Cropland expansion is biodiversity loss
RAPID CROPLAND expansion is the main cause of biodiversity loss in tropical countries, a study by UNEP’s (the UN Environment Programme) World Conservation Monitoring Centre and the Cambridge Conservation Initiative has found. The study, published in PLOS ONE, highlights maize and soybean as the most expansive crops and as the main drivers of biodiversity loss in tropical regions. Other crops that pose a major threat to habitats and wildlife are beans, cassava, cowpea, groundnut, millet, oil palm, rice, sorghum, sugarcane and wheat, the study says. It estimates that cropland in tropical countries expanded by 48,000 square kilometres per year from 1999 to 2008, with Brazil, Ethiopia, Indonesia, Nigeria and Sudan experiencing the greatest expansion. Stuart HM Butchart, a UNEP researcher and one of the authors of the study, says: “Unsustainable agriculture is the most significant threat to biodiversity, but conservationists have not previously paid much attention to quantifying which particular crops have caused the greatest problems, nor which ones may do so in the future. This [study] starts to address this issue”. One example of crop expansion cited in the study that has quickened the rate of species extinction is the Mega Rice Project in Kalimantan, Indonesia. Vast tracts of peat swamps were drained starting from the late 1990s in misguided attempts to turn them into rice plantations. More than one million hectares, an area about a third the size of Belgium, have been converted for rice production, threatening the survival of Borneo’s last orangutans. Similarly, peat and forest areas gave way to oil palm in Indonesia and Malaysia while soybean expansion has also replaced habitats of particularly high biodiversity value in the Brazilian Cerrado savanna. Expanding maize cultivation also threatens the dry forests of Madagascar. Krystof Obidzinski, a scientist at the Centre for International Forestry Research, in Bogor, Indonesia, says that large-scale land acquisition is proceeding apace in countries like Indonesia — with economic benefits dominating the agenda while environmental impacts appear to be underestimated. If the pace of expansion continues, the report warns, it could derail progress towards meeting the Aichi Biodiversity Targets, a set of 20, time-bound measurable targets aimed at halting global biodiversity loss by the middle of the century. Butchart believes there should be a system in place so that consumers can make informed choices about the food they buy and how sustainably they have been produced. Such a system could reduce and minimise impacts of agriculture on biodiversity. Customers can then discern which products are least damaging to the environment and producers have an incentive to minimise their negative impacts. The study highlights the urgent need for more effective sustainability standards and policies addressing both production and consumption of commodities including robust land-use planning in agricultural frontiers, establishment of new protected areas or REDD+ projects in places agriculture has not yet reached, and reduction or elimination of incentives for land-demanding bioenergy feedstocks. (SciDev)
New model to forecast Asian monsoon better
RESEARCHERS HAVE developed a more accurate model for predicting the amount of summer rainfall and number of tropical storms in East and South-East Asia. The study published in Proceedings of the National Academy of Sciences, advances understanding of the East Asian summer monsoon, a weather system that affects agricultural production and the lives of billions of people across the continent. Researchers say the model could “significantly improve” monsoon and rainfall predictions in the region, which could aid governments and disaster-management specialists. Bin Wang, a meteorology professor at the University of Hawaii, United States and the study’s lead author, says the new model is roughly twice as accurate in predicting rainfall and tropical storms in the summer months over East Asia compared with similar models developed over the past 30 years. According to Wang, the predictions will be more accurate in mainland South-East Asia than in inland China, where colder fronts mix with tropical weather systems and oceans regulate land temperatures to a lesser extent. The study sampled data collected from 1979 to 2009 to analyse the ‘Western Pacific Subtropical High’ (WPSH), a circulation system centred in the Philippine Sea that leads to precipitation and storms in East and South-East Asia. The WPSH is largely influenced by springtime sea surface temperature fluctuations in the Pacific and Indian Oceans. By measuring these influences, the model can predict weather patterns for a given year across a wide area stretching from 5 to 40 degrees north of latitude, and from 100 to 140 degrees east of longitude, according to Wang. Researchers noted that when the WPSH pressure is strong in the summer, monsoon rainfall tends to be above average over East Asia, but fewer storms make landfall in the western North Pacific. “They have made a breakthrough,” says Kyung-Ja Ha, a professor at Pusan National University in South Korea. “I believe that their work will give some insightful ideas to other monsoon scientists, stakeholders and policymakers.” But she notes that the model will need to be updated to take into account the effects of climate change. The UN’s Intergovernmental Panel on Climate Change reports that natural and human-induced climate change will increase the frequency of heavy precipitation and the average severity of tropical cyclones during this century. However, it also says that there is a 66 to 100 per cent chance that the number of tropical cyclones will either fall or stay constant. (SciDev)
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