impact. The Decadal Survey places a high priority on determining ice sheet volume, sea ice thickness, ice sheet surface velocities, and improved estimates of the sensitivity of the ice sheets to climate change.

Third, the Decadal Survey calls for a focus on the two areas that are considered to be the most limiting in terms of our ability to improve climate model predictions. The first area is aerosol-cloud forcing. Aerosol climate forcing is similar in magnitude to carbon dioxide forcing, but the uncertainty is estimated to be substantially larger. The impact of aerosols on cloud formation amplifies their importance to the climate system. The Decadal Survey also calls for a focus on measuring ocean circulation, ocean heat storage and ocean climate forcing. Again, the problems are fundamental, involving the measurement of sea level, the importance of how rapidly heat is being mixed into the oceans, and improvements in our ability to simulate the ocean circulation.

We are more than capable of providing the observations needed to address the specific topics above. Importantly, the climate chapter of the Decadal Survey also calls for us to address much more challenging problems by bringing innovative approaches to the fore and challenging our ability to return to the cutting-edge of Earth observing. The accurate measurement of the surface fluxes of energy, water and momentum at the Earth’s surface, and an improved ability to examine atmospheric convection (which governs the transport of heat, water vapor, trace gases, and aerosols and defines cloud formation) would substantially advance our ability to predict the future and to understand critical problems such as sea level variations and changes in the distribution and character of precipitation. Missions dedicated to these two important topics are not a part of the priority set from the Decadal Survey.

4. What role, if any, do NASA’s Earth science research and related programs play in validating the accuracy of climate measurements collected from Earth observing satellites and in developing predictive capabilities for climate change and its effects?

The decline in capability is not restricted to missions and instruments. The decline in the observation budget is matched by a significant decline in the Research and Analysis budget in the Earth Sciences. Sub-orbital and land-based studies increase our ability to assess and validate climate measurements. A comprehensive approach to the analysis, distribution and stewardship of observations broadens the base of applications and entrains a broader set of disciplines and a higher level of expertise directed toward increasing our confidence in Earth observations, expanding their value, and improving predictive capabilities.

The loss of capability has the potential to be long-term and particularly costly because of its timing. The lack of missions, the reduced level of opportunities, the lack of innovation, and the weakness in the Research and Analysis budgets are likely to result in a reduction in student interest, and most clearly in the training of graduate students and post-doctoral researchers. This loss of opportunity, with it potential impact on attracting the next generation of scientists and engineers who design sensor systems and analyze data, matches a time in which a substantial fraction of the NASA Earth sciences workforce is able to retire. The FY2008 and out year budgets have the potential to create significant weakness in the capability of the workforce at the same time that society is demanding an increased emphasis on understanding climate and its impacts.

5. What are your perspectives, as an individual researcher, on international collaborations in the Earth sciences, and what value would international collaborations offer in advancing the recommended missions in the decadal survey?

In my opinion, the statements on international collaboration provided in the Decadal Survey are sound. International collaborations have a number of benefits including a reduction in cost and a potential reduction in the likelihood of gaps in key data sets. In addition, collaboration can increase the number of science users and bring a broader array of technologies to bear on a specific problem. NASA has demonstrated success in developing such partnerships, with TOPEX/Poseidon and RADARSAT-1 as good examples. Moreover, it is now relatively common for flight agencies to offer announcements of opportunity to the international science community as the agencies attempt to maximize the payoff of each flight project.

However, joint ventures must still be considered with care, particularly for climate data sets. As noted in the Decadal Survey climate chapter, instruments built by one partner may not be designed to the exact requirements of another partner. Although two missions may utilize the same type of instrument—for example an altimeter—and therefore sound like they are duplicative, the differences in design may allow one to resolve ocean eddies and improve our knowledge of the ocean circulation while the other may not achieve this objective. Technology transfer