Climate – On Wisconsin For UW-Madison Alumni and Friends Mon, 17 Sep 2018 15:53:15 +0000 en-US hourly 1 Mammoth Island Fri, 04 Nov 2016 18:00:22 +0000 istock_54252888_large


By ten thousand years ago, woolly mammoths had gone extinct from mainland Asia and North America. But a population of island-dwelling mammoths survived on a remnant piece of land once part of the Bering Strait land bridge.

UW geography professor Jack Williams and graduate student Yue Wang MS’13 contributed to a new study that provides clear evidence of the mammoth extinction on tiny St. Paul Island around 5,600 years ago. A lack of freshwater and changing environmental conditions, including rising seas, drove the demise. The researchers say the findings have implications for low-lying islands, and the people and animals that live on them today.

“I can’t think of any other case where freshwater availability was the driver of extinction,” says Williams, who is also director of the UW’s Center for Climatic Research. “On small oceanic islands, freshwater can be a limited resource.”

Williams and collaborators from across the United States rode snowmobiles to one of the few sources of freshwater on the island off the coast of Alaska, a crater lake surrounded on three sides by steep rock walls. The scientists drilled through the frozen lake surface and took samples of sediments beneath the lake floor, which provided snapshots of the environment through time.

The UW researchers focused on the island’s vegetation and ruled out changes to their food sources as contributors to the mammoths’ extinction. However, sediment cores showed mammoths likely stripped the area around the lake of vegetation, potentially speeding up erosion and harming water quality.

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Climate Change to Last Millennia Fri, 27 May 2016 14:27:22 +0000 flood waters


The changes that are altering Earth’s climate will have much longer-lasting effects than previously realized, according to a study released in February. Looking at climate and oceanography models, the study’s authors believe that it could take as long as 1 million years before all of the carbon currently being released into the atmosphere is completely removed.

“It’s really a perspective piece,” says Shaun Marcott, an assistant professor of geoscience and one of the contributing researchers. “When most people look at climate change, they’re looking at a perspective of how things will be in 2100. If they’re looking long term, they might mean 2300. But we’re looking at climate change on a geological scale — how things will be in ten thousand years or more.”

The effects of burning fossil fuels, the study contends, will not be fully realized for several decades, nor will they dissipate soon after the use of carbon-based fuels ends. Carbon in the atmosphere will cause temperatures to warm, ice caps to melt, and sea levels to rise.

“Temperature is actually the lesser effect. We have some ability to adapt to higher temperatures,” says Marcott. “But the rising sea levels — we can’t adapt to water. We can’t stop it. We can’t mitigate it.”

Marcott and his colleagues forecast that the sea level will rise about forty meters during the next ten thousand years, enough to flood New York, Tokyo, Shanghai, Cairo, most of Florida, and much of Bangladesh. “This will mean that the populations of whole countries will have to move into other countries,” he says. “The conflict in Syria has dislocated 5 million people. What happens when it’s 60 million to 70 million Bangladeshis who no longer have a home? That will cause a lot of conflict.”

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One Word: Subnivium Thu, 29 Aug 2013 18:48:47 +0000 (sub-NIV-ee-um)

The microclimate region that exists beneath the snow. In spring 2013, UW Professor Jonathan Pauli authored a report in the journal Frontiers in Ecology and the Environment noting that the subnivium — a winter “haven for insects, reptiles, amphibians, and many other organisms” — is shrinking due to climate change. Snow cover in the northern hemisphere is as much as 3.2 million square kilometers smaller than it was in 1970. “Snow cover is becoming shorter, thinner, and less predictable,” said Pauli. “We’re seeing a trend. The subnivium is in retreat.”

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Hot Enough for You? Sat, 10 Nov 2012 22:00:59 +0000 Statistics indicate heat waves are the deadliest weather.

Blizzards are bad. Hurricanes are worse. But when it comes to killing power, no weather packs the punch of a heat wave, according to the numbers that Richard Keller has crunched.

Keller, an associate professor in the School of Medicine and Public Health, has been counting the dead from the heat wave that struck France in August 2003. That month, high temperatures in Paris climbed above 100 degrees Fahrenheit, with lows in the eighties. During that stretch, the nation saw its mortality rate shoot up by nearly 15,000 deaths.

“In terms of mortality, this is probably the worst natural disaster in the modern history of France,” Keller says, though he admits, “there may have been some droughts in the Middle Ages — accurate numbers are very hard to get from pre-modern times.”

Accurate numbers are difficult to get in modern times, as well, Keller notes. When some natural disasters hit, the death toll is fairly easy to count: bodies drowned in a flood, for instance, or crushed by falling buildings in an earthquake. But heat is a more insidious killer.

“You can only tell if a person dies of heat stroke if you’re actually there when they die,” Keller says. “Plus, during a heat wave, more people die of things like drowning — the warmer it is, the more people go swimming, and when more people swim, more people drown.”

Keller used numbers that French demographers came up with to measure excess deaths — that is, the total number of people who died in France in August 2003, as compared to the average number of deaths in the same month in 2000, 2001, and 2002. The result was an increase of 14,802. “It’s a crude measurement, extremely blunt,” he says, but it’s the best overall calculation. Across Europe, the heat wave may have accounted for 70,000 excess deaths.

It wasn’t the daytime highs that seemed to be most deadly, Keller believes, but rather the low temperatures — which were actually very high, meaning that people who suffered all day found no relief at night.

“The houses in France, made of stone and brick, just retain heat,” he says. “People had no chance to recover.”

Today, France — as well as communities across the United States and elsewhere — pay greater attention to the danger of heat waves, mandating air conditioning in nursing homes and senior living facilities, and setting up “cooling centers” where the public can have access to air-conditioning. But Keller notes that such measures may have little effect.

“The people who were most affected by the heat were the socially vulnerable: the elderly, the poor, and those who live alone,” he says. “They often don’t take advantage of cooling centers or have people to look in on them and encourage them to seek relief.”

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