The research team used tree rings dating to 1506 to track past wildfire activity in the forests of Patagonia tied to the Southern Annular Mode, or SAM, a climate oscillation that creates low atmospheric pressure in the Antarctic that is tied to warmer and drier conditions in southern South America.
This 2010 photo shows the aftermath of a wildfire outside the town of Futaleufu in southern Chile. A new study by CU-Boulder researchers indicates that wildfires may intensify in southern South America in the coming decades. Credit: Andres Holz
The tree rings showed that when SAM was in its positive phase, there were widespread fires in both dry woodlands and rainforests in Patagonia, a region that straddles Argentina and Chile, said CU-Boulder Research Associate Andres Holz, lead study author.
"Our study shows for about the past 250 years, the Southern Annular Mode has been the main driver in creating droughts and fires in two very different ecosystems in southern South America," said Holz. "Climate models suggest an increase in SAM beginning in the 1960s due to greenhouse gas increases and Antarctic ozone depletion probably will cause this region to be drought-prone and fire-prone for at least the next 100 years."
A paper on the subject by Holz and CU-Boulder geography Professor Thomas Veblen was published in Geophysical Research Letters.
Holz and Veblen compared past wildfire records for two ecologically distinct regions in Patagonia -- the relatively dry region of southern Patagonia in Argentina and the temperate rainforest of Patagonia in northern Chile. While the tree ring historical record showed increased fires in both regions correlated with a positive SAM, the trend has been less pronounced in northern Patagonia in the past 50 years, likely because of fire-suppression efforts there, Holz said.
But the decades of fire suppression have caused the northern Patagonian woodlands to become denser and more prone towildfire during hot and dry years, Holz said.
"Even in areas of northern Patagonia where fire suppression previously had been effective, record surface areas of woodlands and forests have burned in recent years of extreme drought," said Veblen. "And since this is in an area of rapid residential growth into wildland-urban interface areas, this climate-driven trend towards increasing fire risk is becoming a major problem for land managers and homeowners."
The two CU-Boulder researchers studied reconstructions of tree rings going back more than 500 years from 432 trees at 42 sample sites in northern Argentina and southern Chile -- the largest available data set of annual, readable tree ring records in the Southern Hemisphere. The tree rings, which indicate climate cycles and reveal the scars of old fires, showed that wildfires generally increased in both regions when SAM was in its strong, positive phase.
Although the Antarctic ozone hole stopped growing in about 2000 as a result of a ban on ozone-depleting gases and now appears to be slowly repairing itself, a 2011 paper by researchers at the National Center for Atmospheric Research in Boulder indicates ozone recovery and greenhouse gas influences essentially will cancel each other out, preventing SAM from returning to its pre-1960s levels.
"Before the Industrial Revolution, SAM intensified naturally at times to create drought situations in Patagonia," Holz said. "But in the last 80 years or so, the natural variation has been overwhelmed by a bias toward a positive SAM phase because of ozone-depleting chemicals and greenhouse gases we have put in the atmosphere."
The research effort was supported by the National Geographic Society, the National Science Foundation, the CU Beverly Sears Small Grants Program and the Council on Research and CreativeResearch of the CU Graduate School.
"As warming and drying trends continue, it is likely that wildfire activity will increase even in woodland areas where fire suppression has previously been effective," Holz and Veblen wrote in Geophysical Research Letters.Contact:
Andres Holz | EurekAlert!
Research sheds new light on forces that threaten sensitive coastlines
24.04.2017 | Indiana University
NASA sees the end of ex-Tropical Cyclone 02W
21.04.2017 | NASA/Goddard Space Flight Center
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Life Sciences
24.04.2017 | Earth Sciences
24.04.2017 | Machine Engineering