Il collasso dell’AMOC diventa un rischio reale Quando un governo considera una corrente oceanica un problema di sicurezza nazionale, significa che qualcosa è cambiato davvero. L’Islanda ha ufficialmente classificato il possibile collasso dell’AMOC — la grande circolazione che porta calore dall’Atlantico ai mari del Nord — come minaccia esistenziale. Una decisione rara. E un segnale forte per l’Europa. Perché l’AMOC è così importante L’AMOC funziona come un gigantesco nastro trasportatore: acqua calda dai tropici sale verso nord, si raffredda, affonda e torna indietro in profondità. È questo flusso a rendere gli inverni europei sorprendentemente miti per la latitudine. Il problema è la velocità del cambiamento. L’acqua dolce proveniente dallo scioglimento della Groenlandia sta “diluendo” l’Atlantico del Nord, disturbando il meccanismo che permette all’acqua salata di affondare. Se l’affondamento rallenta, l’intero circuito si indebolisce. Se si ferma, collassa. Gli scienzia...
Wasted food could play an important role in the future of energy conservation, according to a study published in Environmental Science and Technology. By combining several data sets related to food production, use, and waste, a pair of researchers estimate that we waste about 27 percent of available food on average—and about 52 million US households' worth of energy along with it. While the estimates are a bit rough, the authors note that the entire food production chain may have untapped potential as a source of energy savings.
Estimating the energy involved in food use involves a complex web of calculations, as well as many decisions about what sorts of figures to include. Because of the complexity, attempts at collecting such information are rare, and complete sets of data are still less common.
.jpg)
By overlapping, comparing, and extrapolating over a few different food production and waste data sets, including ones from 1995, 2004, and 2007, the authors of this most recent study found that 27 percent of produced or collected food is wasted. Some of the guiltier food groups were fats and oils (33 percent wasted) and fresh fruits and vegetables (32 percent wasted).
When the authors further estimated the energy used in creating and distributing this wasted food, they come up with a staggering figure: about 2 quadrillion BTUs in 2007 were lost in the name of discarded comestibles. For comparison, the average US household uses about 38 million BTUs (source), meaning the wasted food energy could power about 52 million households.
The authors acknowledge large error margins for many of their calculations, sometimes as much as 20 percent. They also base their extrapolations on the proportion of food wasted to total energy used in various years, without much investigation into whether food producers or distributors have made any efforts at cleaning up their acts. Still, as policymakers struggle to figure out how we're going save energy, not to mention create less waste, it appears the food industry might deserve another look.
Environmental Science and Technology, 2010. DOI: (About DOIs).