Tag: climate change

Study says current rate of sea level rise is unprecedented in recent history

‘Our study is for sea level what the now well-confirmed famous ‘hockey stick’ diagram was for global temperature’

As global warming drives rising sea levels and more intense storms, some communities are looking to augment their beaches with "imported" sand. like here on Manasota Key in Englewood, Florida.
As global warming drives rising sea levels and more intense storms, some communities are looking to augment their beaches with “imported” sand, like here on Manasota Key in Englewood, Florida. @bberwyn photo.

Staff Report

The global rise of sea level may not be as dramatic or as easily visible as some other signs of global warming like melting glaciers, but it will be one of the most destructive and expensive long-term impacts. With a huge percentage of the world’s population living in coastal regions, society will need to take costly measures to protect people. In some cases, there will no option but to move entire communities away from the rising waters.

While there is still some uncertainty among climate scientists as to the extent of future sea level rise, there is little doubt that the current increase is unprecedented in recent times, according to a recent study by scientists with the Potsdam Institute for Climate Impact Research.

“Our study  is for sea level what the now well-confirmed famous ‘hockey stick’ diagram was for global temperature,” said Stefan Rahmstorf, co-author of the paper on past sea-level rise and Co-Chair of PIK’s research domain Earth System Analysis. “We can confirm what earlier, more local sea-level data already suggested: during the past millennia sea-level has never risen nearly as fast as during the last century.”

The researchers said greenhouse gas emissions have caused at least half of the observed sea level rise in the 20th century, and possibly even all of it.

While the study didn’t break new ground in terms of projections, it’s important to be able to show with great certainty how much sea level will rise, Rahmstorf said.

“The new sea-level data confirm once again just how unusual the age of modern global warming due to our greenhouse gas emissions is – and they demonstrate that one of the most dangerous impacts of global warming, rising seas, is well underway.”

Barring any catastrophic climate feedback loops that could accelerate the meltdown of Arctic and Antarctic ice, the researchers said sea-levels worldwide will rise by 50 to 130 centimeters by the end of this century if greenhouse gas emissions are not reduced rapidly.

“With all the greenhouse-gases we already emitted, we cannot stop the seas from rising altogether, but we can substantially limit the rate of the rise by ending the use of fossil fuels,” said PIK’s Anders Levermann, who specializes in climate adaptation.

“We try to give coastal planners what they need for adaptation planning, be it building dikes, designing insurance schemes for floodings, or mapping long-term settlement retreat.”

Even if the world’s countries live up to the 2015 Paris climate agreement, sea level will rise 20 to 60 centimeters by 2100.

“This is quite a challenge, but less expensive than adaptation to unabated sea-level rise which in some regions is impossible”, Levermann adds. “If the world wants to avoid the greatest losses and damages, it now has to rapidly follow the path laid out by the UN climate summit in Paris.”

The likely future sea-level rise cannot be brought down to just one number, but is represented as a range, which at first sight might seem large.

“The range allows for a risk assessment,” said Ben Marzeion from the University of Bremen, Germany. “Coastal Planners need to know how a reasonable worst-case scenario as well as a well-founded best-case scenario look like to weigh chances and costs. The best available science is now converging towards a common uncertainty range of future sea-level rise. Curbing greenhouse gas emissions now gives us the chance to prevent sea level rise to accelerate further.”

Climate: Arctic sea ice melt slows slightly in July

Experts say record low now unlikely

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Summer sea ice off the east coast of Greenland. @bberwyn photo.

Staff Report

Cool and stormy weather in the Arctic during July slowed the rate of sea ice loss to just below average for the month,  making it less likely sea ice extent will dwindle to a record low, according to the latest update from the National Ice and Snow Data Center. But it all depends on conditions the next few months.

For the month, sea ice extent averaged 2.14 million square miles, the third-lowest for July since satellite records started in 1979. It was only the second month of 2016 that didn’t end with a record-low extent, according to the NSIDC. The sea ice extent in July was 73,000 square miles above the previous record low 637,000 square miles below the 1981 to 2010 long-term average. Through 2016, the rate of decline for the month of July is 28,070 square miles per year, about 7.3 percent per decade. Continue reading “Climate: Arctic sea ice melt slows slightly in July”

July 2016 ranks as 14th-warmest on record for U.S.

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Nearly every state in the lower 48 reported well above-average temperatures for the first seven months of 2016, according to NOAA’s State of the Climate report.

Year to-date is third-warmest, according to monthly climate report

Staff Report

The July temperature across the lower 48 states was 1.6 degrees Fahrenheit above the 20th century average, with month ending up ranked as the 14th warmest on record, according to NOAA’s monthly state of the climate report for the U.S.

The year-to-date is the third-warmest on record for the contiguous 48 states, and continues to track toward the warmest ever for Alaska, federal climate trackers said in the new report. Continue reading “July 2016 ranks as 14th-warmest on record for U.S.”

New guidance requires closer look at climate impacts from activities on public lands

The U.S. is the second-largest producer of coal in the world, thanks in part to massive surface mines like this one in Wyoming. Photo courtesy BLM.
New guidance for federal agencies will require closer scrutiny of climate impacts of developments on public land. Photo courtesy BLM.

CEQ updates NEPA rules with an eye toward greenhouse gases

Staff Report

Public land managers and other federal agency decision-makers will no longer be able to shy away from considering climate change as they consider new projects.

Saying that emissions from any given proposal are only a small fraction of global emissions “is not an appropriate basis for deciding whether or to what extent to consider climate change impacts under NEPA,” the White House Council on Environmental Quality wrote in new guidance that directs agencies to quantify greenhouse gas emissions and to choose alternatives for projects that minimize climate impacts. Continue reading “New guidance requires closer look at climate impacts from activities on public lands”

Climate: 1.5 degrees of warming nearly certain over land

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How hot will it be in 2100?

Stored ocean heat will be released for centuries to come

Staff Report

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.

The study was done by researchers with the UK Centre for Ecology & Hydrology and the University of Exeter and published in the journal Scientific Reports. Continue reading “Climate: 1.5 degrees of warming nearly certain over land”

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.”