We propose in this interdisciplinary session to present results from meta-analytical studies on the effects of environmental changes on ecological systems. Examples will be drawn from diverse areas of research, including elevated CO2, elevated O3 and increased nitrogen deposition, on microbes and plants at different organizational levels. The first goal of this session is to showcase our latest understanding of how environmental perturbations will affect various ecosystems. A better understanding of what will happen in a future environment is essential to help restore ecosystems before human dominance. The second goal is to critically examine the role of meta-analysis in synthesizing results from empirical studies that differ in species, duration and organizational levels. A number of ecologists with different expertise and at different stages of their careers will be speaking at this session. The speakers will present new findings on a wide range of topics with the focus being changes in ecosystems brought about by global environmental changes. We will adopt the format of introduction-presentations-discussions. After a brief introduction, we will take on the values of meta-analysis as a compliment to the one-at-a-time tests of statistical hypotheses, then an elaboration of the role that meta-analysis can play in ecology in the 21st century, and the effects of environmental changes on primary productivity of grasslands, forest ecosystems, crop production, and belowground processes. Talks on different aspects of ecosystems in a changing world will be complementary to one another. Dr. Gurevitch, who first introduced meta-analysis into ecology in the early 1990s, will speak on where meta-analysis stands and where it is heading as a tool for synthesizing ecological studies. The closing 30 minutes of the session will encourage discussion among speakers and the audience, providing a venue for examining the pros and cons of meta-analysis relative to one-at-a-time empirical studies.