The government of Cusco in the Peruvian Andes is scheduled to ban all genetically modified varieties of potato. Nature reports the area was the birthplace of many kinds of potatoes, and is still home to thousands of varietals. The move was supported by Peruvian non-profit Association ANDES, along with the London-based International Institute for Environment and Development. The hope is to ensure that genes from GM potatoes don't infiltrate native potatoes, and to promote the area as a source of diverse, authentic, organic potato varieties. Association ANDES has been involved in repatriating varieties of potato that have gone locally extinct, but are held in repositories such as the International Potato Center in Lima. "When the potatoes came back, the culture came back," says Alejandro Argumedo. "Genetic diversity and cultural diversity are closely linked." JULIA WHITTY

A new study in the southeastern U.S. suggests that increased vine growth is changing bottomland hardwood forests. Researchers from Ohio State University charting the growth of grapevines, trumpet vines, poison ivy, and Virginia creeper in two South Carolina forests found as much as a 10-fold increase in just two decades. As the vines increase, the density of small trees decreases, probably because most vines use adhesive roots or tendrils to climb trees. The reasons for the shift aren't yet understood, but rising CO2 levels may be to blame &mdash since other studies suggest that vines such as poison ivy benefit more than trees from higher CO2 levels. . . Think of that itchy future: the Republican rash. JULIA WHITTY

First, let this be said: Lewis Gordon Pugh may be crazy. Known as the "Ice Bear", the record-setting swimmer has repeatedly subjected his body to the extremes of human endurance in lakes and oceans the world over. He holds long-distance swimming records for the Atlantic, the Indian, the Pacific, and the Arctic. According to his Wikipedia entry, he shares with the nine-banded armadillo the ability to regulate his internal body temperature at will. It was this particular skill that was on display last Sunday when he became the first human to undertake a long distance swim at the North Pole. For 18 minutes and 50 seconds, Pugh splashed through waters that have thawed to a pleasant 28.7 degrees Fahrenheit. "The water was absolutely black," he told the BBC. "It was like jumping into a dark black hole. It was frightening. The pain was immediate and felt like my body was on fire. I was in excruciating pain." What fun! So, why did he do it? To highlight climate change. The location of Pugh's swim was, until recently, a block of ice. But as global temperatures have risen, much of the polar ice cap has melted. As Pugh explained to Britain's ITV, he finished his swim with mixed emotions. "I am obviously ecstatic to have succeeded, but this swim is a triumph and a tragedy—a triumph that I could swim in such ferocious conditions, but a tragedy that its possible to swim at the North Pole."

UN Secretary General Ban Ki-moon said on Monday he would press President Bush over climate change when they meet in Washington on Tuesday, Reuters reports. "On climate change, I'm encouraged by a high level of expectations as well as representation on that special high level meeting on Sept. 24," Ban said, referring to a conference on the environment that he has called for September on the sidelines of the annual UN General Assembly. "I would like to discuss this matter with President Bush and would expect President Bush and the American administration will be represented at the highest possible level." JULIA WHITTY

The Paris city council is launching a free bike scheme to encourage people to give up the motor in favor of pedal power. The BBC reports this morning that the local authority in Paris is depositing 20,000 heavy-duty bicycles, called Velib, in 750 or so special racks around the city and anyone who wants one simply swipes his or her public transport card and pedals off wherever they want to go. The bike can be returned to any Velib stand. Subscriptions range from one day (one euro, $1.38) to a whole year (29 euros, $40). The first half hour of pedalling time is free but if you fail to return the bike after 30 minutes you get charged an extra euro and the penalties go up over time. The scheme has worked well in the French city of Lyon. But out of 2 million Parisians, only 150,000 own bikes. (Other Europeans don't need encouragement.) Tourists will love them and every city should have them. After all, why not use that fastest-growing and INFINITE fuel source: fat. JULIA WHITTY

A Canadian team reports in this week's Science that efforts to crack down on persistent organic pollutants (POPs) may have missed an entire set of them. Dioxin, PCBs, and DDT are considered among the most dangerous pollutants on the planet because they don't break down easily, are highly toxic, and build up in the food chain. These chemicals persist in our body fat, and even miniscule amounts in food can add up over time and contribute to health problems such as cancer. More than 140 countries have endorsed the 2001 Stockholm Convention, which aims to banish a dozen POPs from the environment. The Convention's target list is based on risk assessments of these POPs accumulating in fish food webs. But that assumption, the authors argue, could be missing chemicals that fish remove from their bodies but that mammals and birds don't, due to their different respiratory physiology. One-third of the 12,000 or so organic chemicals on the market in Canada fit this new category. . . Whoa. Here comes Silent Spring, Summer, Fall & Winter. JULIA WHITTY

Many birds have dwindled because of radiation from the nuclear power plant accident in Chernobyl. Yet a new study in the Journal of Applied Ecology, reported by the AAAS, finds that some species are declining at a far greater rate. The greatest decline is in brightly colored species (orioles, blackbirds, and blue tits) inhabiting high radiation zones. Migrant birds are also faring worse than residents. Both groups possess high levels of antioxidants &mdash a substance needed to protect against radiation sickness &mdash but which the authors suggest may be in short supply in birds maintaining bright plumage and/or birds sustaining their metabolism during long migrations. . . Yet another blow to biodiversity. JULIA WHITTY

Last July was a scorcher in California. The state has officially reported that the record temperatures killed about 150 people. But an AP analysis of death counts by county reveals that nearly 500 more people died that month than normally do in July. The study did not find evidence of a cover-up, but that's not good news. States don't yet have the tools to determine what constitutes a weather-related death, meaning that many more will have to die before climate change is recognized as an urgent public health problem.

Routine feeding of antibiotics to livestock may be contaminating the world of plants. Researchers at the University of Minnesota have evaluated whether food crops accumulate antibiotics from soils spread with manure that contains antibiotics. Plant uptake was evaluated in a greenhouse study involving three food crops: corn, lettuce, and potato. Plants were grown on soil modified with liquid hog manure containing Sulfamethazine, a commonly used veterinary antibiotic. This antibiotic was taken up by all three crops. Concentrations of antibiotics were found in the plant leaves. Concentrations in plant tissue also increased as the amount of antibiotics present in the manure increased. It also diffused into potato tubers, which suggests that root crops, such as potatoes, carrots, and radishes, that directly come in contact with soil may be particularly vulnerable to antibiotic contamination. JULIA WHITTY

Organic farming can yield up to three times as much food as conventional farming on the same amount of land. A new study from the University of Michigan refutes the long-standing assumption that organic farming methods can't produce enough food to feed the global population. The researchers found that yields in developed countries were almost equal between organic and conventional farms, while food production in developing countries could double or triple by going organic. The study also found that equal or greater yields could be accomplished using existing quantities of organic fertilizers, and without putting more farmland into production. Ivette Perfecto, of U-M's School of Natural Resources and Environment, said the idea that people would go hungry if farming went organic is ridiculous. "Corporate interest in agriculture and the way agriculture research has been conducted in land grant institutions, with a lot of influence by the chemical companies and pesticide companies as well as fertilizer companies—all have been playing an important role in convincing the public that you need to have these inputs to produce food," she said. JULIA WHITTY