Counting on Carbon

A global concern

In New York on 9th May 1992, the UN Framework Convention on Climate Change (UNFCCC) was adopted; to date, the most significant global legal framework for international action to address climate change. By the start of 2002, 186 countries and the European Community had become Parties to the Convention.

The ultimate objective of this Convention is to achieve stabilisation of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic
(man-made) interference with the climate system.

The UNFCCC was strengthened at a meeting of the Conference of the Parties (COP) to the Convention in December 1997, where a legal instrument – named The Kyoto Protocol – was adopted. The Protocol subjects industrialised countries to legally-binding targets to limit their greenhouse gas emissions. These targets add up to a total reduction of 5% in greenhouse gas emissions from 1990 levels, for the five-year period 2008-2012. By the start of 2002, 84 countries had signed; in order to enter into force, the Protocol will have to be ratified by 55 Parties to the Convention, including enough major industrialised Parties to account for at least 55% of the total carbon dioxide emissions by industrialised countries in 1990.

National commitments under the Kyoto Protocol were not offered lightly. The necessary reductions in greenhouse gas emissions will require changes in the way in which countries generate energy, provide transportation, and manage land use – issues which are all fundamental to future economic development. However, the necessary impetus to meet these challenges is the alarming realisation, based on the best available scientific assessment, that human activities are already affecting the Earth’s climate, and that the emission of greenhouse gases is a primary cause.

The term ‘climate change’ usually refers to changes in the climate system, notably a global warming trend caused by emissions of greenhouse gases that create a ‘human-induced greenhouse effect.’ The most important of these gases is carbon dioxide (CO2), which comes mainly from the burning of fossil fuels such as oil, gasoline, natural gas and coal. Other important greenhouse gases include methane (CH4), nitrous oxide (N2O), ozone (O3), and chlorofluorocarbons (CFCs).

As noted in Part I of this document1:

• in 2001 the IPCC suggested that human activity is impacting on our climate, manifested as: changed atmospheric composition; global warming of land and oceans; changed precipitation patterns; increasing frequency of severe weather events, including those attributed to El Niño;
• the IPCC projects that greenhouse gas emissions due to fossil fuel burning are almost certain to be the dominant influence on trends in atmospheric greenhouse gas concentrations in the coming century and that with a ‘business as usual’ scenario, the global average surface temperature is expected to rise at a rate which is most likely without precedent in at least the last 45,000 years. Scientists anticipate profound consequences on sea level rise, precipitation patterns and extreme weather, with consequent impacts on a wide range of ecological functions and human activities essential for individual and societal well-being.

The International Response

The relevant international communities are collaborating on an unprecedented global scale in order to observe, model, and understand the underlying Earth system processes and to implement policy measures to avert the worst effects of the ‘business as usual’ scenario. The main policy initiative is the Kyoto Protocol.

The Kyoto Protocol sets limits on the emission of six main greenhouse gases:

• carbon dioxide (CO2);
• methane (CH4);
• nitrous oxide (N2O);
• hydrofluorocarbons (HFCs);
• perfluorocarbons (PFCs);
• sulphur hexafluoride (SF6).

Some specified activities in the land-use change and forestry sector (namely, afforestation, deforestation and reforestation) that emit or remove carbon dioxide from the atmosphere are also covered. All changes in emissions, and in removals by so-called ‘sinks’ (absorbers), are considered equivalent for accounting purposes

The Protocol also establishes three innovative ‘mechanisms’, known as ‘joint implementation’, ‘emissions trading’ and the ‘clean development mechanism’, which are designed to help Parties reduce the costs of meeting their emissions targets by achieving or acquiring emission reductions more cheaply in other countries than at home. The clean development mechanism also aims to assist developing countries to achieve sustainable development by promoting environmentally-friendly investment in their economies from industrialised country governments and businesses.

The Global Carbon Cycle

Since the dominant influence on future greenhouse gas trends is widely agreed to be the emission of CO2 from fossil fuel burning, an improved understanding of the global carbon cycle has become a policy imperative for the forthcoming decades, both globally and for individual countries.

The global carbon cycle connects the three major components of the Earth system: the atmosphere, oceans, and land. In each domain, large pools of readily exchangeable carbon are stored in various compartments (‘pools’ or ‘sinks’ and ‘sources’). Large amounts of carbon (‘fluxes’) are transferred between the sinks and sources over various time periods, from daily to annual and much longer. Although some of the fluxes are very large, the net change over a given time period need not be. For many centuries prior to the industrial revolution the carbon sinks and sources were more or less in equilibrium, and the net transfer was close to zero for the planet as a whole.

The major changes have occurred following the development of agriculture and industry, with the accelerated transfer from the geological (fossil fuels) and terrestrial pools to the atmosphere. Because of the connections among pools, the increased atmospheric carbon concentration affects the other connected pools in oceans and on land.

The Kyoto Protocol recognises the role of terrestrial systems as carbon sinks and sources, and it provides a basis for developing future ‘emission trading arrangements’ that involve forests and potentially other ecosystems. Understanding of the pathways through which the anthropogenic CO2 is absorbed from the atmosphere and into ecosystems (thus offsetting a portion of the anthropogenic emissions) is fragmentary and incomplete. These factors and dependencies make the quantification and study of the carbon cycle very challenging to model, observe, and predict.

Observing the carbon cycle

The UNFCCC and the Kyoto Protocol represent the first attempt by mankind, acting collaboratively across the world, to manage, at least partly, a global element cycle of the Earth system – the global carbon cycle.

This challenge requires the support of a coordinated set of international activities – scientific research (including modelling), observation, and assessment. Assessment is perhaps the most advanced, with the pioneering work of the IPCC providing the scientific assessment required for the policy action. In terms of scientific research, the International Geosphere-Biosphere Programme (IGBP) has recently joined forces with the International Human Dimensions Programme on Global Environmental Change (IHDP) and the World Climate Research Programme (WCRP) to build an international framework for integrated research on the carbon cycle (a project called Carbon 21).

A key element of international carbon activities – an integrated strategy for the observation of the global carbon cycle, including the land, oceans, atmosphere compartments of the cycle, is being coordinated by the IGOS Partnership, within the Integrated Global Carbon Observations (IGCO) Theme (see annex B for more on IGOS Themes).

A broad range of observations of important atmospheric, oceanic, and terrestrial parameters are required to: support future policy-making with evidence of trends; monitor the legal commitments undertaken within the Kyoto Protocol or future treaties; improve scientific understanding of the underlying processes. The same observations are important requirements for sustainable development and resource management.

The IGCO Theme will build on a number of carbon cycle observation initiatives at the Earth’s surface which are underway or planned, including:

• global networks of atmospheric greenhouse gas measurement stations (such as GLOBALVIEW CO2), and the WMO World Data Center for Greenhouse Gases (Tokyo);
• global networks of measurement tower sites that monitor the exchanges of CO2, water vapor, and energy between terrestrial ecosystems and atmosphere; eg the FLUXNET system has over 150 tower sites operating on a long-term and continuous basis;
• measurement ships and arrays of buoys, including the TAO array in the equatorial Pacific.

The role of Earth observation satellites

Data from Earth observation satellites provide the only global, synoptic view of key measures of the carbon cycle, and form an essential and central part of the envisaged integrated observation strategy planned within IGCO.

The major applications include:

• global mapping of land cover use, land cover change, and vegetation cover characteristics which are important to full carbon accounting – using sensors such as AATSR, AVHRR, ETM+ and MODIS and carried out through the Global Observation of Forest Cover (GOFC) project initiated by CEOS;
• seasonal growth characteristics, including important parameters such as Leaf Area Index (LAI) are generated on a global scale (eg by AVHRR);
• fire detection and burn scar mapping: in many regions of the world, fires are the most significant disturbance of vegetation and drive large inter-annual variations in carbon emissions from ecosystems; large fires in forests and grasslands are detected and mapped from space using thermal and optical sensors (radar sensors also show promise for burn mapping);
• combinations of satellite measurements of parameters such as ocean chlorophyll, dissolved organic matter, and pigment composition and physical measurements from satellite of ocean waves, winds, temperature are used to derive three main contributions for the study of ocean carbon:
  – quantifying upper ocean biomass and ocean primary productivity;
  – providing a synoptic link between the ocean ecosystem and physical processes;
  – quantifying air-sea CO2 flux.

The most challenging aspect of observing the carbon cycle from space is the development of instruments for monitoring total column CO2 concentration with complete coverage.

Future challenges

Future challenges relating to the global carbon cycle include:

• institutional: the continuing need for mechanisms for its management which are acceptable to all countries;
• scientific: improved understanding of the global carbon cycle is vital, including the ability to observe changes in carbon cycle dynamics;
• ensuring continuity of Earth observations.

Future plans for next generation Earth observation satellites include:

• a move from research to operational status for key observations, to support international policy frameworks, and to maintain the necessary continuity;
• development of future measurement capabilities: eg measurements of global vegetation characteristics and biomass, using lidar (laser radar instruments, such as NASA’s proposed Vegetation Canopy Lidar – VCL) and new multi-directional, multi-spectral instruments (such as SPECTRA planned by ESA);
• measurement of atmospheric CO2 concentration from space, globally in a comprehensive and consistent way.

The necessary coordination of the relevant satellite missions will be undertaken by CEOS including through their participation in the IGCO Theme. Part III of this document summarises the various plans of the world’s space agencies.