States like Washington, Oregon, California, Colorado, New Mexico, Arizona and South Dakota all had an increased prevalence of wildfires in recent centuries when a phenomenon known as the Atlantic Multi-Decadal Oscillation -- similar but longer in duration than the better known El Nino-Southern Oscillation -- periodically shifted from a cool to a warm mode that lasted roughly 60 years each time, said the study authors.
Warmer waters in the North Atlantic correspond with episodes of drought and subsequent fires in the West as shown by fire scars in annual tree rings studied by the researchers, said Thomas Kitzberger of the University of Comahue, who led the study with researchers from CU-Boulder, the University of Arizona, the U.S. Forest Service and Rocky Mountain Tree-Ring Research Inc., a private lab in Fort Collins, Colo.
Kitzberger, who received his doctorate from CU-Boulder in 1994 under co-author and CU-Boulder geography Professor Thomas Veblen, said the North Atlantic warming trend, coupled with warming temperatures and the earlier onset of spring in the West, poses "an increased hazard for wildfires that may continue for decades." The paper was published the week of Dec. 25 in the Proceedings of the National Academy of Sciences.
While previous tree-ring studies have linked fires in different regions of western North America to drought associated with the warm El Niño phase or cool La Niña phase of the Southern El-Niño Southern Oscillation phenomenon in the Pacific, the new study is the first to correlate the Atlantic Multi-Decadal Oscillation with increased North American fires on such a large scale, said the authors. The team analyzed nearly 34,000 individual fire scar dates from tree rings, primarily ponderosa pine and Douglas fir, at 241 sites -- the largest record of tree rings linked to past wildfires ever assembled.
"This trend of warmer sea-surface temperatures in the North Atlantic appears to be correlated with dry spells we have seen in the West since the late 1990s," said Veblen. "If the trend continues for the next 60 years or so as it has in the past, the degree of fire occurrence in the West could be unprecedented compared to anything in recent memory."
Although the atmospheric mechanisms relating drought in North America to sea-surface temperatures in the North Atlantic are subject to debate among climatologists, there is a strong statistical association of drought and fire in western North America when the Atlantic sea surface warms, said Veblen. The sea-surface temperature of both the Atlantic and Pacific oceans combine to influence the climate of much of the world through a complex web of atmospheric interconnections, he said.
"The key issue is that the Atlantic Multi-Decadal Oscillation persists on time scales of 60 to 80 years, compared to just one year or a few years for El Niño," he said.
Veblen said warmer temperatures in the West since the 1990s have exacerbated outbreaks of spruce and pine beetle populations, which have decimated millions of acres of coniferous forests in the West. "There is good evidence that warming trends like the one we are now seeing is very favorable for the population growth of these beetles."
Fire suppression activities during the 20th century have increased fuels and fire hazard in some forest types, although forest thinning may help reduce the impact of some severe fires by eliminating potential fuel sources, Veblen said. But the effectiveness of such practices pale in comparison to the potential of climatic factors.
"The driving factor influencing wildfires is overwhelmingly climate variation, which is why studies like these are crucial," he said.
"This study underscores the value of building large networks of high-resolution fire history data to better understand how climate may affect fire regimes over large areas of the globe," said Kitzberger. The team used data from the International Multiproxy Paleofire Database that is maintained by the National Oceanic and Atmospheric Administration.
Thomas Veblen | EurekAlert!
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
Value from wastewater
16.08.2017 | Hochschule Landshut
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
21.08.2017 | Materials Sciences
21.08.2017 | Health and Medicine
21.08.2017 | Materials Sciences