Stored ocean heat will be released for centuries to come
Warming of at least 1.5 degrees Celsius over most of Earth’s land areas is probably already locked into the climate system — even if greenhouse gas concentrations were capped at today’s levels.
The new climate change warning came from UK scientists who, in a new study, differentiated between the warming over land areas and the average global temperature increases often used in discussions about efforts to limit emissions of CO2 and other greenhouse gases.
“Millions of people around the world should be receiving heat-related warnings and advisories if we are to avoid a repeat of the thousands of deaths which occurred last year from heatwaves notably in Asia and Europe,” said Robert Glasser, the UN Secretary-General’s special representative for disaster risk reduction.
“More effort is required to ensure that the poor and vulnerable including refugees, children, older persons and persons living with disabilities are reached with early warnings and that practical measures are taken to ensure they have access to water and adequate shelter and protection from the heat and the sun,” Glaser said, adding that emergency service managers need to “step up the focus on extreme heat” to reduce mortality. Continue reading “UN warns of heatwave health risks”→
Study says disastrous tipping points could be reached by 2050
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”→
Migration changes could affect competition for nesting sites
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.”
New study suggests tropical storms will become more intense
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?”→