Tag: climate change

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?”

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.”

Droughts slow Amazon carbon uptake

Study shows rainforest resilience

sdf
How much drought can the Amazon withstand? Photo courtesy NASA Earth Observatory.

Staff Report

After studying the impacts of recent droughts in the Amazon, researchers are warning that the rainforest may gradually be losing its ability to remove carbon from the atmosphere. But their study also shows that the ecosystem is resilient and can recover quickly in between droughts.

The study used data from from droughts in 2005 and 2010, finding that tree growth slowed across the vast forests of the Amazon Basin. Long-term measurements from theRAINFOR network spanning nearly a hundred locations across the Amazon Basin helped show how the rainforest temporarily lost biomass. Both droughts killed many trees, but the 2010 drought also had the effect of slowing the growth rates of the survivors, suggesting that many trees were adversely affected but not to the point of death. Continue reading “Droughts slow Amazon carbon uptake”

Climate: U.S. was record warm in June 2016

Deadly heatwaves and flooding part of emerging pattern of extremes

sdfg
Utah and Arizona reported a record-warm June average temperature, with most other states also coming in above average.

Staff Report

Blistering, record heat in the Southwest helped propel the lower 48 states to a new high-temperature record in June, with an average reading of 71.8 degrees Fahrenheit for the month. That included a new monthly temperature record set in Death Valley National Park, where the average temperature in June was 101.9 degrees Fahrenheit.

The warmest-ever June reading broke the record set during the Dust Bowl era, in 1933, according to NOAA’s National Centers for Environmental Information. The year-to-date is the third-warmest on record, the monthly state of the climate summary report said.

Continue reading “Climate: U.S. was record warm in June 2016”

Climate: Death Valley sets heat record in June

Death Valley heat record
Ripples on Mesquite Flat sand dunes, Photo courtesy Death Valley National Park.

Average temperature for the month more than 6 degrees above the historic norm

Staff Report

The deadly heatwave that spread across the southwestern U.S. in June also brought a new record high average temperature to Death Valley, one of the hottest places on Earth. According to the National Park Service, last month was the warmest June on record in the national park, with the average temperature for the whole month registering at 101.9 degrees Fahrenheit — about 6 degrees above the long-term average.

Death Valley’s average daily high temperature this June was 115.5 degrees Fahrenheit and the average overnight low was 88.2 degrees. In spite of a record-setting average temperature, Death Valley only set a new daily record one day last month, with 126 degrees recorded on June 21, 2016. The highest temperature ever recorded in Death Valley in June was just a few years ago: 129 degrees on June 30, 2013. Continue reading “Climate: Death Valley sets heat record in June”