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Tag Archive: temperature

  1. Adapting Forests to Climate Change- new UC guide

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    UC helps forest owners adapt to climate change

    By Jeannette E. Warnert April 5, 2017 University of California Division of Agriculture and Natural Resources Blog

    The new publication, Adapting Forests to Climate Change, can be downloaded free from the UC ANR Catalog. It is the 25th in the Forest Stewardship series, developed to help forest landowners in California learn how to manage their land. It was written by Adrienne Marshall, a doctoral student at the University of Idaho; Susie Kocher, UC Cooperative Extension forestry and natural resources advisor; Amber Kerr, postdoctoral scholar with the UC John Muir Institute of the Environment; and Peter Stine, U.S. Forest Service.

    The document provides specific recommendations for care of three common types of forest in California: mixed conifer, oak woodland and coastal redwood forests… see page 12 for specific management recommendations.

  2. Can Meadows Rescue the Planet from CO2?

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    An unusual research project is determining whether restoring California’s meadows can reduce atmospheric carbon dioxide

    By Jane Braxton Little on May 11, 2017 Scientific American

    …Scientists and land managers are heading into the mountains to measure the greenhouse gas activity at 16 hand-picked meadows—some recently restored, others degraded from a century of grazing and logging.

    The four-year study is part of California’s pioneering effort to reduce carbon emissions. The project is designed to determine whether restored meadows hold more carbon than those that have been degraded. The outcome could prove pivotal for California and the planet. Worldwide, soils store three times more carbon than vegetation and the atmosphere combined. If the research shows restored meadows improve carbon storage, it could stimulate meadow restoration around the world….

    A December study published in Nature… found rising temperatures are stimulating a net loss of soil carbon to the atmosphere. Warmer soils accelerate the flux, sending more carbon into the ground and more carbon dioxide back out into the atmosphere. As warmth increases microbial activity, decomposition and respiration outpace photosynthesis, particularly in the world’s colder places. …” The changes could drive a carbon–climate feedback loop that could accelerate climate change.”…

    …The research covers meadows from the base of Lassen Peak in the north to areas nearer to Los Angeles. The meadows range in elevation from 3,045 to nearly 8,700 feet; they include granitic, volcanic and metamorphic soils. A critical facet of the partnership is developing precise procedures for when and how to measure and analyze meadow greenhouse gases.

    ……a limited study conducted by the University of Nevada, Reno (U.N.R.). Scientists collected soil samples at seven meadows in the northern Sierra restored between 2001 and 2016, pairing restored sites with similar, adjacent unrestored sites….found an average of 20 percent more soil carbon in restored meadows, with one site recording an increase of over 80 percent. Meadows immediately begin storing carbon following restoration, with significant increases over 15 years, says Cody Reed, a research assistant working with Ben Sullivan, a U.N.R. soil scientist and assistant professor. The investigation seems to show restored meadows add soil carbon and also slow losses to the atmosphere.

    …[In another study] they found surprised them: Carbon dioxide emissions were unaffected by soil moisture content, and methane sequestration was prevalent, particularly on the dry side of wet meadow. The 2014 study also found plant species richness and soil carbon concentration appeared more important than soil moisture in explaining carbon fluxes.

     

  3. Warmer temperatures cause decline in runoff ratio and water supply

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    Finding could improve water supply forecasting

    May 11, 2017 National Center for Atmospheric Research/University Corporation for Atmospheric Research  (from ScienceDaily)

    …The study paints a detailed picture of how temperature has affected the runoff ratio — the amount of snow and rain that actually makes it into the river — over time, and the findings could help improve water supply forecasts for the Rio Grande, which is a source of water for an estimated 5 million people. The study results also suggest that runoff ratios in the Upper Rio Grande and other neighboring snow-fed watersheds, such as the Colorado River Basin, could decline further as the climate continues to warm.

    “The most important variable for predicting streamflow is how much it has rained or snowed,” said NCAR scientist Flavio Lehner, lead author of the study. “But when we looked back hundreds of years, we found that temperature has also had an important influence — which is not currently factored into water supply forecasts. We believe that incorporating temperature in future forecasts will increase their accuracy, not only in general but also in the face of climate change….

    Current operational streamflow forecasts depend on estimates of the amount of snow and rain that have fallen in the basin, and they assume that a particular amount of precipitation and snowpack will always yield a particular amount of streamflow.

    In recent years, those forecasts have tended to over-predict how much water will be available, leading to over-allocation of the river…”The effect of temperature on runoff ratio is relatively small compared to precipitation,” Lehner said. “But because its greatest impact is when conditions are dry, a warmer year can make an already bad situation much worse.”…

    Flavio Lehner, Eugene R. Wahl, Andrew W. Wood, Douglas B. Blatchford, Dagmar Llewellyn. Assessing recent declines in Upper Rio Grande River runoff efficiency from a paleoclimate perspective. Geophysical Research Letters, 2017; DOI: 10.1002/2017GL073253

  4. Global climate risk reduced significantly with aggressive emissions reductions

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    • takes less than 20 years for risk of extreme heat to halve from start of aggressive emissions reductions
    • climate payback with major GHG reductions comes faster than previously thought

    Posted: 03 Apr 2017 09:33 AM PDT  ScienceDaily article here

    Climate scientists have shown the early mitigation needed to limit eventual warming below potentially dangerous levels has a climate ‘payback’ much earlier than previously thought.

    Ciavarella and the team discovered that it takes less than 20 years in many regions for the risk of extreme seasonal temperatures (one-in-ten-year extreme heat events) to halve following the start of aggressive emissions reductions.

    Andrew Ciavarella added: “We show that the global exposure to climate risk is reduced markedly and rapidly with substantial reductions of greenhouse gas emissions. It had been thought previously that most of the benefits of mitigation would have been hidden by natural climate variability until later in the century.”…

    Andrew Ciavarella, Peter Stott, Jason Lowe. Early benefits of mitigation in risk of regional climate extremes. Nature Climate Change, 2017; DOI: 10.1038/nclimate3259

  5. Large Sections of Australia’s Great Reef Are Dead Due to Ocean Warming, Scientists Find

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    Washington Post March 19 2017  See full article here

    THE MEASURED warming of the planet is not hypothetical. Nor are its effects, which are happening now, not decades from now. An ecological catastrophe is unfolding off Australia’s coast: Humans are killing the Great Barrier Reef, one of the world’s greatest natural wonders, and there’s nothing Australians on their own can do about it. We are all responsible.

    An ocean water temperature spike last year caused a massive “bleaching” event, in which colorful corals turned an antiseptic, sickly white. Scientists believe that the reef will never be the same.

    The chances of the northern Great Barrier Reef returning to its pre-bleaching assemblage structure are slim given the scale of damage that occurred in 2016 and the likelihood of a fourth bleaching event occurring within the next decade or two as global temperatures continue to rise,” a major new study in the journal Nature reported last week….

    ….Alarmingly, but perhaps not surprisingly, the Australian government reports that sections of the reef are getting slammed again this year….

    There is little doubt that temperature is the culprit. Reefs far away from human runoff and other local risks are suffering. Corals in pristine water bleached just like those in dirty water. The Nature study quantified a relationship between exposure to warm water and the severity of observed bleaching.

    “Immediate global action to curb future warming is essential to secure a future for coral reefs,” the study warned. “Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016.”…

  6. Making cows more environmentally friendly

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    Posted: 29 Mar 2017 09:26 AM PDT ScienceDaily summary here

    An important discovery surrounding plants used to feed livestock has been released by scientists. They report that plants growing in warmer conditions are tougher and have lower nutritional value to grazing livestock, potentially inhibiting milk and meat yields and raising the amount of methane released by the animals. Higher amounts of methane are produced when plants are tougher to digest — an effect of a warmer environment. Methane is a potent greenhouse gas, around 25 times better at trapping heat than carbon dioxide. More than 95% of the methane produced by cows comes from their breath through eructation (belching) as they “chew the cud.”

    “Our research has shown that cultivating more nutritious plants may help us to combat the challenges of warmer temperatures. We are undertaking work at Kew to identify the native forage plants that are associated with high meat and milk production and less methane, attempting to increase their presence on the grazing landscape. We are also developing our models to identify regions where livestock are going to be exposed to reductions in forage quality with greater precision. It is going to be important to put plans in place to help those countries exposed to the most severe challenges from climate change to adapt to a changing world” said Dr Mark Lee.

    Mark A. Lee, Aaron P. Davis, Mizeck G. G. Chagunda, Pete Manning. Forage quality declines with rising temperatures, with implications for livestock production and methane emissions. Biogeosciences, 2017; 14 (6): 1403 DOI: 10.5194/bg-14-1403-2017

  7. Climate study: More intense and frequent severe rainstorms likely

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    Climate study: More intense and frequent severe rainstorms likely

    Posted: 07 Mar 2017 07:03 AM PST

    A climate scientist confirms that more intense and more frequent severe rainstorms will likely continue as temperatures rise due to global warming, despite some observations that seem to suggest otherwise…

    Guiling Wang, Dagang Wang, Kevin E. Trenberth, Amir Erfanian, Miao Yu, Michael G. Bosilovich, Dana T. Parr. The peak structure and future changes of the relationships between extreme precipitation and temperature. Nature Climate Change, 2017; DOI: 10.1038/nclimate3239

  8. Long-term eelgrass loss due to joint effects of shade, heat

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    Analysis puts resulting economic losses at $1-2 billion in Chesapeake Bay alone

    February 14 2017  Science Daily see full article here

    A new study links a long-term decline in Chesapeake Bay’s eelgrass beds to both deteriorating water quality and rising summertime temperatures. It also shows that loss of the habitat and other benefits that eelgrass provides comes at a staggering ecological and economic cost…….”Declining water clarity has gradually reduced eelgrass cover during the past two decades, primarily in deeper beds where lack of light already limits growth. In shallow beds, it’s more that heat waves are stressing the plants, leading to the sharp drops we’ve seen in recent summers.”

    “Not only have we lost a huge ecological resource, there have been real economic and recreational consequences….Blue crab fisheries, for example, have probably lost a year or more of catch based on the amount of eelgrass we’ve already lost. For silver perch, it’s 10-20 years. In all, we estimate the potential economic cost to citizens at $1-2 billion.”…

    …mean summertime water temperature in the lower Chesapeake Bay has already increased by more than 2 degrees Fahrenheit since 1984 — from 76.8° to 79.5°F — and that the frequency of extreme warm spells with water temperatures exceeding 82° has doubled in the last decade….As global warming continues to raise the area’s water temperatures — a conservative estimate is a further 3.5° F increase by 2040 — the team predicts a further 38% decline in eelgrass cover. And if water clarity follows its current downward trajectory during the next 30 years, eelgrass would decline an additional 84%. When both declining clarity and warming are considered, say the researchers, the predicted increases in temperature and turbidity would result in a loss of 95% of Bay eelgrass — a near total eradication

    …”Our analysis suggests that eelgrass could still persist in the face of moderate increases in temperature, if the water remains clear enough” adds Lefcheck. “But that will only happen if managers adopt an integrated perspective, and continue with their efforts to curb inputs into the Bay.

    Jonathan S. Lefcheck, David J. Wilcox, Rebecca R. Murphy, Scott R. Marion, Robert J. Orth. Multiple stressors threaten the imperiled coastal foundation species eelgrass (Zostera marina) in Chesapeake Bay, USA. Global Change Biology, 2017; DOI: 10.1111/gcb.13623

  9. Temperature drives biodiversity

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    Posted: 22 Dec 2016 06:58 AM PST ScienceDaily see full article here

    Why is the diversity of animals and plants so unevenly distributed on our planet? An international research team of researchers has provided new data on this core issue of ecology. They found biodiversity to be driven by temperature….

    …The study revealed that biodiversity in communities is mainly determined by temperature. The warmer it is, the greater the diversity. “The more groups of animals and plants you investigate in parallel, the greater the significance of temperature for explaining biodiversity, whereas the importance of all other variables decreases accordingly.”

    The scientists believe that this is strong evidence supporting the assumption that temperature is actually more decisive for distribution patterns of overall biodiversity than productivity or size of habitats.

    Marcell K. Peters et al. Predictors of elevational biodiversity gradients change from single taxa to the multi-taxa community level. Nature Communications, 2016; 7: 13736 DOI: 10.1038/ncomms13736

  10. Global Warming Alters Arctic Food Chain, Scientists Say, With Unforeseeable Result

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    The Arctic Ocean may seem remote and forbidding, but to birds, whales and other animals, it’s a top-notch dining destination. “It’s a great place to get food in the summertime, so animals are flying or swimming thousands of miles to get there,” said Kevin R. Arrigo, a biological oceanographer at Stanford University.

    But the menu is changing. Confirming earlier research, scientists reported Wednesday that global warming is altering the ecology of the Arctic Ocean on a huge scale. The annual production of algae, the base of the food web, increased an estimated 47 percent between 1997 and 2015, and the ocean is greening up much earlier each year.

    These changes are likely to have a profound impact for animals further up the food chain, such as birds, seals, polar bears and whales. But scientists still don’t know enough about the biology of the Arctic Ocean to predict what the ecosystem will look like in decades to come.

    While global warming has affected the whole planet in recent decades, nowhere has been hit harder than the Arctic. This month, temperatures in the high Arctic have been as much as 36 degrees above average, according to records kept by the Danish Meteorological Institute…