At the start of every season, fashion magazines are full of glossy spreads encouraging consumers to splash out on brand new clothes. But at what cost?

The United Nations calls the $2.75 trillion fashion industry “an environmental and social emergency”. The industry produces nearly 20% of the world’s waste water and around 10% of global carbon emissions. It takes 20,000 litres of water to make just one T-shirt and one pair of jeans.

The fashion industry produces almost a fifth of the world’s waste water.

The scale of consumption has led to climate activist group Extinction Rebellion calling on people to boycott fashion for a full year, while in the UK, Oxfam is asking customers not to buy any new clothes during Second Hand September.

Here are 4 more things you can do to shop sustainably...

1) Always read the label

The recently signed G7 Fashion Pact commits some of the world’s biggest fashion companies to reducing the industry’s impact on the environment.

Some leading brands already produce sustainable lines, but a label certifying clothing as organic or sustainable is a good sign that it has an ecologically friendly background.

Only textile products that contain a minimum of 70% organic fibres across the supply chain - from harvesting through manufacturing - are eligible for certification by the Global Organic Textile Standard.

Labels from the Better Cotton Initiative show that clothes are made with cotton using less water and harmful chemicals.

2) Look for low-impact materials

Many of the materials used to make clothes are bad for the environment. Polyester, nylon and acrylic are made from petrochemicals and can release microfibres into the water during the washing process. The chromium used for tanning leather is also highly toxic.

Recent innovations in the materials industry have led to the use of natural proteins to create fibres and fabrics. Mylo is produced from fungal threads and can be made into a durable (and biodegradable) leather-like fabric. Because it can be manufactured so quickly, there is less environmental impact than with traditional materials.

Mylo and Microsilk, which is made from yeast and mimics spider silk, have already been used by clothing designers.

Bolt Threads is creating sustainable, naturally sourced new fabrics. Source: V&A

3) Transform and upcycle

According to the Ellen MacArthur Foundation, customers around the world miss out on $460 billion of clothing value per wear each year by throwing away usable clothing. Some garments are thought to be discarded after just seven to 10 wears.

There may be clothes in your wardrobe that no longer fit, or that need a little extra attention to bring them back to life. A trend for upcycling used items has led to a surge in the do-it-yourself reworking of tired clothes - by fixing the size, or transforming them into something else entirely, like cushion covers or curtains.

4) Don’t trade up, trade in

Several major retailers offer clothing donation programmes where you can leave your unwanted clothes to be sold in secondhand shops, reused in different countries around the world or recycled to make new material.

All of these alternatives prevent your clothes from ending up in landfill - which is what happens to an estimated $175 million worth of clothing in the UK each year.

As an added incentive, customers who bring in contributions of used fabrics are typically given a discount on future purchases.

So you can save up for those new jeans, one bag of old clothing at a time.