One of our recent major themes is plant responses to increases in atmospheric CO2 concentration, global warming and other environmental changes. CO2 spring is one of unique system to study long-term response of plants to elevated CO2, because plants might have exposed to elevated CO2 over generations. We have found that plants inhabiting in high CO2 area around the springs have different traits from plants inhabiting normal CO2 area. This suggests that elevated CO2 promotes plant microevoution. Such evolutionary changes in plant traits may happen in a future high-CO2 world. The photograph shows the measuring of the photosynthesis rate around a CO2 spring, which emitts volcanic gasses that contains high concentration of CO2. Arround the spring, the ecosystem is exposed to high CO2 concentration. The plant treated in the photograph had been exposed to approximately 2,800 ppm CO2, roughly seven times the normal amount in the atmosphere.