Climate change is a global problem that requires a global solution. The UN is leading efforts to provide a scientific assessment of the consequences of this problem and to promote its policy decision. The Intergovernmental Panel on Climate Change, which brings together 2000 leading scientists dealing with climate change issues, publishes comprehensive scientific assessments every five to six years: in 2007, it made the final conclusion that climate change is a real fact and that one of its main causes is human activity. Currently, 196 participants in the United Nations Framework Convention on Climate Change are negotiating to conclude agreements to reduce air emissions that contribute to climate change, which will help countries deal with the consequences. The United Nations Environment Program (UNEP) and other agencies of the UN system play a leading role in informing the public about this problem.The UN provides assistance to developing countries in addressing the challenges posed by global climate change. Thirty-eight UN agencies have created a partnership to find a comprehensive solution to this problem. For example, the Global Environment Facility, uniting 39 UN agencies, finances projects in developing countries. As a financial mechanism for the Climate Convention, it provides about $ 550 million per year for projects aimed at finding new technologies, improving energy efficiency, finding renewable energy sources and creating sustainable transport systems.The UN is addressing global environmental problems. As an international forum for consensus building and negotiating agreements, the UN is addressing global issues such as climate change, ozone depletion, toxic waste, deforestation and the extinction of species, as well as air and water pollution. Until these problems are resolved, it will not be possible to ensure the long-term stability of markets and economic economies, as environmental losses lead to depletion of natural “capital”, which provides the basis for economic growth and the very existence of mankind.The United Nations Environment Program and the World Meteorological Organization play an important role in determining the extent of damage to the ozone layer of the Earth. The implementation of the provisions of the treaty, known as the Montreal Protocol, has allowed countries to phase out chemicals that cause depletion of the ozone layer and replace them with safe substances. This will help to save millions of people from a disease such as skin cancer, which is a consequence of increased ultraviolet radiation.During the International Decade for the Supply of Drinking Water and Sanitation (1981-1990), more than a billion people for the first time in their lives gained access to safe drinking water. By 2002, another 1.1 billion people had access to safe drinking water. The 2003 International Year of Freshwater helped to understand more clearly the importance of preserving this valuable resource. During the International Decade for Action, “Water for Life” (2005-2015), it is envisaged to halve the proportion of people without access to safe drinking water.About 90% of the large marine fish stocks are exploited almost to the point of their stable limits or even beyond this side. FAO monitors global fisheries and the status of wild fish stocks and works with countries to improve fisheries management, eradicate illegal fishing, encourage responsible international fish trade and protect endangered species and the environment.In order to rid the world of ever-created most dangerous chemicals, the Stockholm Convention on Persistent Organic Pollutants was adopted. This Convention, ratified by 179 countries, is aimed at banning the use of 23 hazardous pesticides and industrial chemicals that can lead to death, damage to their nervous and immune systems, cause cancer and reproductive harm and interfere with the normal development of children. Other UN conventions and action plans help preserve biodiversity, protect endangered species, combat desertification, cleanse the seas and limit the transboundary movement of hazardous waste.