The study, published online April 6 in the journal Climate Dynamics, represents a new approach to the question of whether global warming in the industrial era has been caused largely by man-made emissions from the burning of fossil fuels. Rather than using complex computer models to estimate the effects of greenhouse gas emissions, Lovejoy examines historical data to assess the competing hypothesis: that warming over the past century is due to natural long-term variations in temperature.

“This study will be a blow to any remaining climate change deniers,” Lovejoy says. “Their two most convincing arguments — that the warming is natural in origin, and that the computer models are wrong — are either directly contradicted by this analysis, or simply do not apply to it.”

Lovejoy’s study applies statistical methodology to determine the probability that global warming since 1880 is due to natural variability. His conclusion: the natural-warming hypothesis may be ruled out “with confidence levels greater than 99 per cent, and most likely greater than 99.9 per cent.”

To assess the natural variability before much human interference, the new study uses “multi-proxy climate reconstructions” developed by scientists in recent years to estimate historical temperatures, as well as fluctuation-analysis techniques from non-linear geophysics. The climate reconstructions take into account a variety of gauges found in nature, such as tree rings, ice cores, and lake sediments. And the fluctuation-analysis techniques make it possible to understand the temperature variations over wide ranges of time scales.

For the industrial era, Lovejoy’s analysis uses carbon dioxide from the burning of fossil fuels as a proxy for all man-made climate influences.

Although Lovejoy used a different methodology, he said his findings effectively complement those of the International Panel on Climate Change (IPCC).

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Between 1961 and 2007, rising meat consumption and total calorie intake underpinned a 38 per cent increase in the world’s per capita “phosphorus footprint,” the researchers conclude in a paper published online in Environmental Research Letters.

The findings underscore a significant challenge to efforts to sustainably manage the supply of mined phosphorus, a non-renewable resource widely used as fertilizer. When phosphorus is lost through agricultural run-off or sewage systems, it can pollute waterways downstream. In addition, because deposits are heavily concentrated in a few countries, global supplies and prices for the resource are vulnerable to geopolitical tensions.

In recent years, many researchers have explored how human activity has altered the phosphorus cycle in the environment and how management of phosphorus could be altered to ensure long-term sustainability. This new study sheds more light, in particular, on how diet choices have affected the intensity of phosphorus use around the world.

“Our results demonstrate that changes in diet can be a significant part of the strategy for enhancing sustainability of phosphorus management,” says lead author Geneviève Metson, a doctoral student in McGill’s department of natural resource sciences. “In particular, reduced consumption of meat, and especially beef, in countries with large phosphorus footprints could put a big dent in demand for mined phosphorus — since it takes many kilograms of feed, which is fertilized, to produce a kilogram of meat.”

Metson and her co-authors, Professor Elena M. Bennett of the McGill School of the Environment and Arizona State University Professor James J. Elser, computed phosphorus-footprint values based on annual country-by-country diet composition data from the Food and Agriculture Organization. They calculated the total amount of phosphorus applied to food crops for humans and animals by using fertilizer application rates available through the International Fertilizer Association, among other sources. The authors also examined the statistical relationship between economic development and phosphorus-footprint values, and developed scenarios to consider the relative importance of diet changes.

“It is really remarkable how much influence changes in diet have had on our demand for this very limited resource,” Bennett says.

“As research in this area proceeds, it would also be interesting to learn how much of the phosphorus used in food production is able to be recycled and how much is currently reused. Food waste and human waste generally aren’t reused today, but can be a valuable resource if turned into fertilizer or compost for use on nearby agricultural fields.”

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Although vitamin D can be obtained from limited dietary sources and directly from exposure to the sun during the spring and summer months, the combination of poor dietary intake and sun avoidance has created vitamin D deficiency or insufficiency in large proportions of many populations worldwide. It is known that vitamin D has a wide range of physiological effects and that correlations exist between insufficient amounts of vitamin D and an increased incidence of a number of cancers. These correlations are particularly strong for cancers of the digestive tract, including colon cancer, and certain forms of leukemia.

“For years, my lab has been dedicated to studying the molecular mechanisms of vitamin D in human cancer cells, particularly its role in stopping their proliferation,” said White. “We discovered that vitamin D controls both the rate of production and the degradation of cMYC. More importantly, we found that vitamin D strongly stimulates the production of a natural antagonist of cMYC called MXD1, essentially shutting down cMYC function.”

The team also applied vitamin D to the skin of mice and observed a drop in the level of cMYC and found evidence of a decrease in its function. Moreover, other mice, which lacked the specific receptor for vitamin D, were found to have strongly elevated levels of cMYC in a number of tissues including skin and the lining of the colon.

“Taken together, our results show that vitamin D puts the brakes on cMYC function, suggesting that it may slow the progression of cells from premalignant to malignant states and keep their proliferation in check. We hope that our research will encourage people to maintain adequate vitamin D supplementation,” said White.

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Although organic techniques may not be able to do the job alone, they do have an important role to play in feeding a growing global population while minimizing environmental damage, according to researchers at McGill University and the University of Minnesota.

A new study published in Nature concludes that crop yields from organic farming are generally lower than from conventional agriculture. That is particularly true for cereals, which are staples of the human diet — yet the yield gap is much less significant for certain crops, and under certain growing conditions, according to the researchers.

The study, which represents a comprehensive analysis of the current scientific literature on organic-to-conventional yield comparisons, aims to shed light on the often heated debate over organic versus conventional farming. Some people point to conventional agriculture as a big environmental threat that undercuts biodiversity and water resources, while releasing greenhouse gases.

Others argue that large-scale organic farming would take up more land and make food unaffordable for most of the world’s poor and hungry.

“To achieve sustainable food security we will likely need many different techniques — including organic, conventional and possible ‘hybrid’ systems — to produce more food at affordable prices, ensure livelihoods to farmers and reduce the environmental costs of agriculture,” the researchers conclude.

Overall, organic yields are 25 per cent lower than conventional, the study finds. The difference varies widely across crop types and species, however. Yields of legumes and perennials (such as soybeans and fruits), for example, are much closer to those of conventional crops, according to the study, conducted by doctoral student Verena Seufert and geography professor, Navin Ramankutty of McGill and Prof. Jonathan Foley of the University of Minnesota’s Institute on the Environment.

What’s more, when best management practices are used for organic crops, overall yields are just 13 per cent lower than conventional levels. “These results suggest that today’s organic systems may nearly rival conventional yields in some cases — with particular crop types, growing conditions and management practices — but often they do not,” the researchers write.

Improvements in organic management techniques, or adoption of organic agriculture under environmental conditions where it performs best, may help close the yield gap.

“Our study indicates that organically fertilized systems might require higher nitrogen inputs to achieve high yields as organic nitrogen is less readily available to crops. In some cases, organic farmers may therefore benefit by making limited use of chemical fertilizers instead of relying only on manure to supply nitrogen to their crops,” Seufert says. “At the same time, conventional agriculture can learn from successful organic systems and implement practices that have shown environmental benefits, such as increased crop diversity and use of crop residues.”

Yields are only part of a set of economic, social and environmental factors that should be considered when gauging the benefits of different farming systems, the researchers note. “Maybe people are asking the wrong question,” Ramankutty says. “Instead of asking if food is organically grown, maybe we should be asking if it’s sustainably grown.”

The results point to a need to get beyond the black-and-white, ideological debates that often pit advocates of organic and local foods against proponents of conventional agriculture, Foley adds.

“By combining organic and conventional practices in a way that maximizes food production and social good while minimizing adverse environmental impact, we can create a truly sustainable food system.”

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Results from a study last year showed that 19 per cent of high school students received one or more lottery tickets or scratch cards as gifts, of which 86 per cent of these came from family members. These rates fell from a high of 30 per cent in 2004 – perhaps coincidentally the year McGill University began an annual holiday campaign with Loto- Québec out of concerns about adolescent problem gambling.

Working with lottery corporations increases the effectiveness of this very important message. “We ask parents to use their judgment and offer their youngsters gifts unrelated to games of chance,” said Alain Cousineau, president and CEO of Loto-Québec.

Gambling remains a familiar activity for a majority of adolescents, with research suggesting that 70 to 80 per cent of adolescents report having gambled for money in the past year, 30 per cent report gambling on a weekly basis, and current problem gamblers report beginning gambling during childhood, at ages as young as nine or 10.

This year, give the gift of responsibility. The sale of lottery products is reserved to those 18 or 19 years of age and older, depending on the provincial jurisdiction, similar to age restrictions placed on the sale of alcohol and tobacco.

This year, it you choose to offer a lottery product as a gift, remember that gambling is only for adults.

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