Now that the bitterly cold, 10-jumpers-and-winter-coat weather is giving way to something slightly less bleak, fashion is following suit with a hot new trend: step forward the fleece.

At New York Fashion Week, Sandy Liang sent leopard print and camouflage fleeces down the catwalk, as the UK high street retailer Urban Outfitters reports sales of fleece jackets up by just under 50% on last year.

Formerly the preserve of ramblers and wildlife television presenters, the fleece found favour with the fashion crowd at the start of winter, worn by the likes of Generation Z models Gigi Hadid and Kendall Jenner, on top of their crop tops. Both favoured navy and olive versions by the outdoor clothing brand Patagonia. In Paris, rapper of the moment Offset recently ticked off two trends in one with an oversized tie-dye fleece version.

The Y/Project show’s long fleece as part of Paris Fashion Week for spring/summer 2019. Photograph: Victor Virgile/Gamma-Rapho via Getty

Their appeal seems to be twofold. Last year brought the arrival of “gorpcore” – from the acronym “gorp”, which stands for “granola, oats, raisins, peanuts” aka hiking snacks. Hiking boots, bumbags and anoraks were all firm fashion favourites last summer. A transition to fleeces for winter warms was the next logical step. And then there’s the sportswear element, with hiking fast becoming “the new yoga”.

The key, it’s thought, is in their cut and colour. At Ashley Williams, fleece jackets came in pale pink zebra print, while House of Sunny’s fleece pullover jacket in blue continues to prove particularly popular on Instagram – indicating that fashion fleeces are either oversized or cropped or both, but nothing in between. “The update and reinvention of the fleece in modern prints and colours has made it a desirable wardrobe staple again,” says Lizzie Dawson, design director at Urban Outfitters.

A Sandy Liang fleece at New York Fashion Week. Photograph: Amy Sussman/WWD/Rex

But buying into the fleece phenomenon may not earn you environmental kudos. In 2016, researchers at the University of California at Santa Barbara found that, on average, synthetic fleece jackets release 1.7g of microfibres each wash. These microfibres, which are made from plastics, find their way into waterways, where they can poison fish as well as animals higher up the food chain. The National Trust recently said it was looking for alternatives to the fleeces worn by its employees because of concerns about the environmental damage they cause. Some brands, such as Houdini Sportswear, have developed fleece materials (made from post-consumer plastic) which shed five times fewer fibres.

But that’s unlikely to dent the sale of fleeces this season. “Fleece jackets are seeing a real spike in global demand, across all price points,” says Lyst’s communications director Katy Lubin. “Alongside the fleece’s fashion credentials, it’s a turbulent world out there right now; a fuzzly, comfy fleece offers the comfort we need in testing times.”