Archive for March, 2013

Covering up Damages of Oil Spill; an Effort in Vain


Census: Economy slows U.S. population growth

Haya El Nasser and Paul Overberg,  USA TODAY3:31p.m. EST December 12, 2012

The U.S. population will be older and smaller than had been predicted just four years ago.

The Great Recession may be over but the repercussions will echo for decades by braking the nation’s population growth and steering it on an unprecedented path, the Census Bureau predicted Wednesday.

Fewer immigrants and fewer babies — a decline caused largely by the poor economy and high unemployment — are shifting the shape of the nation’s population: It will be older and smaller than had been predicted just four years ago.

By 2050, the nation is projected to have 399.8 million people — 39 million fewer than the previous predictions during the recession in 2008. The country will now reach the 400 million milestone in 2051 or 12 years later than previously projected, the Census Bureau said.

“The United States is on a new demographic trajectory,” says Mark Mather, demographer at the Population Reference Bureau. “The decline in immigration dampens U.S. population growth in two ways. Fewer immigrants means there are fewer new residents. … But the decline in immigration also reduces the number of potential births.”

Diversity will continue to rise, a trend led by children. By 2019 — four years earlier than expected — no single racial or ethnic group under 18 will be a majority, says William Frey, demographer at the Brookings Institution.

The nation as a whole will reach that point in 2043, a year later than earlier projected.

“The U.S. will become a plurality nation where the non-Hispanic white population remains the largest single group but no group is in the majority,” says Acting Census Bureau Director Thomas Mesenbourg.

“The change is coming much faster for kids than the country as a whole,” says Kenneth Johnson, demographer at the University of New Hampshire’s Carsey Institute. “It’s not just because the minority population of children is growing but also because the number of white children is diminishing.”

Much of the minority increases come from births rather than migration, he says.

Shape of the nation in 2060, according to government projections:

  • The population 65 and older will double to 92 million or one in five residents. The “oldest old” 85 and over will more than triple to 18.2 million.
  • In just eight years, there will be more elderly (65 plus) than schoolchildren. By 2060, the older will outnumber the young for the first time in U.S. history.
  • Baby Boomers will slowly fade away. In 2060, when the youngest would be 96, they will number just 2.4 million compared with more than 76 million now.
  • Whites who are not Hispanic will peak in 2024 at about 200 million and will be the only major racial or ethnic group to decline after that. Their numbers are expected to fall more than 20 million from 2024 to 2060.
  • The number of Hispanics will more than double from about 53 million to almost 129 million. Nearly one in three Americans would be Hispanic compared to about one in six today. Asians will more than double too, reaching 34.4 million.The black population will increase from 41 million to about 62 million.
  • Blacks’ share of the population will inch up from 13.1% to 14.7%.


Despite the slowdown in population gains — annual growth is expected to drop from almost 1% in 2010 to 0.77% in just three years — Mather does not expect the U.S. population to decline this century. 

    “We’re nowhere near Japan or some of the other countries with low fertility rates,” he says. “But these numbers show we are headed in that direction.”

Have you heard the one about the little termite that could, and did, take on a desert and turn it green? At least a little greener, except for those spots.       

Walter R. Tschinkel

A fairy circle in the grasslands of Namibia, close up.                           

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The reddish barren spots, thousands of them, are called fairy circles, the name itself an invitation to try to solve the mystery of their origins. They dot a narrow belt of desert stretching from Angola through Namibia into northern South Africa. For no obvious reason, the round patches of sandy soil interrupt the arid grassland, like a spreading blight on the land.       

To the Himba people who live in the region, however, there is nothing to explain. That’s just how it is, they tell anthropologists; the circles were made by their “original ancestor, Mukuru,” or more poetically, they are “footprints of the gods.” A just-so story blames a mythical dragon that lives in a crack deep under the earth. The dragon’s poisonous breath kills vegetation to create the circles. Trouble is, some scientists point out, the bad-breath hypothesis apparently originated with fanciful tour guides.       

New research may now have yielded a more credible explanation for the fairy circles as examples of natural ecosystem engineering by a particular species of sand termites, Psammotermes allocerus. A German scientist reported on Thursday that most likely these industrious termites were the agents for making much of their desert home an oasis of permanent grassland.       

In an article in the journal Science, Norbert Juergens, a professor of ecology at the University of Hamburg, said these termites “match the beaver with regard to intensity of environmental change, but surpass it with regard to the spatial dimension of their impact.”       

Over the 1,200-mile length of the Namib Desert, especially in parts of Namibia, Dr. Juergens wrote, “P. allocerus turns wide desert regions of predominately ephemeral life into landscapes dominated by species-rich perennial grassland supporting uninterrupted perennial life even during dry seasons and drought years.”       

Last year, Walter R. Tschinkel, a biologist at Florida State University, published an analysis of aerial and satellite photography and other research to describe the number, size and dynamics of these formations. Some are as small as six feet in diameter and never grow much bigger. The largest ones can be at least 40 feet across. It was estimated that the smaller circles have average life spans of 24 years, the larger ones as much as 75 years.       

But Dr. Tschinkel had first assumed that termites were implicated and went looking for nests of a different species, harvester termites, without success. He finally concluded that no other termites had been associated with the circles, and seemed resigned to a mystery unsolved.       

In a critique, Dr. Tschinkel said he was unconvinced that the termites are the cause of the circles. He said the paper by Dr. Juergens “has made the common scientific error of confusing correlation (even very strong correlation) with causation.”       

Scientists at the University of Pretoria in South Africa have also tested hypotheses of escaping natural gases like methane or other toxins rising to the surface and wiping out vegetation at these spots. But the results have been inconclusive.       

Dr. Juergens said in a telephone interview that Dr. Tschinkel was “looking for the wrong termites and you could easily overlook the ones that were actually living” deep beneath the surface of the red sandy spots, feasting on grass roots to keep the patches of land free of vegetation. In this way, the soil is better able to absorb rainfall quickly, with little water loss due to evaporation. The absence of vegetation at the site also means that rainwater is not lost through transpiration, the evaporation of water from plants.       

The absorbed water, the scientists explained, spreads evenly in the sandy soil all around, which explains the circular patterns. This nourishes the surrounding grassland. And the termites keep chomping the roots of new shoots from beneath the inner circle, preventing new vegetation from disrupting their engineered ecosystem.

Another critical factor, Dr. Juergens said, is that all the circles he and associates examined methodically over 40 field trips in the last six years had two telling characteristics. P. allocerus termites were present in all, and the soil was extremely sandy and porous.       

N. Juergens

The spots dot a narrow belt of desert stretching from Angola through Namibia into northern South Africa.                           

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They found strong evidence, Dr. Juergens said, that the species does “things not done by other termites. They are “quite clandestine,” he noted. They build no nests or mounds above ground. Their underground galleries and passages are deep and narrow. “They sort of swim in the loose sand, not leaving tracks,” he said.       

The researchers observed that the circles occur only in sandy soil, not where clay predominates. And they studied the presence of the termites in the earliest stages of a circle’s formation, establishing that they were in on its creation, not merely occupying it at later stages. They also were involved in widening the diameter of the circles, as they steadily fed on grasses at their outer margins.       

In dry seasons, the termites can remain alive and active by moving out from the circles, still underground, and surviving on roots of the outlying grasses.       

David P. Crandall, an anthropology professor at Brigham Young University in Utah who has studied the Himba people closely since 1990, said the fairy circles “are a strange and interesting phenomenon” that is vital to their sparse population spread over an area about half the size of Arizona. Even though the people appear to have little curiosity about why the circles are there, they depend on the grasses around them to graze their cattle, goats and sheep.       

The Himba sometimes put the barren spots to new uses. Examining some Google maps, Dr. Juergens was puzzled by what appeared to be black margins to the circles in some pictures. Going to the sites, he found that they had erected temporary wooden fences to corral young cattle overnight, as protection against lions and other predators.