I think this example presents the impact of our diet on our planet in a clear and convincing manner, thus I had to quote the text entirely| Ich denke, dass dieses Beispiel die Auswirkungen unserer Ernährung auf unseren Planeten in einer klaren und überzeugenden Art und Weise darstellt, deshalb musste ich den ganzen Text zitieren:

A hint of how food processing and packaging contribute to the energy and greenhouse gas budgets of the food system can be gleaned by the life-cycle analysis of a typical bottle of ketchup.

The Swedish Institute for Food and Biotechnology did a life-cycle analysis of tomato ketchup, to work out the energy efficiency and impacts, including the environmental effects of global warming, ozone depletion, acidification, eutrophication, photo-oxidant formation, human toxicity and ecotoxicity.

The product studied is one of the most common brands of tomato ketchup sold in Sweden, marketed in 1 kg red plastic bottles. Tomato is cultivated and processed into tomato paste in Italy, packaged and transported to Sweden with other ingredients to make tomato ketchup.

The aseptic bags used to package the tomato paste were produced in the Netherlands and transported to Italy; the bagged tomato paste was placed in steel barrels, and moved to Sweden. The five-layered red bottles were either made in the UK or Sweden with materials from Japan, Italy, Belgium, the USA and Denmark. The polypropylene screw cap of the bottle and plug were produced in Denmark and transported to Sweden. Additional low-density polyethylene shrink-film and corrugated cardboard were used to distribute the final product. Other ingredients such as sugar, vinegar, spices and salt were also imported. The bottled product was then shipped through the wholesale retail chain to shops, and bought by households, where it is stored refrigerated from one month to a year. The disposal of waste package, and the treatment of wastewater for the production of ketchup and sugar solution (from beet sugar) were also included in the accounting.

The accounting of the whole system was split up into six subsystems: agriculture, processing, packaging, transport, shopping and household.

There are still many things left out, so the accounting is nowhere near complete: the production of capital goods (machinery and building), the production of citric acid, the wholesale dealer, transport from wholesaler to the retailer, and the retailer. Likewise, for the plastic bottle, ingredients such as adhesive, ethylenevinylalcohol, pigment, labels, glue and ink were omitted.  For the household, leakage of refrigerants was left out. In agriculture, the assimilation of carbon dioxide by the crops was not taken into consideration, neither was leakage of nutrients and gas emissions such as ammonia and nitrous oxide from the fields. No account was taken of pesticides.

We estimated the energy use and carbon emissions for each of the six subsystems from the diagrams provided in the research paper, and have taken the energy content of tomato ketchup from another brand to present their data in another way (Tables 1 and 2), taking the minimum values of energy and emissions costs.

Table 1. Energy Accounting for 1 kg Tomato Ketchup
Subsystem Energy GJ

Agriculture 1.3
Processing 7.2
Packaging 7.8 (without waste incineration)
6.0 (with waste incineration)
Transport 1.0
Shopping 1.2
Household 1.4 (refrigeration for one month)
14.8 (refrigeration for one year)
Total (minimum) 18.1
Energy in 1 kg tomato paste 0.00432
Energy use per GJ tomato paste 4 190
Table 2. Carbon Dioxide Accounting for 1 kg Tomato Ketchup
Subsystem Carbon dioxide equivalent kg

Agriculture 190
Processing 500
Packaging 1 275 (without incineration)
2 315 (with incineration)
Transport 130
Shopping 195
Household 0
Total (minimum) 2 290

As can be seen, it takes at least 4190 units of energy to deliver 1 unit of ketchup energy to our dinner table, with at least 2 290 kg of carbon dioxide emissions per kg ketchup.

Packaging and food processing were the hotspots for many impacts. But at least part of the packaging is due to the necessity for long distance transport. Within the household, the length of time stored in the refrigerator was critical.

For eutrophication, the agricultural system is an obvious hotspot. For nitrous oxide emissions, transportation is another hotspot. For toxicity, the agriculture, food processing and packaging were hotspots, due to emissions of sulphur dioxide, nitrogen oxides and carbon monoxide; also heavy metals, phenol or crude oil. If leakage of pesticides, their intermediates and breakdown products had been considered, then agriculture would have been an even worse toxicological hotspot.

As regards the capital costs for tomato cultivation omitted from the study, literature from France gave a value of 0.180GJ/kg. As regards the wholesale and retail step left out of the study, literature data indicate 0.00143GJ/kg beer for storage at wholesale trader in Switzerland and 0.00166GJ/kg bread in the Netherlands.