Near-future heat and precipitation extremes predicted

Long-term and average changes are in the focus of the discussion on climate change: globally, as the different scientific climate models all predict, it will be warmer on Earth at the end of the century. For decision-makers and people affected by climate change, however, information on the frequency and intensity of extreme events such as heat and cold extremes, heavy rainfall or dry spells are at least as important as indications of average values. Moreover, for them projections about the next ten, twenty, thirty or forty years are usually more relevant than the long-term view to the end of the century. The problem: for the short and medium term, the models yield extremely different results.

Does that mean that the models are not working? No, says Erich Fischer, a senior scientist at the Institute for Atmospheric and Climate Science at ETH Zurich, who has been investigating the causes of the major discrepancies in the short and medium-term projections. In a study just published in the journal "Nature Climate Change," he concludes that they are mostly caused by natural, chaotic and thus unpredictable fluctuations in the climate system. There is certainly potential for improving climate models, Fischer says. "However, even if we had a perfect model for the medium-term, there would still be uncertainties."

Butterfly effect simulated

The researchers obtained their results from a simulation of the well-known butterfly effect, which states that slightly different starting conditions can vastly influence a development in the longer term ("Does the flap of a butterfly's wings in Brazil set off a tornado in Texas?"): the scientists calculated the future climate twenty-one times using one of the leading climate models, deliberately changing the temperatures on Day 1 of the calculation ever so slightly for every point on Earth -- by a maximum of one hundred billionths of a degree Celsius.

This revealed that the differences in the maximum and minimum annual temperatures and the intensive precipitation between 2016 and 2035 were almost as great in the realisations of this one model as the known differences between the various models. From these results the researchers concluded that the majority of the differences are due to the starting conditions and thus chaos, not the uncertainties of the models.

What can be predicted and what can't

"Our study reveals that we have to live with uncertainties in local, medium-term projections," says Fischer. A Swiss farmer, for instance, cannot expect any accurate predictions on the changes in climate extremes on the Swiss Central Plateau in the next thirty to forty years, even if it is clear that the heat extremes and periods of heavy rainfall in the long-term trend will be more intense by the end of the century.

However, this does not mean to say that no scientific projections about the coming decades are possible. The ETH-Zurich scientists have found ways to make such projections -- by considering large regions or the entire world. This enabled them to demonstrate that the intensity of heat extremes and periods of heavy rainfall will not increase equally everywhere on Earth: while heat extremes will become significantly more intense on two thirds of the land surface within three decades, there will be no significant changes in a third of the area. And as far as heavy rainfall is concerned, it will increase by ten per cent in a quarter of the area and less than ten per cent in the remaining three quarters.

Risks predictable

The ETH-Zurich researchers make similar projections for large individual regions such as Europe, the USA, China or Australia. In all these regions, the climate models predict an increase in the intensity of heat waves in the next thirty years and heavy rainfall in the next fifty years. For institutions with a global focus, such as reinsurance companies or food multinationals, such predictions are extremely useful, even if it is unclear where exactly the extreme events will occur. "The different models agree that changes in extreme weather events will occur and how strong they will be, but not where they will be the strongest. This is largely determined by chaos," says Fischer. In physics, it is common for a single condition not to be predictable but probably the average. Fischer compares it with road traffic: if speed limits are increased, we can predict that there will more traffic accidents. Where exactly the next accident will take place, however, we cannot tell.

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The above story is based on materials provided by ETH Zurich. Note: Materials may be edited for content and length.

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Significant harmful algal bloom predicted in western Lake Erie this summer

July 2, 2013

Satellite image of 2011 bloom (the most severe in decades).

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(Credit: MERIS/NASA; processed by NOAA/NOS/NCCOS )

NOAA and its research partners predict that the 2013 western Lake Erie harmful algal bloom (HAB) season will have a significant bloom of cyanobacteria, a toxic blue-green algae, this summer. The predicted bloom is expected to be larger than last year, but considerably less than the record-setting 2011 bloom. Bloom impacts will vary across the lake’s western basin. This marks the second time NOAA has issued an annual outlook for western Lake Erie.

“This annual forecast and NOAA’s weekly bulletins provide the most advanced ecological information possible to Great Lakes businesses and resource managers so they can save time and money on the things they do that drive recreational activities and the economy,” said Holly Bamford, Ph.D., NOAA’s assistant administrator for the National Ocean Service.

Satellite image of 2012 bloom (1/6 the size of 2011).

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(Credit: MERIS/NASA; processed by NOAA/NOS/NCCOS)

Harmful algae blooms were common on western Lake Erie in the 1960s and 1970s. After a lapse of nearly 20 years, they have been steadily increasing over the past decade. As an early warning system, NOAA has issued weekly HABS bulletins for western Lake Erie since 2008 through the National Centers for Coastal Ocean Science (NCCOS). The weekly bulletins will continue in 2013.

“This information is critical for tourists, coastal businesses, water treatment plant operators, state and regional natural resource managers and scientists throughout Ohio, the region, and the country,” said Jeff Reutter, Ph.D., director of  Ohio State University’s Sea Grant program and Stone Laboratory. “In Ohio, as part of our Phosphorus Task Force II, we have used information from the NOAA model to help us target reductions in the amount of phosphorus going into the lake that would eliminate, or greatly reduce, the HABs.”

“The timing, size and location of blooms heavily impact our charter businesses,” said Captain Rick Unger, owner of Chief’s Charters and president of the Lake Erie Charter Boat Association. “I use the weekly bulletins to plan my trip routes and fuel costs, but more importantly they help me get our visitors out of their hotel rooms and onto the water.”

The 2013 seasonal forecast, made possible using NOAA models developed by NCCOS scientists, uses an 11-year data set of nutrients flowing into Lake Erie, collected by the Heidelberg University’s National Center for Water Quality Research, and analysis of satellite data from the European Space Agency’s Envisat. In addition to the satellite monitoring of the lake, NOAA’s Great Lakes Environmental Research  Laboratory, Ohio State University’s Sea Grant Program and Stone Laboratory, Heidelberg University, the University of Toledo, and Ohio EPA will be collecting key measurements from the lake as the summer progresses. Those results will provide valuable information to regional managers and assist NCCOS scientists in further refining the accuracy of this forecast’s models.

“Issuing and evaluating this seasonal forecast allows us to develop ways to help resource managers plan for conditions that will occur later in the summer,” said Richard Stumpf, Ph.D., NOAA’s ecological forecasting applied research lead at NCCOS. “Through partnerships with Heidelberg University and Ohio Sea Grant, we bring live tools to regional managers currently facing HAB challenges, but we are also constantly re-calibrating and evolving our forecasting products to meet changing HAB conditions.”

The NOAA forecast models and analyses draw on several sources, including nutrient data from Heidelberg University’s National Center for Water Quality Research and satellite data from
MERIS and NASA’s Moderate Resolution Imaging Spectro-radiometer. Funding to support the
program was provided through NCCOS, NOAA’s Center of Excellence for Great Lakes and Human Health, and NASA’s Applied Science Health and Air Quality Program.

The Lake Erie forecast is part of a NOAA ecological forecasting initiative that aims to deliver accurate, relevant, timely, and reliable ecological forecasts directly to coastal resource managers and the public as part of its stewardship and scientific mandates for coastal, marine and Great Lakes resources. Additionally, NOAA currently provides, or is developing, HABs and hypoxia forecasts for the Gulf of Maine, Chesapeake Bay, the Gulf of Mexico and the Pacific Northwest.

The National Centers for Coastal Ocean Science is the coastal science office for NOAA’s National Ocean Service. Visit our website or follow our blog to read more about NCCOS research.

NOAA’s mission is to understand and predict changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Join us on Facebook, Twitter and our other social media channels.

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Scientists find large Gulf dead zone, but smaller than predicted

July 29, 2013

Map showing the hypoxia area on the Louisiana Gulf of Mexico shelf in 2013.

Download here (Credit: LUMCON (Rabalais))

NOAA-supported scientists found a large Gulf of Mexico oxygen-free or hypoxic “dead” zone, but not as large as had been predicted. Measuring 5,840 square miles, an area the size of Connecticut, the 2013 Gulf dead zone indicates nutrients from the Mississippi River watershed are continuing to affect the nation’s commercial and recreational marine resources in the Gulf.

“A near-record area was expected because of wet spring conditions in the Mississippi watershed and the resultant high river flows which deliver large amounts of nutrients,” said Nancy Rabalais, Ph.D. executive director of the Louisiana Universities Marine Consortium (LUMCON), who led the July 21-28 survey cruise. “But nature’s wind-mixing events and winds forcing the mass of low oxygen water towards the east resulted in a slightly above average bottom footprint.”

Hypoxia is fueled by nutrient runoff from agricultural and other human activities in the watershed. These nutrients stimulate an overgrowth of algae that sinks, decomposes and consumes most of the oxygen needed to support life. Normally the low or no oxygen area is found closer to the Gulf floor as the decaying algae settle towards the bottom. This year researchers found many areas across the Gulf where oxygen conditions were severely low at the bottom and animals normally found at the seabed were swimming at the surface.

Graph showing historical hypoxia trends.

Download here (Credit: LUMCON (Rabalais))

This is in contrast to 2012, when drought conditions resulted in the fourth smallest dead zones on record, measuring 2,889 square miles, an area slightly larger than Delaware. The largest previous dead zone was in 2002, encompassing 8,481 square miles. The smallest recorded dead zone measured 15 square miles in 1988. The average size of the dead zone over the past five years has been 5,176 square miles, more than twice the 1,900 square mile goal set by the Gulf of Mexico / Mississippi River Watershed Nutrient Task Force in 2001 and reaffirmed in 2008.

On June 18, NOAA-sponsored forecast models developed by Donald Scavia, Ph.D., University of Michigan, and R. Eugene Turner, Ph.D., Louisiana State University,  predicted the Gulf hypoxic zone would range in size from 7,286 to 8,561 square miles.

“NOAA’s investment in the Gulf of Mexico continues to yield results that confirm the complex dynamics of hypoxia and provide managers and the public with accurate scientific information for managing and restoring the nation's valuable coastal resources,” said Robert Magnien, Ph.D., director of NOAA’s Center for Sponsored Coastal Ocean Research. “For those who depend upon and enjoy the abundant natural resources of the Gulf of Mexico, it is imperative that we intensify our efforts to reduce nutrient pollution before the ecosystem degrades any further.”

This annual measurement provides federal and state agencies working on the 2008 Gulf task force implementation actions with the real consequences of inadequate nutrient pollution management. The task force’s actions are set for review this summer.

The hypoxic zone off the coast of Louisiana and Texas forms each summer threatening the ecosystem supporting valuable commercial and recreational Gulf fisheries that in 2011 had a commercial dockside value of $818 million and an estimated 23 million recreational fishing trips. The Gulf task force, in its 2008 report, states that "hypoxia has negative impacts on marine resources." It further states that research on living resources in the Gulf show long term ecological changes in species diversity and a large scale, often rapid change, in the ecosystem's food-web that is both "difficult and impossible to reverse." Additionally, there are numerous annual areas of the Gulf where large scale fish kills occur as a result of hypoxia.

Two surveys conducted in June and early July, one of which was led by a NOAA-supported Texas A&M University team, suggested a large hypoxic zone was forming in the Gulf, though the LUMCON July measurement will be the official one as required of NOAA by the Task Force. NOAA’s National Marine Fisheries Service, in conducting its Southeast Monitoring and Assessment Program groundfish surveys, also found large expanses of hypoxia in June-early July. Texas A&M will be conducting a follow-up cruise in mid-August to provide its final seasonal update.

Visit the Gulf Hypoxia web site for additional graphics and information concerning this summer’s LUMCON research cruise, and previous cruises.

NOAA’s National Ocean Service has been funding monitoring and research for the dead zone in the Gulf of Mexico since 1985 and currently oversees the NGOMEX program, the hypoxia research effort for the northern Gulf which is authorized by the Harmful Algal Bloom and Hypoxia Research and Control Act.

The National Centers for Coastal Ocean Science is the coastal science office for NOAA’s National Ocean Service.

NOAA’s mission is to understand and predict changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Join us on Facebook, Twitter and our other social media channels.

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