Industrial development has drastically increased greenhouse gas emissions, and this issue will likely continue for a long period of time, further deteriorating the quality of air, soil, and water in the world and jeopardizing human life. Carbon dioxide (CO2), methane, and nitrogen oxide (NOx) are the primary greenhouse gas sources for global warming and climate change worldwide. Reducing these emissions is a global challenge and has been a major concern. Microorganisms (e.g., microalgae) can be an effective way of addressing some of these concerns. Nanomaterials can also offer structural features for reducing CO2 and other emissions in an environmentally friendly way. Combining microorganisms with nanomaterials can effectively capture greenhouse gases from the atmosphere and convert them to biofuels for transportation, industrial and household heating, and many other uses. In addition, plants naturally use CO2 emissions and other pollutants for their growth media. Even some biosystems can accumulate various substances in their bodies and reduce toxicity levels. As an outcome of this cycle, concentrations of specific pollutants in the air can be significantly reduced. Carbon dioxide contains an abundant source of carbon, which nurtures the growth of microbial species and plants in the environment, and can be biochemically transformed into renewable energy in order to meet the world's energy demand. This chapter summarizes the most recent developments in the field of CO2 emissions reduction, and applications of nanosystems and biological systems together to address some of the concerns of climate change and global warming.