Cutting global beef consumption and eating chicken instead would do more to tackle climate change than building two million onshore wind turbines and 2,000 nuclear reactors, according to Government analysis.

Cows and sheep are so bad for the environment that switching just half the beef and lamb in an average diet to pork and poultry could enable the world to hit its global warming targets without using any nuclear plants or wind farms at all.

The figures are drawn from a new “global calculator” online tool, launched on Wednesday by the Department of Energy and Climate Change (DECC).

The software, part-funded by £550,000 of taxpayer cash, is intended to show the possible scenarios in which the world can hit its goals of limiting warming to 2C above pre-industrial levels. Beyond 2C, scientists say the effects of warming will be far more severe.

The goal requires annual global greenhouse gas emissions to be slashed from about 50 gigatonnes of carbon dioxide equivalent now, to about 20 gigatonnes a year in 2050. On current behaviour, the world is on course for about 84 gigatonnes by 2050, leading to global warming of 6C this century.

Most expert analyses show a vast expansion of low-carbon technologies including wind farms and nuclear plants to replace fossil fuels is likely to be needed to hit the targets.

However DECC’s calculator shows that other routes could technically be feasible - if people were prepared to change their behaviour. “Making changes in our lifestyle (for example our dietary and travel choices) can significantly reduce emissions and the effort needed across other sectors,” DECC said.

According to some estimates, beef production results in five times as many harmful emissions as equivalent chicken or pork production, while using 28 times as much land for grazing that might otherwise be used for forestry to help absorb carbon.

DECC works on the more conservative assumption that beef needs four times as much space as poultry, with an area the size of a football pitch used to produce 250 kg of beef or 1,000 kg of poultry.

It assumes that if the world carries on on current trends then by 2050 the global average diet - which is likely to mask huge variations between richer and poorer nations - would include 250g of red meat a week.

Replacing 100g of that with white meat could save 29 gigatonnes of carbon dioxide equivalent a year, it calculates.

The calculation assumes the world population will have grown to 10 billion by 2050, meaning the 100g-a-week switch saves one million tonnes of beef a week. As well as avoiding emissions from those cows, it would free up 1,400 million hectares of land for forests, which help absorb emissions.

Although the 29 gigatonne “meat switching” saving alone would fall short of the emissions reductions necessary to avoid extreme global warming, further changes - for example to transport and product efficiency - could help provide the remaining reductions without any wind or nuclear.

By contrast, if every country in the world were to build wind farms at the fastest rate possible - increasing capacity to 6,470 gigawatts, or more than two million onshore wind turbines at current spec - that would save about 12 gigatonnes of emissions a year through replacing coal, gas and oil-burning power plants.

Building nuclear reactors at the fastest rate possible, increasing from 460 plants today to 2,340 plants in 2050, could save about 8 gigatonnes a year by 2050, the calculator suggests.