Photosynthesis is of critical importance to biodiversity, food security and society within the context of current climate change. The photosynthetic responses of plants to rising atmospheric CO2 have been studied in experiments where CO2 is artificially enriched to predicted levels. However, these experiments involve plants adapted to current “low” ambient levels of ~380ppm CO2, and do not incorporate consideration of plant evolutionary adaptation of photosynthesis, where the physiology of plants adjust to long-term incremental CO2 rises. Plants growing around volcanic CO2 degassing vents possess an evolutionary adaptation to “high” atmospheric CO2 and display markedly different responses than plants adapted to lower ambient CO2. Plants adapted to “high” CO2 exhibit pronounced photosynthetic rates, no down-regulation of photosynthetic physiology and maintenance of transpiration rates – all important parameters for coupled atmosphere-biosphere models of climate, vegetation and carbon sequestration responses to aid management and mitigation of future climate change. These evolutionary responses to CO2 are also present in the plant fossil record over timescales of millions of years. The stomata of fossil plants are used to reconstruct past atmospheric levels of CO2 in the study of previous global-warming events that provide important climate/biodiversity indicators for the current global-warming crisis. The use of living plants adapted to both “high” and “low” atmospheric CO2, in comparative physiology/morphology studies under elevated CO2, will provide much needed data on likely plant responses to rising CO2 and those of plant fossils through earth history. This will place Europe at the forefront of plant evolution and palaeoclimatic research; linking two European research institutions (IBIMET, Italy and UCD, Ireland) in the European Research Area to create a platform for European Research Excellence and competitiveness.