There are hidden costs to eating meat not included in the price tag.

If consumers in the western world were also charged for the greenhouse gas impacts of their hearty meal of protein, a new study estimates they would have to pay nearly 2.5 times – or 146 percent more – than today.

If the meat is organic, that carbon cost surcharge would amount to 70 percent.

"These external costs are not yet included in the market prices for food and, in the absence of current compensation payments, lead to significant market price distortions and welfare losses for society as a whole," the authors write.

This is what neoclassical economists call a market failure. It's what happens when private financial decisions fail to account for general welfare. In this case, neither the buyer nor the seller is taking on the environmental burdens of the product. Instead, disaster of unknown price is being passed on to the planet and human society at large.

Last year, a global estimate found the hidden cost of food to be roughly US$12 trillion a year, and by 2050, that could rise to $16 trillion (about the gross domestic product of the entire country of China).

"What is equally alarming is that these costs are not being regularly counted, and the food and agriculture industries seem to assume that the bill will be paid," reads a Nature editorial on last year's report.

"That isn't right and has to change."

If we don't balance the true costs and benefits of meat products, experts warn that others in the market, future generations and the natural environment, will continue to pay for the difference.

Better regulation, food taxes, and fines for carbon polluters might be a good way to reduce demand and to compensate for damage, but calculating the true cost of our emissions and their social and environmental impacts is extremely difficult in a rapidly changing world.

Few studies to date have compared the hidden costs among different types of food and the ways they are farmed.

With this in mind, researchers in Germany have now quantified and monetised the emissions from various meats and plant-based foods grown organically or conventionally.

Tracing the entire lifecycle of the product, from production to usage to disposal, the team found it was the category of food that had a larger impact on emissions. How it was farmed mattered less, although the difference was still significant, depending on the product.

External climate costs, not included in the price tag, were highest for both conventional and organic animal-based products, and especially so for meat.

Dairy was only slightly better. Estimates show that conventional animal products like milk and eggs should cost nearly double what they currently do.

On the other hand, plant-based products were the least carbon-polluting food of them all, especially organic fruits and vegetables, which the authors say should only cost 6 percent more than they do today.

"The large difference of relative external climate costs between food categories as well as the absolute external climate costs of the agricultural sector imply the urgency for policy measures that close the gap between current market prices and the true costs of food," the authors argue.

Too much meat

Today, agriculture is a primary contributor to the emissions that are accelerating climate change; that's especially true for the production of livestock, which occupies more than a fourth of all land on this planet. Merely feeding these animals takes up a third of arable soil.

Growing evidence suggests cutting down on our total meat consumption may be an important way to reduce our global greenhouse gas emissions, yet meat production in the next few decades is only expected to increase.

Even if all future meat products were farmed organically, it likely wouldn't make a big enough difference. The direct emissions from the animal, its food, the soil, and its fertiliser will likely still produce negative external costs to the environment and, in turn, human society.

For instance, the new estimate found pork was the only category of meat that produced fewer emissions when grown organically. Yet because it makes up such a big part of meat production globally, it lowered the overall carbon-cost surcharge the researchers calculated for organic meats.

There are probably several reasons why organic meat produces similar emissions to more conventionally produced meat. Organic livestock farming tends to involve more land per animal, and these animals also tend to live longer and yield less product, for example.

However, the authors argue that shifting to organic practices might be beneficial depending on the region, and this 'yield gap' would decrease over time, along with increased benefits for soil quality that arise from organic practices.

"Although organic products are not always associated with lower emissions than conventional products (in the case of eggs, poultry, and ruminants), percentage price increases of organic products are consistently lower than for conventional products," the researchers write.

"Correspondingly, decreases in demand are lower for organic products. Thus, there would be a consistent advantage for organic products along with all products categories."

Overall, if the external costs of meat are internalised by producers and consumers, it could strengthen sustainable behaviour and help mitigate climate change; consumers opting for "environmentally detrimental" foods would be directly paying for the damage they cause.

If that meant people ultimately bought fewer animal products because they were more expensive, that could free up an enormous amount of land. It could also reduce the vast amount of food waste the world currently produces, the paper suggests, because "appreciation for food would rise with its increased monetary value."

For meat-lovers, a price increase on your meal might not sound very appetising, but as the authors note, individual consumers are already paying for the environmental costs of agriculture, they're just doing so indirectly – through things like emergency aid for extreme weather conditions.

While the new model was used to compare the external costs of food and its impact on climate change in Germany specifically, the authors say their method can be applied to much more than meat, allowing us to calculate a whole host of environmental costs the world over and implement ways in which to pay for them.

We can't afford to wait any longer.

The study was published in Nature Communications.