In 2016, a United Nations Environment Programme (UNEP) Frontiers report identified a series of global and emerging environmental problems that bring new challenges for the national and international envronmental agencies and sustainable development organizations. In the last 50 yearts scientific research detailed monitoring and statistical records on a global scale prioritised environmental problems for their significance and the need for urgent action. These studies created greater awareness of the environmental problems and the urgent need to take remedial action. For example, urban air photochemical pollution from vehicular exhausts, the stratospheric ozone layer depletion in Antarctica, water pollution by agricultural runoffs and microplastics, soil erosion and desertification, industrial and municipal toxic sewage wastewater, ,damaging acid rain events in the lakes of Scandinavian countries, excessive population growth and urbanization in most continents, deforestation of vast areas of valuable tropical forests loss of biodiversity, climate change, were some examples that threatened natural resources, human health and sensitive ecosystems. But although some of these environmental problems attracted new and strict regulations, restriction of emissions, banning certain toxic and carcinogenic chemicals (microplastics, pharmaceutical and pesticide residues, etc), introduction of green chemistry processes and restriction of certain wasteful practices in indutrial and agricultural sectors, novel emerging environmental problems appeared in the 21st century on a global scale that need new sustainable changes and the introduction of renewable energy sources and reduced use by mankind of non-renewable resources. At the same time old problems like overpopulation, urbanization, energy and food consumption trends, limits to continued unsustainable economic growth of developing countries need to be taken into account. The UN Environment’s Sixth Global Environmental Outlook (GEO-6) in 2019 is the latest most comprehensive assessment of the state of the world’s environment and emerging environmental problems. The report also offers a rigorous analysis of Earth’s sustainable prospects and the most important environmental issues facing the Earth in the next decades. This review collected some important reports and scientific papers on the emerging environmental problems that will feature prominently in the future.