The objective of the TOPC Plan is to provide a rationale for the structure and implementation of the initial observing system. It describes the minimum set of terrestrial variables that are required to assess the impacts of, predict, and detect climate change. Annex I to the document contains a detailed description of each of the variables. While it has taken considerable work to arrive at a consensus on this set of variables, it is recognized that these are a beginning. Future meetings of the TOPC will consider other variables and will prioritize this list further. The Plan recognizes that a comprehensive observing system must address the critical variables by making measurements with sufficient and adequate precision, spatial and temporal resolution, and with long-term continuity. The data must be compiled and collated in a fashion that is useful to the users. Ultimately, the products that are produced by GTOS and others must include ones that are in a form that can be easily utilized by policy- and decision-makers. For much of the land and climate system, such comprehensive observations, databases and associated products are not available.
In spite of the fact that a considerable amount of work needs to be done before a comprehensive observation system can be completely implemented for the terrestrial components of the GCOS or the climate portion of the GTOS, a number of actions can be taken to begin implementing some of the required observations. It is clear that with limited resources the TOPC will also need to prioritize implementation actions at a future meeting. Those observations which can be made from space offer the best hope of globally consistent data sets, and consequently research to increase the number and quality of observations that can be made from space is highly encouraged. At the same time, these data must be made readily available to countries that do not have a programme of space-based observations.
The major issue facing GTOS and GCOS to implement a set of climate-related terrestrial observations is to obtain sufficient resources. While the majority of the required observations are already being made at a number of sites, it is clear that for a comprehensive global observing system there will need to be some additional sites established, particularly in the Southern Hemisphere. In addition, other selected sites will need some additional equipment and upgrading. Both GTOS and GCOS central offices are under-staffed and are in the need of additional personnel. These resources must ultimately come from national efforts; the success of these programmes depends on receiving commitments from operational and research funding agencies and national governments.
Since climate affects all nations, it is important to have the participation of all nations. Thus, GCOS and GTOS have made a commitment to fully involve all nations in the programme. In the case of developing countries, the GCOS/GTOS will, in partnership with other programmes, actively support capacity building and training in both making observations and in developing techniques to fully utilize the data and products for national needs.
