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Droughts are Pushing Trees to the Limit

By Guest PostSeptember 8, 2012Environmentaerial surveys, atmospheric sponge, borderland, carbon dioxide, catastrophic disruption, climate change, deficit, drought, ecological disturbance, elevation, embolism, forest service, four corners, greenhouse experiment, growing season, high plains, index, jeremy weiss, jonathan overpeck, julio betancourt, leaf water, Mexico, moisture, mountainous terrain, photosynthesis, plant growth, precipitation, regional warming, southwest, stomates, temperatures rise, university of arizona, US, vapor pressure, vicious circle, weather data, wildfires

Droughts in the Southwest made more severe by warming temperatures are putting plants in stressful growing conditions, a new study has found, identifying an increasingly water-thirsty atmosphere as a key force that sucks moisture from plants, leading to potentially higher stress – especially in mid and low elevations.

As temperatures rise and droughts become more severe in the Southwest, trees are increasingly up against extremely stressful growing conditions, especially in low to middle elevations, University of Arizona researchers report in a study soon to be published in the Journal of Geophysical Research Biogeosciences.

Lead author Jeremy Weiss, a senior research specialist in the UA department of geosciences, said: “We know the climate in the Southwest is getting warmer, but we wanted to investigate how the higher temperatures might interact with the highly variable precipitation typical of the region.” (more…)

UA Scientists Find Evidence of Roman Period Megadrought

By Guest PostNovember 6, 2011Environment, Scienceannual growth rings of trees, bristlecone pine tree, chronology, climate, cody routson, colorado river, connie woodhouse, core, dendrochronology, extreme drought conditions, geoscientists, jonathan overpeck, la niña, medieval period, multi decade drought period, primary drainage, rio grande, rocky landscapes of alpine or near alpine mountain slopes, san juan bristlecone pines, san juan drainage, san juan rivers, second century a d, shelley littin, south central colorado, southern san juan mountains, southwestern aridity, southwestern u.s, tree bark, tropical pacific ocean, university of arizona

*A new study at the UA’s Laboratory of Tree-Ring Research has revealed a previously unknown multi-decade drought period in the second century A.D. The findings give evidence that extended periods of aridity have occurred at intervals throughout our past.*

Almost nine hundred years ago, in the mid-12^th century, the southwestern U.S. was in the middle of a multi-decade megadrought. It was the most recent extended period of severe drought known for this region. But it was not the first.

The second century A.D. saw an extended dry period of more than 100 years characterized by a multi-decade drought lasting nearly 50 years, says a new study from scientists at the University of Arizona. (more…)

Rising Oceans – Too Late to Turn the Tide?

By Guest PostJuly 16, 2011Environmentantarctic ice sheets, anthropogenic reasons, atmosphere, atmosphere ocean interactions, bahamas, barbados, bette otto bliesner, cause and effect relationships, climate, climate models, computer simulations, current global warming, earth, global distribution of sea surface temperatures, great polar ice sheets, greenhouse gas concentrations, greenhouse gases, greenland, ice caps, jonathan overpeck, last interglacial period, melting ice sheets, mountain glaciers, natural reasons, nicholas mckay, paleoceanic records, paleoclimate, rising sea levels, sea level, thermal expansion of seawater, thermal expansion of warming ocean waters, university of arizona

*Melting ice sheets contributed much more to rising sea levels than thermal expansion of warming ocean waters during the Last Interglacial Period, a UA-led team of researchers has found. The results further suggest that ocean levels continue to rise long after warming of the atmosphere levels off.*

Thermal expansion of seawater contributed only slightly to rising sea levels compared to melting ice sheets during the Last Interglacial Period, a University of Arizona-led team of researchers has found.

The study combined paleoclimate records with computer simulations of atmosphere-ocean interactions and the team’s co-authored paper is accepted for publication in Geophysical Research Letters. (more…)

Rising Seas Will Affect Major U.S. Coastal Cities by 2100

By Guest PostFebruary 19, 2011Environmentglobal average temperature, global warming, jonathan overpeck, national elevation dataset, new orleans, rising sea affect, rising sea levels, southern atlantic coasts, us coastal cities, virginia beach

*The Gulf and southern Atlantic coasts will be particularly hard hit, research predicts. Miami, New Orleans, Tampa, Fla., and Virginia Beach, Va. could lose more than 10 percent of their land area by 2100*

Rising sea levels could threaten an average of 9 percent of the land within 180 U.S. coastal cities by 2100, according to new research led by University of Arizona scientists. (more…)

Tag Archives: jonathan overpeck

Droughts are Pushing Trees to the Limit

UA Scientists Find Evidence of Roman Period Megadrought

Rising Oceans – Too Late to Turn the Tide?

Rising Seas Will Affect Major U.S. Coastal Cities by 2100