrew M. Moore, Steven J. Bograd. Impacts of the 2015-2016 El Niño on the California Current System: Early assessment and comparison to past events. Geophysical Research Letters, 2016; DOI: 10.1002/2016GL069716
  8. Warmest June on record for contiguous U.S.

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    Warmest June on record for contiguous U.S.

    U.S. experienced at least 8 billion-dollar disasters so far this year 
    Contact

    John Leslie, john.leslie@noaa.gov, 301-713-0214

    Brady Phillips, brady.phillips@noaa.gov, 202-407-1298

    July 7, 2016
    The June temperature for the contiguous U.S. was 71.8°F, or 3.3°F above the 20th century average, surpassing the previous record of 71.6°F set in 1933. The year-to-date (January-June) temperature  was 50.8°F, 3.2°F above the 20th century average, making it the third warmest on record.

    The June precipitation total for the contiguous U.S. was 2.46 inches, 0.47 inch below the 20th century average, the 14th driest on record. Record flooding devastated parts of southern West Virginia while wildfires raged across the drought-stricken West. The year-to-date precipitation total was 15.58 inches, 0.27 inch above average, and ranked near the middle value in the 122-year period of record.

    During the first half of 2016, the U.S. experienced eight weather and climate disasters* that have each met or exceeded $1 billion in damages, resulting in the loss of 30 lives and costing more than $13.1 billion in damages.

    This monthly summary from NOAAs National Centers for Environmental Information  is part of the suite of climate services NOAA provides to government, business, academia and the public to support informed decision-making.


    June 2016


    June 2016 Divisional Average Temperature Ranks (Credit: NOAA)


    June 2016 Divisional Average Precipitation Ranks (Credit: NOAA)

    Temperature

    • Above-average temperatures spanned the nation from coast to coast. Seventeen states across the West, Great Plains and parts of the Southeast had June temperatures that were much above average. Above-average temperatures continued for Alaska, which had its ninth warmest June with a temperature 2.4°F above average. Arizona and Utah were each record warm with temperatures 5.9°F and 7.0°F above average, respectively.
      • The warm and dry conditions across the West created ideal wildfire conditions with several large fires impacting the region. The Erskine fire charred nearly 48,000 acres in Southern California, destroying more than 280 homes and killing two people.

    Precipitation

    • Below-average precipitation was widespread across the Northern and Central Plains, Midwest and Northeast. Five states – Massachusetts, Nebraska, South Dakota, Rhode Island and Wyoming – had June precipitation totals that were much below average.
    • Above-average precipitation was observed across parts of the Southwest, Southern Plains, Midwest and Mid-Atlantic. In Arizona, rainfall associated with the seasonal monsoon caused flooding across parts of the state.
      • Despite West Virginia having a June statewide precipitation total that only ranked as the 14th wettest, on June 23-24 a series of thunderstorms passed over southern parts of the state dropping upwards of 10 inches of rain on already saturated soils. The rapid rainfall rates across the mountainous terrain caused massive runoff and record flooding in the valley floors. Over 1,500 homes were destroyed and at least 23 fatalities were blamed on the flooding, including 15 in the small town of Rainelle.
    • According to the June 28 U.S. Drought Monitor report, 16.2 percent of the contiguous U.S. was in drought, up about 3.5 percent compared to the end of May. Drought conditions worsened across parts of the Southeast, Northwest and Northeast with drought developing in the Northeast and parts of the Upper Midwest and Northern Plains. Drought conditions remain entrenched across much of California.

    Year-to-date (January-June) 2016

    Year-to-date (Jan.-June) 2016 Divisional Average Temperature Ranks (Credit: NOAA)

    Year-to-date (Jan.-June) 2016 Divisional Average Precipitation Ranks (Credit: NOAA)

    Temperature

    • Above-average temperatures spanned the nation for the first six months of 2016, with every state being warmer than average. Overall, the contiguous U.S. was the third warmest on record. Thirty-three states across the West, Great Plains, Midwest and Northeast were much warmer than average, while parts of the Southern Plains and Southeast observed above-average temperatures.  No state in the contiguous U.S. was record warm.
    • Alaska was record warm for the year-to-date with a statewide temperature of 30.4°F, 9.0°F above the 1925-2000 average. This bested the previous record of 27.9°F set in 1981. Record warmth spanned the state. The year-to-date temperature in Anchorage was 40.8°F, 6.8°F above the 1981-2010 normal and 2.2°F higher than the previous record set in 1981.

    Precipitation

    • Year-to-date precipitation totals across the contiguous U.S. were mixed. Above-average precipitation was observed for parts of the Northwest, Great Plains, Midwest, and Southwest. Below-average precipitation fell in a string of states from the Mid-Mississippi Valley to the Southeast and across the Northeast. No state was record dry or wet for the six-month period, but Connecticut had its ninth driest year-to-date.

    Extremes

    • During the first half of 2016, there were eight weather and climate disasters* with losses exceeding $1 billion each across the U.S.: two flooding and six severe storm events.  A high number of these events impacted Texas throughout the spring – most notably – several intense hail storms overly densely populated cities and the April 17 Houston flood. The first six months of 2016 were well above the 1980-2016 average of 2.8 events, and ranked as the second most behind only 2011 when 10 such events occurred during January-June. The most billion-dollar events in a single year was 16 in 2011.  Since 1980 the U.S. has sustained 196 weather and climate disasters where overall damages/costs reached or exceeded $1 billion. Combined, the total cost exceeds $1.1 trillion.
    • The U.S. Climate Extremes Index (USCEI) for the year-to-date was 80 percent above average and the fifth highest value on record. On the national scale, extremes in warm maximum and minimum temperatures, the spatial extent of wetness and one-day precipitation totals were much above average. The USCEI is an index that tracks extremes (falling in the upper or lower 10 percent of the record) in land-falling tropical cyclones, temperature, precipitation and drought across the contiguous U.S.

    * Note: The year-to-date billion dollar disaster assessment does not include the devastating late-June flooding event in West Virginia, as those losses are still being assessed.

    The complete U.S. climate report for June 2016 will be available on Tuesday, July 12 at: https://www.ncdc.noaa.gov/sotc/national/201606.

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  9. California droughts caused mainly by changes in wind, not moisture

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    California droughts caused mainly by changes in wind, not moisture

    Posted: 05 Jul 2016 07:26 AM PDT

    Droughts in California are mainly controlled by wind, not by the amount of evaporated moisture in the air, new research has found. The research increases the understanding of how the water cycle is related to extreme events and could eventually help in predicting droughts and floods. … “Ocean evaporation has little direct influence on California precipitation because of its relatively weak variability,” Wei said.
    Instead, the researchers found that disturbances in atmospheric circulation, the large-scale movement of air, have the most effect on drought because they can affect factors that will cause it to rain more or less.

    ….Most of California has been in a severe drought since 2011, although a strong El Niño in the winter of 2015 helped diminish the drought. The current drought is caused by a high-pressure system that disturbs the atmospheric circulation. The development of the high-pressure system is related to a sea surface temperature pattern in the Pacific Ocean, according to research cited by the study.

    Although this is a very rare event, the probability of this kind of high-pressure system is likely increasing with global warming,” the authors said. Yang said that the research could aid in the prediction of droughts and floods by improving scientific understanding of the intricate factors that influence rainfall the most. “The topic is extremely timely as current and future climate change would mean more changes in extreme events such as droughts and floods,” Yang said. “Understanding this asymmetric contribution of ocean evaporation to drought and flooding in California will ultimately help us make better predictions.”

    Jiangfeng Wei, Qinjian Jin, Zong-Liang Yang, Paul A. Dirmeyer. Role of ocean evaporation in California droughts and floods. Geophysical Research Letters, 2016; DOI: 10.1002/2016GL069386


    This is California as viewed from the International Space Station.

    Credit: NASA, Stuart Rankin