AS Bob Dylan almost said – “One more cup of coffee before consumption outstrips production in the valley below…”

And as the great man never sang: “One more cup of tea before the Darjeeling crop shrivels and dies…”

Tea was our national drink until coffee mugged our mugs. Perhaps tea does still rule in the home, but not out on the streets. Here in York coffee shops spring up all the time. Park your car for too long and you’ll return to find it’s been turned into a coffee shop.

The insatiable demand for coffee combined with difficulties caused by global warming – and, yes, it’s happening Donald, so stop muttering through your cheese-burger mouth – put great pressure on the coffee crop.

In June, it was reported that consumption was forecast to outstrip production for the third year in a row, according to the International Coffee Organisation, an intergovernmental body that looks after coffee.

A coffee shortage or price rises have been avoided so far, thanks to stockpiles built up during good years. But a pile of beans only lasts so long, and as exporters have been digging into their stock, levels of coffee are said to be low.

Dr Tim Schilling is director of the World Coffee Research Institute, which is funded by the global coffee industry – and, indirectly, by all those cappuccinos I buy. He told the BBC website: “The supply of high-quality coffee is severely threatened by climate change, diseases and pest, land pressure, and labour shortages – and demand for these coffees is rising every year.”

Especially hit are good quality coffees – just the sort I choose, dammit.

A picture on the BBC website shows a woman crouching to harvest coffee beans in Ethiopia. Such a livelihood is at threat thanks to global warming, as coffee growing areas in Ethiopia could decrease by up to 60 per cent if temperatures rise by 4C by the end of the century. This is according to a study by Kew Gardens and collaborators in Ethiopia.

That crouching woman is a reminder that our daily treats and pleasures often come at the cost of someone far away doing hard work for little money.

Picking the tea harvest is fiddly and difficult work, and two years ago a BBC investigation found dangerous and degrading living and working conditions on tea estates in Assam.

Those ‘tips’ don’t get into your teabags all by themselves, and the people at the end of the tea chain can suffer horribly. BBC Radio 4’s File on Four discovered that “living and working conditions are so bad, and wages so low, that workers and their families are left malnourished and vulnerable to fatal illnesses”.

This is why we should worry that Sainsbury’s and others appear to be stepping away from the Fairtrade mark that guarantees decent payment and treatment of workers.

As it happens, Sainsbury’s is one of the places where I buy Darjeeling, along with Waitrose. Sadly, neither shop is a regular visit due to geography and price constraints. I do love a good cup of Darjeeling, although loose leaf golden breakfast tea stands in when supplies run out.

Today it is reported that the Darjeeling crop is under threat. Darjeeling is known as the “champagne of teas” – or, to unbelievers, as that weak stuff you can’t stand a spoon in. It can be horrendously expensive. I suspect the packets I buy are from the bottom of the Darjeeling tea chain.

The tea is grown in the foothills of the Himalayas in West Bengal state. Since June, Darjeeling has been riven by violent protests and strikes in support of a campaign demanding a separatist campaign by the Nepali-speaking Gorkha community. And the crop is going unpicked.

As a person who doesn’t operate well without his tea and coffee, I am sorry to bring all this up. Better to sip and swill, to grind and guzzle, without a thought for the wider world. But sometimes the wider world threatens to take away your daily treats.

My wife works in a health food shop and she used to bring home lovely bags of Brazil nuts. Then the crop failed a few times.

“Did you know that they have to go into the jungle to pick them?”

“Well, yes you told me that – but they’re delicious. And aren’t they meant to be good for men or something?”

Anyway, those nuts have become too expensive to buy unless you’ve won the Lottery, or unless you are Prince Charles or someone.

This blog has been fuelled by one mug of tea and now the tank is empty.