From the beginning of the industrial revolution, anthropogenic activities have caused the concentration of atmospheric CO₂ to increase from about 270 parts per million (ppm) to over 370 ppm today. Current estimates suggest that atmospheric CO₂ concentration will reach 550 ppm by the year 2050 and over 700 ppm by the end of the 21st century. Preliminary data indicate that lipids are altered in response to CO₂. Lipid alterations in response to CO₂ may result directly from altered flux of carbon into lipid synthesis, some lipid alterations may be the result of gene expression changes, and some alterations in lipids may in themselves be regulatory. The objective of our work is to study the impact of elevated CO₂ level on the levels of phospholipids and galactolipids in Arabidopsis thaliana plants from varying locations and in a laboratory-selected genotype. Phospholipids and galactolipids from fifteen Arabidopsis thaliana genotypes grown at 380 ppm and at 700 ppm are being profiled by automated direct infusion electrospray triple quadrupole mass spectrometry. The data will be analyzed using multivariate techniques to determine the effects of CO₂ levels, on lipid molecular species, as well as on gene expression, phenotypic, and physiological data. Multivariate statistical analysis will also help establish relationships between lipid molecular species and the other measured parameters in order to better understand the biological processes underlying the adaptation of plants to elevated CO₂.