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Greenhouse gases and climate change

Carbon dioxide concentrations at Mauna Loa, Hawaii (parts per million by volume)

Records from Mauna Loa, Hawaii, show how CO2 concentrations have increased - the increase is largely due to anthropogenic emissions that result from burning fossil fuel

Source: Keeling and Whorf 2001

Scientists have known about the natural 'greenhouse effect' for more than a century (Arrhenius 1896): the Earth maintains its equilibrium temperature through a delicate balance between the incoming solar energy (short wavelength radiation) it absorbs and the outgoing infra-red energy (long wavelength radiation) that it emits and some of which escapes into space. Greenhouse gases (water vapour, carbon dioxide, methane and others) allow solar radiation to pass through the Earth's atmosphere almost unimpeded but they absorb the infra-red radiation from the Earth's surface and then re-radiate some of it back to the Earth. This natural greenhouse effect keeps the surface temperature about 33C warmer than it would otherwise be - warm enough to sustain life.

Since the industrial revolution, the concentration of CO2, one of the major greenhouse gases, in the atmosphere has increased significantly (see graph, which reflects growth since direct measurements started in 1957). This has contributed to the enhanced greenhouse effect known as 'global warming'.

The CO2 concentration in the atmosphere is currently about 370 parts per million (ppm) - an increase of more than 30 per cent since 1750. The increase is largely due to anthropogenic emissions of CO2 from fossil fuel combustion and to a lesser extent land-use change, cement production and biomass combustion (IPCC 2001a). Although CO2 accounts for more than 60 per cent of the additional greenhouse effect accumulated since industrialization, the concentrations of other greenhouse gases such as methane (CH4), nitrous oxide (N2O), halocarbons and halons have also increased. In comparison to CO2, CH4 and N2O have contributed about 20 per cent and 6-7 per cent respectively to the additional greenhouse effect. Halocarbons have contributed about 14 per cent. Many of these chemicals are regulated under the Montreal Protocol (see above). However, those which have negligible ozone-depleting potential are not controlled under the Montreal Protocol. Although they have accounted for less than 1 per cent of the additional greenhouse effect since industrialization, their concentrations in the atmosphere are increasing (IPCC 2001a).

Greenhouse gas emissions are unevenly distributed between countries and regions. In general, industrialized countries are responsible for the majority of historical and current emissions. OECD countries contributed more than half of CO2 emissions in 1998, with an average per capita emission of about three times the world average. However the OECD's share of global CO2 emissions has decreased by 11 per cent since 1973 (IEA 2000).

In assessing the possible impact of rising atmospheric concentrations of greenhouse gases, IPCC concluded in 2001 that 'there is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities'. The overall warming amounts to about 0.6 (0.2)C over the 20th century; the 1990s are 'very likely' to have been the warmest decade and the year 1998 the warmest year in the instrumental record, since 1861. Much of the rise in sea level over the past 100 years (about 10 to 20 cm) has probably been related to the concurrent rise in the global temperature (IPCC 2001a).

Ecosystems, human health and economy are all sensitive to changes in climate - including both the magnitude and rate of climate change. Whereas many regions are likely to experience adverse effects of climate change - some of which are potentially irreversible - some effects could be beneficial for some regions. Climate change represents an important additional stress on those ecosystems already affected by increasing resource demands, unsustainable management practices and pollution.

Some of the first results of the changing climate can serve as indicators. Several vulnerable ecosystems such as coral reefs are seriously endangered by increased sea temperature (IPCC 2001b) and some populations of migratory birds have been declining because of unfavourable variations in climatic conditions (Sillett, Holmes and Sherry 2000). Climate change is furthermore likely to affect human health and well-being through a variety of mechanisms. For example, it can adversely affect the availability of freshwater, food production, and the distribution and seasonal transmission of vector-borne infectious diseases such as malaria, dengue fever and schistosomiasis. The additional stress of climate change will interact in different ways across regions. It can be expected to reduce the ability of some environmental systems to provide, on a sustained basis, key goods and services needed for successful economic and social development, including adequate food, clean air and water, energy, safe shelter and low levels of diseases (IPCC 2001b).

Carbon dioxide emissions by region, 1998 (million tonnes carbon/year)

Anthropogenic greenhouse gas emissions are unevenly distributed between regions - most emissions come from industrialized regions. Figures include emissions from fuel consumption, gas flaring and cement production

Source: compiled from Marland, Boden and Andres 2001

The United Nations Framework Convention on Climate Change (UNFCCC) adopted at UNCED in 1992 (see Chapter 1) has the ultimate objective of 'stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system' (UNFCCC 1992). The Convention further defines several principles of fundamental importance, for example that parties should take precautionary measures and act 'on the basis of equity and in accordance with their common but differentiated responsibilities'. Being a framework treaty, the UNFCCC contained only a non-binding recommendation for industrialized countries to return to the 1990 emission levels of CO2 and other greenhouse gases (not controlled by the Montreal Protocol) by the year 2000 (UNFCCC 1992). However, most of them have not returned anthropogenic emissions of greenhouse gases to 1990 levels (UNFCCC 2001). In general, global emissions of almost all anthropogenic greenhouse gases, particularly CO2, continue to increase (IEA 2000). This reflects the inadequacy of national and international policies and measures to address climate change.

In its Second Assessment Report, the IPCC stated that the 'balance of evidence suggests that there is a discernible human influence on global climate' (IPCC 1996). This unequivocal statement provided the scientific basis for the adoption of the Kyoto Protocol to the UNFCCC in December 1997. The protocol contains, for the first time, greenhouse gas reduction targets for most industrialized countries. The targets, however, range from an obligation to reduce emissions by 8 per cent (for the European Union and many Central European countries) to a permission to increase emissions by 10 per cent (Iceland) and 8 per cent (Australia). Overall, industrialized countries are required to reduce their aggregated emissions to at least 5 per cent below the 1990 level in the period 2008-12. No new obligations were introduced for developing countries. The Kyoto Protocol also allows collective implementation of obligations by means of applying the so-called 'Kyoto mechanisms'. These mechanisms aim at providing 'geographical flexibility' and reducing the costs of complying with the Kyoto targets. For example, one of them - the Clean Development Mechanism - allows industrialized countries to receive emission credits for carrying out projects aimed at reducing emissions of greenhouse gases in developing countries (UNFCCC 1997).

The background to international cooperation on climate change

Scientists began to attract policy-makers' attention to global warming as an emerging global threat in the early 1970s (SCEP 1970). However their appeals were originally ignored and, as economies grew, more fossil fuels were burnt, more forested areas were cleared for agriculture and more halocarbons were produced. It took a further 20 years of continuous effort by scientists, NGOs, international organizations and several governments to get the international community to agree to coordinated action to address climate change.

The Stockholm Conference is generally regarded as the starting point for international efforts on climate variations and climate change (UN 1972). In 1979, the first World Climate Conference in Geneva expressed concern about the atmospheric commons. This event was attended primarily by scientists and received little attention from policy-makers. In the 1980s, a series of conferences and workshops were held in Villach, Austria, where scenarios for future emissions of all of the significant greenhouse gases were considered. At the 1985 Villach meeting, an international group of scientific experts reached a consensus on the seriousness of the problem and the danger of significant warming (WMO 1986).

As a result of growing public pressure and the implications of the Brundtland Commission (WCED 1987), the problem of global climate change moved onto the political agenda of several governments. A diplomatic breakthrough came at the 1988 Toronto Conference on the Changing Atmosphere from which emerged a recommendation calling on developed nations to reduce CO2 emissions by 20 per cent from 1988 levels by the year 2005. A few months later, IPCC was jointly established by WMO and UNEP to review knowledge of the science, impact, economics of, and the options for mitigating and/or adapting to climate change. The IPCC studies, especially the three extensive Assessment Reports in 1990, 1995 and 2001, covered all the different facets of climate change.

The cost estimates for industrialized countries to implement the Kyoto Protocol range between 0.1 and 2 per cent of GDP in 2010 (IPCC 2001c) with most impact being felt by the economies most dependent on fossil fuels. In view of anticipated economic losses, some industrialized nations have prejudiced the Kyoto commitments and the Kyoto Protocol as a whole. Debates on rules and modalities of the implementation of the protocol continued until the 6th Conference of the Parties to the UNFCCC held in November 2000 in The Hague. As negotiating parties still failed to reach consensus, the conference was suspended and parties decided to resume negotiations in 2001. The pivotal point in the global discussion occurred in March 2001 when the US government decided not to introduce any legal restrictions, as implied by the Kyoto Protocol, on anthropogenic emissions of greenhouse gases. The US administration thus declared its opposition to the Protocol, stating that it believed it to be 'fatally flawed', as it would damage the US economy and it exempted developing countries from fully participating (Coon 2001). This decision meant that the United States - a major emitter of CO2 -would not ratify the Kyoto Protocol.

The Kyoto Protocol would never have come into force if other developed countries had adopted the same position. However, at the resumed 6th Conference of the Parties (COP-6 Part II) in Bonn, Germany, in July 2001, the parties (except the United States) successfully completed negotiations aimed at setting the operational details for commitments on reducing emissions of greenhouse gases. They also reached agreement on actions to strengthen implementation of the UNFCCC itself. The political decision - or Bonn Agreement - was formally adopted by the COP on 25 July 2001. Many saw it as an 'historic' political agreement that saved the Kyoto Protocol and paved the way to its ratification, though it was clearly recognized that this was just a small step towards solving the global problem. Discussions also resulted in a Political Declaration by the European Union, Canada, Iceland, Norway, New Zealand and Switzerland on funding for developing countries. This Declaration includes an undertaking to provide an annual contribution of US$410 million by 2005 (IISD 2001a).

Shortly after COP-6 Part II, the climate change negotiators in Marrakesh (COP-7 held October- November 2001) finalized outstanding issues related to the political deal concluded in Bonn such as a compliance system, the 'Kyoto mechanisms', accounting, reporting and review of information under the Kyoto Protocol, and others (the so-called 'Marrakesh Accords'). The agreement reached in Marrakesh not only allows for ratification of the Kyoto Protocol in the near future but also will serve as the foundation for a comprehensive, multilateral approach that will and must continue beyond this Protocol (IISD 2001b).

Meeting the Kyoto targets will be just a first step in coping with the problem of climate change because it will have a marginal effect on the greenhouse gas concentration in the atmosphere. Even if, in the long term, a stabilization of atmospheric greenhouse gas concentrations is achieved, warming will continue for several decades, and sea levels will continue to rise for centuries with serious consequences for millions of people (IPCC 2001a, b).