Some of the nation's favourite dishes, from fish and chips to chicken tikka masala, could be threatened by climate change, environmentalists warn.
Warmer seas could see populations of cod - long the staple in fish and chips, which dates back to the 19th century - displaced by other species, leading to an "anchovies and chips" fish supper by mid century, WWF said.
Chicken may suffer from worse welfare as the world warms and will have to be fed on alternatives such as algae and insects if soy production is hit by higher temperatures and changes to rainfall, ending the era of cheap chicken.
Other key ingredients of a tikka masala, such as rice, tomatoes and onions could all face price rises and shortages as a result of warmer conditions and changing weather patterns .
In a report published ahead of Earth Hour, a world-wide environmental event, WWF warned other dishes such as cheese ploughman's and lamb cawl - Welsh lamb stew - could also be under threat by 2050.
For a ploughman's, cheese production could be affected by heat stress on dairy herds which could hit milk yields, while wheat crops could see a fall in quality due to water shortages.
Even the apples that make up part of the dish may be softer and sweeter in warmer weather conditions, which may also threaten existing orchards and force growing to move north as trees need a period of cold to ensure yields.
Dairy farmers also face increased volatility in sourcing feed as a result of global changes to weather.
And farmers producing lamb for cawl face an increase in frequent flooding in the UK, which risks sheep welfare and meat production and potato crops could fail due to more widespread infestations.
Other increasingly popular dishes such as "smashed avocado on toast" and even the morning staple for millions, a cup of coffee, are at risk from global warming.
The report also looked at the "carbon footprint" of the four classic dishes, fish and chips, chicken tikka masala, cheese ploughman's and lamb cawl, to reveal the amount of greenhouse gas emissions associated with producing each meal.
It found the most polluting dish was lamb cawl, as a result of the methane produced during digestion by sheep, followed by the ploughman's, due to the methane from the cows needed to produce the milk for cheese.
Producing a lamb cawl creates the same emissions as boiling the kettle for a cup of tea 258 times, while growing and producing the ingredients for a ploughman's needs the equivalent of boiling the kettle 113 times.
The lowest carbon footprint of the dishes was for fish and chips, the report found.
This Earth Hour, which takes place at 8.30pm on Saturday March 24, WWF is urging people to make promises to change their life in one small way to help the environment, such as refusing plastic cutlery, carrying a keep cup or cutting back on meat.
Gareth Redmond-King, head of energy and climate at WWF said: "The threat to these classic dishes just shows that climate change could impact every aspect of our lives in future if we don't act now.
"That's why this Earth Hour we want people to eat more sustainably. That doesn't necessarily mean going vegan or vegetarian - it means each of us cutting back on the amount of fish, meat and dairy.
"If each of us takes a small action, together we can combat climate change and future-proof our best-loved dishes."