In the midst of the current international debate on global warming, it is instructive to note that it has taken the United Nations and the international community some two generations to reach this point.

To fully understand the current debate, one must look at the rise in prominence of environmental issues on the global agenda and the evolution of climate change within that context. Environmental issues, much less climate change, were not a major concern of the United Nations in the period following the Organization's creation. During its first 23 years, action on these issues was limited to operational activities, mainly through the World Meteorological Organization (WMO), and when attention was paid to them, it was within the context of one of the major preoccupations of that time: the adequacy of known natural resources to provide for the economic development of a large number of UN members or the "underdeveloped countries", as they were then termed.

In 1949, the UN Scientific Conference on the conservation and utilization of resources (Lake Success, New York, 17 August to 6 September) was the first UN body to address the depletion of those resources and their use. The focus, however, was mainly on how to manage them for economic and social development, and not from a conservation perspective. It was not until 1968 that environmental issues received serious attention by any major UN organs. The Economic and Social Council on 29 May was the first to include those issues in its agenda as a specific item and decided-later endorsed by the General Assembly-to hold the first United Nations Conference on the Human Environment.

Held in Stockholm, Sweden from 5 to 16 June 1972, the UN Scientific Conference, also known as the First Earth Summit, adopted a declaration that set out principles for the preservation and enhancement of the human environment, and an action plan containing recommendations for international environmental action. In a section on the identification and control of pollutants of broad international significance, the Declaration raised the issue of climate change for the first time, warning Governments to be mindful of activities that could lead to climate change and evaluate the likelihood and magnitude of climatic effects.

The UN Scientific Conference also proposed the establishment of stations to monitor long-term trends in the atmospheric constituents and properties, which might cause meteorological properties, including climatic changes. Those programmes were to be coordinated by WMO to help the world community to better understand the atmosphere and the causes of climatic changes, whether natural or the result of man's activities. The Conference also called for the convening of a second meeting on the environment and established the Governing Council of the United Nations Environment Programme (UNEP), with its secretariat in Nairobi, Kenya, the Environment Fund and the Environment Coordination Board. But climate change did not become a central preoccupation of those bodies. Water resources, marine mammals, renewable energy resources, desertification, forests, environmental legal framework and the issue of environment and development took centre stage.

Over the next 20 years, as part of efforts to implement the 1972 decisions, concern for the atmosphere and global climate slowly gained international attention and action. In 1979, the UNEP Governing Council asked its Executive Director, under the Earth Watch programme, to monitor and evaluate the long-range transport of air pollutants, and the first international instrument on climate-the Convention on Long-Range Transboundary Air Pollution-was then adopted. UNEP took it to another level in 1980, when its Governing Council expressed concern at the damage to the ozone layer and recommended measures to limit the production and use of chlorofluorocarbons F-11and F-12. This led to the negotiation and adoption in 1985 of the Vienna Convention for the Protection of the Ozone Layer and the conclusion of a Protocol to the 1979 Transboundary Air Pollution Convention, which aimed at reducing sulphur emissions by 30 per cent. In the meantime, palpable evidence of climate change due to air pollution was beginning to emerge in the phenomena of acid rain in Europe and North America, which resulted in various programmes by UNEP and WMO for keeping it in check.

However, in 1987 the UN General Assembly gave real impetus to environmental issues, when it adopted the Environmental Perspective to the Year 2000 and Beyond-a framework to guide national action and international cooperation on policies and programmes aimed at achieving environmentally sound development. The Perspective underlined the relationship between environment and development and for the first time introduced the notion of sustainable development. It was disappointing, however, that such a long-term policy document, while recognizing the need for clean air technologies and to control air pollution, did not make climate change a central issue, but subsumed it under its policy directive related to energy.

In 1988, global warming and the depletion of the ozone layer became increasingly prominent in the international public debate and political agenda. UNEP organized an internal seminar in January to identify environmental sectors that might be sensitive to climate change. The Intergovernmental Panel on Climate Change (IPCC), a forum for the examination of greenhouse warming and global climate change, was established and met for the first time in November. The General Assembly identified climate change as a specific and urgent issue. In its resolution on the protection of global climate for present and future generations of mankind, it asked WMO and UNEP to initiate a comprehensive review and make recommendations on climate change, including possible response strategies to delay, limit or mitigate the impact of climate change. As a result, 1989 was a watershed year for climate change, as the first significant global efforts were taken. The Assembly, in resolution 44/207, endorsed the UNEP Governing Council's request to begin preparations with WMO for negotiations on a framework convention on climate change; regional action was also being taken. In addition, the Maldives transmitted the text of the Malé Declaration on Global Warming and Sea Level Rise to the UN Secretary-General and the Helsinki Declaration on the Protection of the Ozone Layer was adopted on 2 May. Also in 1989, the Montreal Protocol on Substances that Deplete the Ozone Layer entered into force.

Efforts to raise awareness of the effects of climate changes were further advanced at the second World Climate Conference, held from 29 October to 7 November 1990. In its Ministerial Declaration, the Conference stated that climate change was a global problem of unique character for which a global response was required. It called for negotiations to begin on a framework convention without further delay. As the urgency for a stronger international action on the environment, including climate change, gained momentum, the General Assembly decided to convene in 1992 in Rio de Janeiro, Brazil, the United Nations Conference on Environment and Development. The Earth Summit, as it is also known, set a new framework for seeking international agreements to protect the integrity of the global environment in its Rio Declaration and Agenda 21, which reflected a global consensus on development and environmental cooperation. Chapter 9 of Agenda 21 dealt with the protection of the atmosphere, establishing the link between science, sustainable development, energy development and consumption, transportation, industrial development, stratospheric ozone depletion and transboundary atmospheric pollution.

The most significant event during the Conference was the opening for signature of the United Nations Framework Convention on Climate Change (UNFCCC); by the end of 1992, 158 States had signed it. As the most important international action thus far on climate change, the Convention was to stabilize atmospheric concentrations of "greenhouse gases" at a level that would prevent dangerous anthropogenic interference with the climate system. It entered into force in 1994, and in March 1995, the first Conference of the Parties to the Convention adopted the Berlin Mandate, launching talks on a protocol or other legal instrument containing stronger commitments for developed countries and those in transition.

The cornerstone of the climate change action was, therefore, the adoption in Japan in December 1997 of the Kyoto Protocol to the UNFCCC, the most influential climate change action so far taken. It aimed to reduce the industrialized countries' overall emissions of carbon dioxide and other greenhouse gases by at least 5 per cent below the 1990 levels in the commitment period of 2008 to 2012. The Protocol, which opened for signature in March 1998, came into force on 16 February 2005, seven years after it was negotiated by over 160 nations.

Once again, the United Nations has shown its leadership role in bringing issues requiring global action to international attention. However, its efforts throughout the years to make the issue of climate change a central focus of the international agenda continues, even as opposing sides of the debate try to make their case. As evidence of the risks of ignoring climate change become more striking, the United Nations will persevere in that effort until the issue is embraced by all.