A commuter uses the Climate Card introduced by the Seoul Metropolitan Government at City Hall Station on lines 1 and 2, Jan. 29. Korea Times photo by Shim Hyun-chul

The Climate Card, Seoul's new unlimited transit pass, is facing a supply shortage due to soaring demand, according to the Seoul Metropolitan Government, Friday. Launched on Jan. 23, the card provides access to all bus routes, subway lines and the city's bike-sharing service known as Ttareungyi, for a monthly fee of 65,000 won ($49).

According to the city government, approximately 310,000 Climate Cards — 124,000 mobile cards and 191,000 physical cards — have been sold in about a week since the launch of the service Jan. 27.

Despite the city government producing a total of 200,000 physical cards, including 100,000 spares, they are running short due to the high demand.

In a swift response to the overwhelming demand, the city government has begun to produce an additional 150,000 physical cards and aims to increase the card supply. The extra inventory is expected to be available for commuters starting March 7.

The scarcity of physical cards is particularly noticeable at subway stations on Seoul Metro Line 2, primarily used by many office workers and students.

Seolleung Station, Hongik University Station, Sillim Station and Samseong Station on Line 2 and Kkachisan Station on lines 2 and 5 have seen the highest sales of physical cards.

The surge in demand for physical cards seems to be attributed to the exclusive compatibility of mobile cards with Android phones. While Android users can use the unlimited transit pass by simply downloading the Tmoney app and transferring the monthly fee, iPhone users must purchase a physical card as Apple smartphones are not compatible with device and card scanning systems use for local public transport.

As securing a physical Climate Card has become challenging, customer safety centers in subway stations, where commuters can purchase physical cards, have been recently posting signs notifying of the dwindling stocks.

Some commuters are even resorting to online platforms for used-item transactions, where physical cards priced originally at 3,000 won are being sold at inflated prices.

However, transferring and selling physical cards is prohibited, according to the relevant law, so there are growing calls for regulations.

Complaints about the use of physical cards are also growing, as they can only be charged with cash.

Responding to citizen requests, Seoul Mayor Oh Se-hoon announced plans to introduce a credit card payment system for physical cards in April, aiming to alleviate the inconvenience of relying solely on cash for recharging.