Forests may not benefit from rising CO2 levels

Intense aspen and scrub oak color in this aerial view of Eagle County, Colorado.
Aspen and scrub oak forests in western Colorado. @bberwyn photo.

Study says disastrous tipping points could be reached by 2050

Staff Report

Forests of the future may not be able to remove heat-trapping CO2 from the atmosphere as effectively as previously thought, scientists said in a new study that’s based on an extensive analysis of tree ring data from the past.

“We utilized a network of more than two million tree-ring observations spanning North America. Tree-rings provide a record into how trees that grow in different climates respond to changes in temperature and rainfall,” said Brian Enquist, a professor in the UA’s Department of Ecology and Evolutionary Biology and a fellow of the Aspen Center for Environmental Studies in Aspen, Colorado.

The research challenges assumptions about how forests will respond to warmer average temperatures, increased greenhouse gas emissions, and shifting rainfall patterns. It also suggests that the warming climate already is rapidly pushing many forests towards an ecological tipping point, which may be reached as early as 2050, Exposure to unprecedented temperatures hampers tree growth and makes them susceptible to other stress factors. Continue reading “Forests may not benefit from rising CO2 levels”

Will global warming lead to a battle of the birds?

Mountain bluebird.
Mountain bluebird. @bberwyn photo.

Migration changes could affect competition for nesting sites

Staff Report

As global warming speeds up the springtime northward migration of swallows, it could spell trouble for mountain bluebirds.

Both species are cavity nesters; at times they compete for the same habitat. Historically, mountain bluebirds have arrived in the breeding territories earlier than the swallows, giving them a chance to defend their nests. But if the swallows arrive first, the bluebirds may have a harder time finding a safe spot to lay eggs, according to new research published in The Auk: Ornithological Advances.

The scientists from the University of Saskatchewan acknowledged that the outcomes of interspecies battles for nest sites depend on a number of factors, but wanted to study what happens when tree swallows and mountain bluebirds compete for nest sites. So they set up side-by-side pairs of nest boxes in grassland habitat in central British Columbia.

When bluebird and swallow pairs moved in next door to each other, they would either block the entrance to one box and let the two pairs of birds compete for the one that remained, or remove both boxes and replace them with a fresh one.

“I became interested in this topic after watching many competitive interactions over natural tree holes during a long-term study of Northern Flickers in central British Columbia,” said researchers Karen Wiebe. “In early spring when the birds are trying to claim a nest site, these disputes can be intense and really grab your attention. Because bluebirds and swallows readily use nest boxes, I was motivated to try some experiments in a system where I could have more control over the spacing of nests and settlement patterns of the birds.”

Wiebe found that when Tree Swallows were defending their previously owned box or when the two species were competing over a new box, Tree Swallows won 65-70 percent of the time. Bluebirds got a boost when they defended a box they already occupied, however, fending off swallows 77 percent of the time.

Climate change may bring the two species into direct competition more often and reduce bluebirds’ ability to claim and defend nest sites.

“This is a nice set of clever and simple experiments that show that species are not the same when it comes to the importance of being the first one to occupy a nest site,” according to ecologist Hanna Kokko of the University of Zurich, an expert on interspecies competition in birds. “The one that currently tends to arrive first, the bluebird, relies more on this, which could easily cause problems if the arrival order changes on a changing planet.”

Will global warming super-charge hurricanes?

Hurricane Isaac satellite image
Tropical storm Isaac churning in the Gulf of Mexico in 2012. Photo courtesy NOAA.

New study suggests tropical storms will become more intense

Staff Report

Tropical storms may become less frequent as the planet warms up, but those that do form could be increasingly powerful, according to a new study published in the journal Science last week.

How global warming will affect tropical storm formation in the decades ahead has been the subject of intensive research. The new study says that, so far, the warming effects of greenhouse gases on tropical cyclones have been hard to discern because of natural variability and also because air pollution has been masking the impacts. Continue reading “Will global warming super-charge hurricanes?”

Study says old, weathered oil from spills is even more toxic to fish than fresh crude

Scientists still studying Deepwater Horizon spill impacts

Oil from BP's failed Deepwater Horizon drill rig and the Macondo well spread across the ocean in May 2010. PHOTO COURTESY NOAA.
Oil from BP’s failed Deepwater Horizon drill rig and the Macondo well spread across the Gulf of Mexico in May 2010. Photo courtesy NOAA.

Staff Report

It’s been six years since BP’s Deepwater Horizon drilling rig in the Gulf of Mexico failed disastrously, but scientists are still learning about how the oil affected ocean species and ecosystems.

In findings from new study released this week, researchers from the University of California, Riverside and the University of Miami Rosenstiel School of Marine and Atmospheric Science reported that old, weathered oil from the spill is even more toxic than fresh crude oil. Ultraviolet light changes changes the chemistry of the oil, the scientists said, further threatening numerous commercially and ecologically important fishes.

The Deepwater Horizon oil disaster was the worst on U.S. history. More than 3 million barrels of oil spilled into the Gulf, contaminating spawning habitats for many fishes. The oil also killed deep sea corals and had a devastating effect on dolphin reproduction. Continue reading “Study says old, weathered oil from spills is even more toxic to fish than fresh crude”

Warming oceans seen as main cause of glacier meltdown on the Antarctic Peninsula

Disintegration of ice shelves in East Antarctica could result in a spiraling increase in sea levels. PHOTO BY BOB BERWYN.
Warming ocean water is creeping up the continental shelf around the Antarctic Peninsula and melting glaciers in some parts of the region. @bberwyn photo.

Staff Report

British researchers say regional patterns of melting of glaciers on the Antarctic Peninsula are linked with warming oceans in the region. The Antarctic Peninsula is one of the biggest contributors to sea level rise, so the new finding will help pinpoint how fast and how high seas will rise in the decades ahead.

The southernmost glaciers flowing to the coast on the western side of the Peninsula are retreating rapidly, but those in the north show little change, the scientists said in a new study published last week in the journal Science. Since accurate measurements started in the 1940s, 94 percent of the 674 glaciers in the region have retreated. Continue reading “Warming oceans seen as main cause of glacier meltdown on the Antarctic Peninsula”

New report shows how global warming will affect birds and reptiles in the Southwest.

 red-tailed hawk
Global warming will take a toll on reptiles and birds in the Southwest. @bberwyn photo.

Many bird species could lose between 78 and 85 percent of their existing habitat

Staff Report

Birds and reptiles in the Southwest that live in fragmented habitat will be hit hardest by global warming in the decades ahead, according to a new study by scientists with the U.S. Geological Survey and the Northern Arizona University.

The researchers took a close look at about 30 different animals, including well-known species such as the Gila monster, horned lizard, chuckwalla, Sonoran desert tortoise, pinyon jay, pygmy nuthatch, sage thrasher and black-throated sparrow.

A few species could see their habitat expand as the climate warms, but many others will be hit hard by global warming. Most climate models project temperatures to increase by about 6 degrees Fahrenheit in the Southwest in the next century, while precipitation is expected to decline by between 5 and 20 percent. Continue reading “New report shows how global warming will affect birds and reptiles in the Southwest.”

New study tracks origins of the Pacific ‘ warm blob’

El Niño a key factor, but global warming to increase marine heatwaves

Marine heatwaves are becoming more frequent and widespread.
Marine heatwaves are becoming more frequent and widespread.

Staff Report

A disruptive ocean heatwave in the northeastern Pacific Ocean in 2014 and 2015 was probably a manifestation of El Niño, says a new study by scientists with the Georgia Institute of Technology and the National Oceanic and Atmospheric Administration (NOAA).

Such warm-water events could become more common as heat-trapping pollution continues to increase in the atmosphere, according to the findings published in the journal Nature Climate Change. Continue reading “New study tracks origins of the Pacific ‘ warm blob’”