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Arctic permafrost thawing faster than ever

Permafrost in the Arctic is thawing faster than ever, according to a new US government report that also found  Arctic   seawater is war...


sabato 15 agosto 2015


È ormai risaputo che i cambiamenti climatici sono assai deleteri per le biodiversità di tutto il mondo e che a sopravvivere sono solo le specie che riescono ad adattarsi velocemente o che sono più predisposte e resistenti. Tra gli esseri più a rischio del micro mondo ci sono le farfalle

Uno studio inglese ha infatti dimostrato che alcune specie risentono particolarmente delle alte temperature e in particolare della siccità. 

Si è infatti registrato un sensibile calo della popolazione di alcuni tipi di farfalla, dopo un lungo periodo siccitoso nel 1995 a oggi; sono due i motivi che hanno causato questa drastica diminuzione nella popolazione delle farfalle: il primo è la diminuzione di habitat adatti alla riproduzione (agricoltura intensiva e urbanizzazione), il secondo è il surriscaldamento del clima.

Lo studio evidenzia anche che se non si interverrà rapidamente con dei provvedimenti drastici che vadano a controllare l'emissione di gas serra e la salvaguardia regionale del territorio, entro il 2050 si potranno perdere alcune delle specie, già oggi ad alto rischio estinzione. Scenario ancora peggiore per il 2100.

The Green Veined White butterfly is one of the species at risk of extinction from drought

Global warming could drive drought sensitive butterfly species to extinction in the UK by 2050, according to new research.
Scientists found that even the lowest expected levels of warming could decimate populations.
However the researchers found that restoring connections between butterfly habitats could help modify the worst impacts.
The research has been published in the journal Nature Climate Change.
Although many people believe that butterflies are creatures that love the warmth, periods of extremely hot and dry weather can significantly reduce populations.
In this study, British researchers looked at the impact of an extreme drought event in 1995 on butterfly species. This was the most arid summer since records began in 1776.
They identified six species, including the Cabbage White and the Speckled Wood butterflies, that were particularly sensitive to heat.
They then looked at what might happen to these creatures under different levels of warming up to 2100.
If emissions of carbon dioxide continue on a "business as usual" model, and warming is more extreme, then extinctions of some of these species could begin in England as early as 2050.
"We looked at the extent to which populations crashed from the drought and how long it takes them to recover," said lead author Dr Tom Oliver from Nerc Centre for Ecology and Hydrology.
"What we're asking is, as droughts become more frequent whether the return time of the drought was more frequent than the recovery of the butterflies."
"And when that was the case you'd get this gradual population erosion and in those places you'd get local extinctions."
The researchers say that areas of the south east of England would be worst affected.
However they argue that under less extreme warming conditions, changes to butterfly habitats could ameliorate the worst impacts.
The team found that restoring connections between habitats that have been fragmented by human activities such as agriculture, was capable of making a big difference.
Under a low emissions scenario, bridging these connections could improve the probability of butterfly survival by 50%.
"If our habitats are very fragmented, the impacts will be much more severe. In places where it isn't those populations might persist," said Dr Oliver.
"It allows us to buy time until we get those global emission cuts in place."
The researchers believe their study is a conservative estimation of how warming might impact these fragile species.
They are concerned that, because of landscape changes in the UK throughout the 20th century, populations of some of the threatened species might be too low for them to recover from frequent droughts.
The authors say that even people who are not impressed by the aesthetic appeal of butterflies should still be concerned about their demise.
"Butterflies are important culturally as part of our natural heritage, but there are other functions that could be impacted by their extinction including pollution, pest control and decomposition of waste," said Dr Oliver.
"Those un-swayed by the beauty and importance of having butterflies in the countryside ought to be concerned about the disruption to these functions provided by these species."

Global warming threatens extinction for UK butterflies Matt McGrath BBC News 10 August 2015

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