Economic shifts do not always start in statistics. Warning signs—soaring produce prices, blocked logistics, stalled factory floors—often surface in the field before they appear in official data. Satellite imagery is the broadest lens for capturing these changes. ChosunBiz, together with space AI solutions corporations TelePIX, cross-analyzes satellite imagery and economic data to trace where key economic issues begin and how they ripple through markets, and to diagnose on-the-ground changes that conventional statistics can miss. [Editor's note]
In Sep. 2024, after the Chuseok holiday, cabbage priced at 20,000 won per head appeared in markets. The average retail price tallied by the Korea Agro-Fisheries & Food Trade Corporation (aT) neared 10,000 won, and wholesale prices—which reflect conditions at the source first—jumped to about twice the normal year's level. Cabbage, a staple on the table, turned into "gold cabbage" in a matter of days.
The starting point of the cabbage price surge is the highland fields of Gangwon, where cabbage grows even in midsummer. High-altitude areas over 600 meters above sea level, such as Taebaek, Jeongseon, and Pyeongchang, stay relatively cool even in July–August, when lowland cabbage fields weaken in the heat. After spring cabbage shipments end and before autumn kimchi cabbage arrives, highland cabbage (summer cabbage) from here fills the gap in domestic supply.
But when yields at the source worsen or cultivation area shrinks, the shortage is reflected in prices right away. Demand for cabbage does not easily drop because it is hard to leave it out of kimchi, restaurant side dishes, and meal service ingredients.
So can we check before harvest whether cabbage prices will rise or fall? We looked for that possibility in satellite imagery of Gangwon's main highland cabbage-growing areas. Satellites can repeatedly observe vegetation changes across wide regions without inspecting fields one by one. They record data showing whether the planted area has decreased, whether growth conditions differ from past years, and how vegetation signals change at specific times.
◇ The difference between bumper and poor harvests showed up in satellite vegetation indices
This analysis used Sentinel-2 satellite imagery operated by the European Space Agency (ESA). Sentinel-2 observes the surface at roughly 10-meter resolution and repeatedly images the same area at multi-day intervals.
A cabbage field in Bangnim-myeon, Pyeongchang County, Gangwon, looked markedly different in satellite imagery from 2019 and 2024. In 2019, a bumper year, relatively even vegetation signals appeared across the field. In 2024, a poor year, more areas showed weak or uneven growth.
Satellites read plant growth conditions by the way light is reflected. Healthy, growing plants strongly reflect certain wavelengths, and satellites use this information to calculate numerical values.
A representative metric is the normalized difference vegetation index (NDVI). NDVI is a vegetation index showing how actively plants are growing; the higher the value, the more vigorous the growth. Based on this, we also tracked how the vegetation index changes along the growth rhythm in which cabbage is planted in June, grows rapidly in July–August, and enters heading (the phase when the head fills) in early September.
Annual analyses of Gangwon's highland cabbage belt showed that the cabbage field area captured by satellites closely matched actual output. The correlation coefficient between satellite-detected area and Gangwon highland cabbage production from 2019 to 2024 was +0.91. The correlation coefficient indicates how closely two indicators move together. The closer to +1, the stronger the tendency for one to increase when the other increases.
◇ Changes in cabbage field area also aligned with price trends
The cabbage field area estimated by satellite was also linked to market prices. Compared with September wholesale prices at Garak Market, prices were low in 2021, when the satellite-detected area was large, and high in 2024, when the area was small.
According to the Ministry of Data and Statistics (MODS) Korean Statistical Information Service (KOSIS), actual Gangwon highland cabbage production fell from about 227,000 tons in 2017 to 149,000 tons in 2024, a 34.8% decrease over eight years. During the same period, cultivation area shrank 26.4%, from 4,733 hectares to 3,483 hectares.
In 2021, when production was highest, the annual average wholesale price of cabbage was 809 won per kilogram, but in 2024, when production was lowest, it reached 1,775 won per kilogram—about double. From 2017 to 2024, the correlation coefficient between Gangwon highland cabbage output and wholesale prices was -0.88, indicating a strong relationship in which prices rose in years when production fell.
The biggest driver of lower production was reduced cultivation area. From 2017 to 2024, about 72% of the production decline was explained by a decrease in area. The remaining 28% was due to lower yield per unit area. The correlation coefficient between cultivated area and production was a very high +0.97.
However, MODS figures show that Gangwon highland cabbage cultivation area in 2023 was 3,774 hectares, down from 4,069 hectares in 2022, with output also decreasing. Yet satellite analysis detected a larger cabbage field area in 2023 than in 2022.
Price trends were closer to the satellite analysis. Looking at September wholesale prices at Garak Market, cabbage prices fell sharply from 3,349 won per kilogram in 2022 to 1,957 won per kilogram in 2023. This shows satellite imagery can serve as a supplementary resource to interpret price movements alongside after-the-fact statistics.
◇ Hotter summers make early observation more important
Climate change is behind the shrinking highland cabbage fields. Cabbage grows well in cool climates. As summer temperatures rise, areas suitable for cultivation shrink, and the risks of pests, disease, and poor growth increase.
Data from 2017 to 2024 shows that in years with higher average temperatures during the growing season (June–September), both cultivated area and yield per unit were lower. During the 2024 growing season for Gangwon highland cabbage, the average temperature was 21.4 degrees, the highest in the analysis period, while cultivated area was 3,483 hectares and yield was 4,264 kilograms per 10 ares (are; 1 are is 100 square meters), both the lowest levels in eight years.
The long-term outlook is not good if fossil fuel use continues. According to forecasts by the Rural Development Administration, under a warming scenario, areas suitable for growing highland cabbage could shrink drastically. The currently suitable cultivation area of about 14,800 hectares is projected to fall to 1,261 hectares in the 2030s, down 91% from today. One projection suggests it could drop to 44 hectares in the 2060s, a 99.7% decrease from today.
Highland cabbage prices start to move in earnest after volumes are shipped to wholesale markets. Before that, changes in cultivation area and growth conditions unfold at the source. As climate change destabilizes conditions for growing highland cabbage, the need for data that repeatedly observes changes in producing areas is expected to grow.