detailed estimates of future resource needs and seek the funding necessary to meet its stated objectives. The committee expects that this growth in resources to support the SDS program will be needed primarily in its initial phase because future economies of scale, improvements in the quality and stability of climate sensors, and further experience at sustaining perpetual climate observing systems will allow for a leveling off of support in the future. Once this leveling off takes place, intermittent spikes in funding may be necessary to accommodate major new initiatives or responsibilities.