Climate change affects life on Earth. Meanwhile, microorganisms (unlike plants and animals) are usually not considered when studying climate change, particularly due to the impact of climatic fluctuation on them. A substantial variety of microbes and their responses to changing environmental conditions make determining their role in the ecosystem functioning very difficult. Nevertheless, microorganisms support the existence of all life forms on the planet. It is also important to know how microorganisms affect climate change and how this subsequently then affects microorganisms. Previous research demonstrates the leading role and importance of microorganisms in studying the biological aspects of climate change. Thus, this paper aimed to examine the correlation between nitrogen cycle microorganisms and climate change.

The nitrogen cycle microorganism (NCM) soil formed the primary research object, which, simultaneously, is not associative microflora and belongs to the following groups: amino heterotrophs using organic forms of nitrogen, aminoautotrophs using mineral forms of nitrogen, and diazotrophs fixing nitrogen in the air. The response of NCMs in simultaneously increasing atmospheric CO₂, precipitation, temperature, and nitrogen in an artificially created agricultural soil ecosystem was investigated.

The NCM number and their structure responded to these simulated changes. The increased volume of nitrogen significantly changed the NCM structure, which depends on temperature and precipitation. The dominance of NCMs was noted when the temperature and precipitation remained unchanged. However, the number of microorganisms consuming mineral forms of nitrogen increased following a rise in temperature and a reduction in precipitation. Further, the proportion of microorganisms consuming organic forms of nitrogen increased following a decrease in temperature and increased precipitation. Total NCMs reduced significantly when the CO2 increased; this decrease was most pronounced with increased precipitation. Changes in the group composition of the community are associated with an increase in the nitrification process, with no changes in total NCMs.

These results illustrate that the ever-increasing concentration of CO₂ in the atmosphere has a direct impact on both Earth’s climate and alters the composition and activity of microbial populations.