Quickly: In case you had any doubt about the causes of high levels of Arctic sea ice melting we've seen in recent years, a new study sorts it all out. At minimum, 70% of the melting can be attributed to human activity and climate change. Note, 'at minimum'. At the high end, the amount of melting that can be attributed to human activity may be 95%.
The Guardian quotes study lead author Jonny Day, from the University of Reading, saying that at most 30% of the observed melting can be because of natural cycles.
Compared to previous research, this study increases significantly the amount of melting tied to anthropogenic climate change. Previous studies showed about half of the melting could be tied to human activity.