Elevated CO₂ Concentration in Iwate Prefecture, Minamitori-jima Island, and Yonaguni Island - Global Extreme Weather and Observation Network Alarm Bells (1998)

Elevated CO₂ Concentration in Iwate Prefecture, Minamitori-jima Island, and Yonaguni Island - Global Extreme Weather and Observation Network Alarm Bells (1998)

In the late 1990s, data supporting the scientific evidence of global warming began to be reported in various regions. In particular, the 1997-98 El Niño phenomenon occurred on a record scale, causing a worldwide rise in temperature and changes in precipitation patterns. The rapid increase in CO₂ concentrations captured by the Japan Meteorological Agency's observation network during this period was an alarming sign of the fragility of the climate system.

According to observations at Ayari (Iwate Prefecture), Minamitorishima (Ogasawara Islands, Tokyo), and Yonaguni Island (Okinawa Prefecture), CO₂ concentrations in the atmosphere increased by 28 to 31 ppm in just one year. Considering that the normal annual increase is around 2ppm, this is an extraordinary rapid increase. This is believed to be the result of El Niño, which caused temperatures in the tropics to rise, accelerating the decomposition of organic matter in the soil and releasing large amounts of CO₂. It was also pointed out that increased forest fires and vegetation changes may have also contributed to the increase.

At the time, the international community was just beginning to discuss the Kyoto Protocol of 1997, which imposed an obligation on developed countries to reduce greenhouse gas emissions, and the results of this observation attracted much attention as evidence of the urgency of this issue. Japan's observation network had the advantage of being able to grasp changes in the global carbon cycle by taking advantage of its geographical characteristics, extending from east to west, north to south. Ayazato reflected the background atmosphere of the northwest Pacific, Minamitori Island reflected the influence of the equatorial region, and Yonaguni Island reflected transport from the East Asian continent, each providing important data on trends in different climatospheres.

This observation demonstrated that the progression of global warming is not merely a long-term trend, but can be rapidly accelerated by El Niño and other climate change factors. 1998's extraordinary increase in CO₂ concentrations reminded not only scientists but also policy makers and the general public that "the climate system is unstable and, if left unchecked, could be irreversible. The extreme rise in CO