- François-Xavier Branthôme
Ketchup and other tomato products, stalwarts of many meals, may soon be a much rarer commodity as climate change threatens to halve the fruit’s global harvest this century, according to a new study. In the worst-case scenario, between 2050 and 2100, the tomato harvest could be halved.
Soaring temperatures mean the plants, like most crops worldwide, are being increasingly put under stress. The bulk of the global production of processing tomatoes is concentrated in a small number of regions where climate change is projected to have a significant impact on the future production and supply to the tomato processing industry.
In a recent study published on Nature Food, coordinate by Professor Domenico Ronga at University of Salerno and Professor Davide Cammarano at Arhus University, and conducted in collaboration with colleagues of Purdue University (Sajad Jamshidi), University of Texas (Dev Niyogi), University of Florida (Gerrit Hoogenboom), and NASA Goddard Institute for Space Studies (Alex C. Ruane), the authors predict vast changes in the tomato industry due to the climate change induced rise in temperature in the future.
Last year, the Intergovernmental Panel on Climate Change (IPCC) outlined five future global warming scenarios covering different levels of fossil fuel use and emissions.
Different projected climate scenarios were used in the study, but all pointed to a future where tomato production will change dramatically within the next 30-40 years.
Overall, the research found that by 2050, compared with the baseline period of 1980-2009, there would be around a six per cent decline in tomato production in the three countries, due to the projected increase in air temperature, with little difference between the five potential futures. But between 2050 and 2100, there is a stark difference depending on the climate model used and in the worst-case scenario, the tomato harvest could be halved.
“The production of the three main tomato-producing countries (Italy, China, the USA, which together account for 65 per cent of global production) is halved by 2100 under the worst case scenario,” Dr. Cammarano said.
The worst-case scenario would involve a temperature increase in the tomato-producing regions of about 2.6°C between 2040 and 2069, and 5°C for 2070–2099, when compared to the baseline period of between 1980 and 2009.
Under these stipulations, the computer model projected that the global harvest of processing tomatoes in the 11 biggest growers would drop from the current 14 million tonnes a year level to less than seven million tonnes.
Processing tomato is grown in many different parts of the world, but three countries dominate the productions of processing tomatoes (California, Italy and China) counting for more than 65% of the global production.
Warmer temperatures reduce yield
If the temperature increases as the study projections shows, California and Italy might not be able to sustain current levels of processing tomato production due to too high temperature as well as water resource constraints.
Dr Davide Cammarano, the lead author of the study from Aarhus University, explained: “The threat of climate change is significant, especially because the type of tomato we dealt with in this study (processing tomatoes that are field grown and mechanically harvested) requires irrigation.
“It is likely that more water will be needed to keep a profitable production in the future. This has important implications because water is something that is going to be less available for agriculture in some of the areas considered in this study.”
Warmer temperatures speed up how quickly plants grow, resulting in a shorter time for fruit development and therefore reducing yield.
“All crops have an optimal temperature during which development is optimal,” the scientists write. “However, above this threshold temperature there is an acceleration in the senescence processes that has a negative impact on yield.
“The future viability of processing tomato production is different for each region,” they add. Cooler regions such as China and the northern parts of California actually seem to benefit from the rise in temperature and might in fact gain a competitive advantage.
“China will be one of the regions that is projected to be able to maintain a viable production of processing tomatoes… [but] California and Italy will be negatively impacted by the projected environmental changes.”
According to the projections of this study climate change poses as a big problem for the tomato processing industry, within the next 30 years Italy as an example will not be able to produce tomatoes any longer.
This causes a problem in the supply chain for the industry, they will need to get tomatoes from other regions. Logistically this causes a problem, but it is also rather costly both in terms of economy and most certainly also in terms of CO2 emitted during transportation.
Dr. Cammarano added: “The study shows that even lower levels of warming are enough to alter the major suitability zones for tomato production.
“Adaptation to climate changes can increase production, and this study emphasizes the need to consider future climate shifts in designing resilient tomato production and value chains.”
Cammarano, D., Jamshidi, S., Hoogenboom, G. et al. Processing tomato production is expected to decrease by 2050 due to the projected increase in temperature. Nat Food 3, 437–444 (2022)
Sources: Domenico Ronga, telegraph.co.uk, phys.org, ndtv.com, groundreport.in, futurity.org, technologynetworks.com, slurrp.com