The Biosphere: A Decadal Vision

David L. Peterson, NASA Ames Research Center, Moffett Field CA 94035 Paul J. Curran, Southampton University, Southampton, UK Marty Mlynzcak, Langley Research Center, Hampton VA 23681 Richard Miller, Stennis Space Center, MS 39529

I. INTRODUCTION and interactive modeling can play in developing our While space scientists renew the hunt for a living planet, understanding of Earth and its the living systems. Earth science has launched the grandest study ever con- Ecological principles were laid down only a few ceived of the only living planet we know, our home planet decades ago with the 1929 publication of the book by Earth. This study is truly one at a planetary scale involving Vernadsky.[l]. Ecology is the science of how the Earth’s programs and people from around the world and techno- vegetation and animals assemble into organized internally logies and modeling barely envisioned just 25 years ago. competing systems interacting within environmental con- Earth startlingly differs from our solar system neighbors straints. The co-evolution of ecosystems with the environ- because of the presence and power of life, life which ment provides many clues to our future. Today, for the first influences virtually every system on Earth. Biospheric time, satellites can measure in a routine way some key pro- processes on the land, in the coastal zone and in the open perties of ecosystems. These observations are enabling the ocean exert an influence on Earth’s climate system and prediction of a number of important processes: land use, climate, in turn, exerts a strong effect on the biosphere and land cover, parts of the carbon and water budgets, and how it is structured and functions. The biosphere, and life in carbon exchange with aquatic systems. But, the required general, depend to a great extent on the presence of liquid satellite observations needed is far from complete. Just to water. Changes in climate as well as changes in the bio- permit a knowledgeable analysis of how the biosphere, sphere are beginning to affect many aspects of the Earth’s water cycle and the climate system interact with an hydrologic systems, in particular the delivery of one of the assessment of the influences of human actions demands smallest fractions, fresh water. These interactions have a much more than is currently planned. Further, a more robust new and complicating force, the transformational power of satellite program is required to address the manner in which the growing human population and spirit. And, ultimately, this knowledge can be used to sustain support for all of how these changes influence the fate and health of the Earth’s living systems, including humans. The long lead human population is itself compelling. time for satellite programs means the low priority currently To a great extent, the space agencies have pursued being afforded to advanced remote sensing for biospheric an old and familiar object, the climate system. From the measurements will stretch the time needed to gain a earliest days of space observations, Earth’s weather and complete global understanding of this interaction. climate systems have focused the attention of agencies and While the biological systems of the open ocean and the public. And, still today, to a large extent the central the coastal zone are vital to understand and predict, the focus of the space-based global science programs are availability of fresh water is a growing international and concentrated on the climate system. The focus is different in policy concern. As Matthews [4] articulates so clearly, the International Geosphere Biosphere Programme, a found- resources will become an increasingly important part of ing program of the study of global change. While climate future national security policy, with the access to and effects and influences are clearly stated, there is a greater maintenance of fresh water supplies one of the most urgent. balance between geospheric and biospheric concerns. One Mirroring the growth of human population and technology, of the net effects is a loss of priority in the space camp for human demands for fresh water for agriculture and observations needed for a fuller study of the biosphere. household uses has been growing dramatically these last 50 This paper focuses on biosphere-climate interac- years. Climate change and global warming can alter the tions including the influences of human activities. Recog- patterns of precipitation delivery, timing, state and quantity nizing this is only one aspect of biospheric processes, this in ways that are likely to exacerbate fresh water supplies. places an emphasis of those biogeochemical processes that Impoundments and diversions are a supply solution with have a profound effect on numerous other aspects of the their own consequences, including the diversion of silt away biosphere and the services it provides, services which are from the coastal environments as well as the total amount of critical to sustaining life on Earth. And, the paper will focus fresh water to mix with salt water. The cleansing of water is on the various scientific aspects of assessing the availability a function of the ecosystem in the contributing watersheds. of fresh water, including its sensitivity to climate variance The effects of human manipulation of terrestrial ecosystems and land use changes. Finally, this paper hopes to emphasize worldwide has impacts on fresh water quality and amount the potential role that greatly expanded space observations that are not well understood. And, the control of fresh water systems has important effects on the biological systems in wetlands, streams, lakes and rivers that depend on uncertainties in climate projections.” One of the long-term evolutionary adaptations to the characteristics of these questions of the USGCRP Changing Ecosystems program systems. Lastly, human interactions with fresh water element is “how do natural and human-induced changes in organisms can have profound human health implications. the environment interact to affect the structure, functioning, Many vectors of infectious disease, such as malaria, and services of ecosystems at a range of spatial and schistosomiasis, cholera and more have a critical link to the temporal scales, including those functions that can in turn patterns and condition of fresh water systems. influence regional and global climate.” The National Science Foundation of the U.S. has a n. CURRENT PLANS (NEXT DECADE) research program originally called the Freshwater Initiative There is quite a bit of consensus among international to initiate research on many aspects of fresh water hydro- programs on research priorities for terrestrial ecosystems, logy, watershed health, and freshwater ecology. The the coastal zone, and the open ocean. A significant portion USGCRP Global Water Cycle Program Element lists these of these objectives concern the interactions of the structure focus areas: (1) the effects of large-scale changes in land use and function of ecosystems with the climate system and and climate on the capacity of societies to provide adequate changes in it, and the added complications of the human supplies of clean water; and, (2)how natural processes and dimensions. For example, the objectives of long-term pro- human activities influence the distribution and quality of grams of the International Geosphere Biosphere Programme water within the Earth system and to what extent the resul- (IGBP) address this question including Global Climate and tant changes are predictable. The USCCRP reiterates these, Terrestrial Ecosystems (GCTE), Global Environmental adding concern about the movement of sediments, biogeo- Change and Food Systems (GECaFS), and Biospheric chemical and toxic subtances, and nutrient transport. These Aspects of the Hydrological Cycle (BAHC). Recently, programs stress the need for research to inform policy IGBP initiated the Integrated Land Ecosystem-Atmosphere debates and enter decision processes for water management. Processes Study (ILEAPS) whose goals is “to provide IGBP recently completed the Biospheric Aspects understanding of how interacting physical, chemical and of the Hydrologic Cycle, integrating parts into the ILEAPS biological processes transport and transform energy and and Global Energy and Water Cycle Experiment (GEWEX) matter through the land-atmosphere interface.” The second of the World Climate Research Program. Much of the phase of IGBP’s Land Ocean Interactions in the Coastal research was concentrated on the water balance and role of Zone (LOICZ) Program addresses five themes: (l), river vegetation in regulating that balance. basins and human dimensions; (2), coastal development and The European community, while largely in agree- change: Implications for landsea use; (3), fate and trans- ment with the biosphere-climate interactions as discussed in formation of materials in coastal and shelf waters; (4), NASA’s 2030 vision, has three important areas of diver- towards system sustainability and resource management; gence. First, what is the role of agricultural lands and not and, (9,vulnerability of coastal systems and human safety. just semi-natural vegetation, in the study of biosphere/ The IGBP maintains other studies of the ocean including the climate interactions? Remote sensing has a role to play at Joint Global Ocean Flux Study concerned with the fluxes of the scale of the field and farm where environmental changes materials and energy between the ocean and the atmosphere. in space and time are relatively small, ground data are The United States Global Change Research plentiful and environmental understanding is already strong. Program (www. usecm.eov, Changing Ecosystems chapter), Increasingly, however, it is being used at the regional to as well as the U.S. Climate Change Research Program global scale where environmental changes in space and time (USCCRP), is focused on climate with substantial attention are relatively large, ground data are sparse and environ- on biosphere interactions. Under USGCRP, regarding the mental understanding is non-existent to poor [3]. At the reduction of uncertainties in climate prediction, the field to farm scale remotely sensed data are often useful but sensitivity to unresolved ocean processes is of particular at the regional to global scale they can often be the only data note. “Because of computer resolution, none of the current source and so are vital. This facility to provide internally coupled climate models resolve the small ocean eddies (with consistent synoptic data at a range of scales has given agri- horizontal scales of tens of kilometers) that constitute the cultural remote sensing a major r61e in answering two of the dominant scale of oceanic variability. These eddies are largest (and interlinked) questions of our time: ‘How does thought to play a substantial role in regulating oceanic heat our planet work?’ (Le., how does the Earth system function, transport (via boundary currents) and heat and carbon how is it changing and what are the consequences for life on storage by regu-lating transport to deep waters. A series of Earth? [5])and ‘whither sustainable agriculture?’ (Le., how eddy-resolving global ocean sensitivity studies are required do we invent a future in which food security is achievable to assess how well the parameterization of in current climate for all in an environmentally stable way?[2]). models portray the ocean’s sensitivity to forcing.” This Second, there is an uncertainty about our ability to planning document says “climate sensitivity is a measure of produce a law-like Earth System Model. A vision of the the climate’s response to a unit change in radiative forcing Earth Science Enterprise is long term prediction. Such due, for example, to changing atmospheric concentrations of predictions could include the effect of climate change on greenhouse gases. It accounts for a major part of the crop yield, insect populations and storm frequency at some place and time in the future. Such predictions would be productivity have shown a world-wide trend of increasing need-driven and would necessitate a change in approach. length of growing season’ above 40 degrees N lat. A global While prediction is linked epistemologically and historically Landsat data base for quantitative assessment of land cover to science it is not essential and is just becoming a part of has been created. Models of ecological and bio-geochemical the biologicalEarth science tradition that characterizes cycling have been established that use remote-ly sensed much agricultural/environmental research. This raises parameters. A fire occurrence product is posted daily from conceptual difficulties for formulating and promoting an Terra MODIS data. Global ocean chlorophyll and sea Earth system modeling agenda. The lay/ political audience surface temperature are being assembled from two satellites, who ultimately support such research do so in the hope that SeaWiFS and Terra MODIS. These data are being used in piece by piece we can understand how our planet works and models of open ocean carbon exchange. when we know then we will know what it will do many Over the next ten years, emphasis will shift to years hence. However, the Earth is complex, every rela- quantifying the seasonal and interannual variations in the tionship is dependent on external influences, so that long- state of carbon sources and sinks including the coastal ocean term predictions defy testing [I]. Thus, this research may be and the Southern Ocean. A new satellite, the Orbital Carbon unlikely to result in law-like predictions. The emphasis is Observatory, will be launched to measure atmospheric more likely to be on the use of model-derived estimates with profiles of C02 as a constraint on carbon budgets. Carbon uncertainties [8, IO] within a need-driven technological assimilation models will be expanded to incorporate new approach (NASA, 2002).and third, most importantly, the understanding of tropical ecosystems and to couple models importance of sustainable development as a political vehicle with ocean and atmospheric processes (teleconnec-tions). for Earth observation developments is paramount. The remote sensing of ecosystems will focus on Both the IGBP and the USGCRF’ explicitly state identification and characterization of plant species the role of space observations in achieving a global view of functional groups and physiological state for the land, algal biosphere-climate interactions. For the United States, the blooms and carbon sequestration for marine ecosystems, agency charged with providing the satellite observations is and forecasts of how ecosystems will respond to multiple largely NASA. NASA is in the midst of launching the Earth stressors. And, repeated Landsat inventories will help to Observing System (EOS) to provide a comprehensive data determine the trends in land use change, its causes and the set of climate relevant variables. The priorities of NASA’s trajectories of response, and the consequences for carbon Earth Science Enterprise have been concentrated on climate storage and sequestration. Much of this work is aimed at change and solid Earthhatural hazards research (NASA, providing scientifically sound information for policy setting 2000). This will remain the focus for the next ten years as and for decision support systems to implement policy and NASA works with its public and commercial partners in the other landlocean management objectives. U.S. and internationally to provide the first long term data Freshwater systems: base of 24 key parameters. The program is organized to get While one of the focus areas of the NASA program is the answers to questions in six specific focus areas: (a) How can water cycle, the ultimate aim of this research is not to predictions of climate variability and change be improved? determine the regional distribution of fresh water (b) How will future changes in atmospheric composition availability. Instead it focuses on the role of water and affect ozone, climate, and air quality? (c) How will carbon energy in the global climate system with aims to improve cycle dynamics and terrestrial and marine ecosystems the prediction and measurement of precipitation, change in the future? (d) How will water and energy cycle evaporation rates and so forth. A few groups have used dynamics change in the future? (e) How can weather digital terrain model data to assemble systems to map forecast duration and reliability be improved? and (0How hydrologic patterns down to small watersheds. The can our knowledge of Earth surface change be used to prediction of water yield from vegetated watersheds has predict and mitigate natural hazards? been successful from small catchments to very large river systems. In general, the uses of remote sensing to HI. NEAR TERM SCIENCE PROGRAMS characterize fresh water yield and quality, to forecast Terrestrial and Marine Ecosystems: drought or flooding, to assess effects of changes in water The ten year U.S. research program in ecosystems stresses flow volumes on fisheries and other aquatic systems is still the carbon exchange dynamics of North America’s terres- largely undeveloped. trial ecosystems and the open ocean. While NASA’s bio- sphere programs are linked with those of the National IV. A DECADAL VIEW Science Foundation and other U.S. agencies. The recent Looking out to 2030, will the present suite of satellite NASA program has made substantial progress. A long-term sensors and research foci be sufficient to answer the observational program has been developed to generate questions of how the biosphere and the climate system “climate quality” information on ecosystems, primary pro- interact, what the availability of fresh water will be, and ductivity, and carbon properties (e.g., ocean color, veg index what the influences will be from human actions? Probably and land cover). Various satellite data driven analyses of the not. By early in the next decade, the science understanding major seasonal and interannual variations in terrestrial of the carbon cycle will be greatly improved but it will still lack critical measurements. Certainly net primary produc- adapted ecosystems. Hillslopes denuded of vegetation have tion will be further along, but probably not, net ecosystem dramatically reduced capability to absorb rainfall, so that production in which there is an explicit estimation of below- large mass flows can follow fires, clogging reservoirs and ground respiration and maybe not, maintenance respiration. rivers, and reducing water quality. Current sensors are There will be an enhanced global understanding of COz and incapable of measuring the most important properties of water vapor exchange and (2% production and consump- fire, those with predictive power, even though these sensors tion; but not other important trace gases: N20, NO, CO, can provide a rough estimate of fire occurrence. NMHC, VOCs, and NH3. What biogeochemical processes The coastal zone has been largely neglected in regulate these fluxes? Are these processes measurable by satellite planning. Sensors optimized for the open ocean remote sensing and how much do human actions affect have limited utility in the shallower and often turbid waters them? And, some progress can be expected on estimating of the coastal zone, a marine system closely coupled to the precipitation and some components of the water cycle. land. These two ecological domains do share some common One of the most evident effects of human activity unmet measurement needs, namely, mixed layer depth, is the transformation of the landscape into uses almost nutrient fields, salinity, and physiolog-ical state. Though a exclusively for the benefit of humankind. At present we can number of organizations have stated their intention to lay down an historical record of land cover and try to infer launch satellites to monitor the coastal zone, as of 2003, land use. But we are not well prepared to predict the course none have succeeded (Peterson et al., 2003). of ecosystem restoration or the trajectory of response, nor The new or additional measurement requirements the possibilities that an ecosystem will enter a new and for the biosphere are listed in table 1. Though there is stable state resistant to restoration. And, what will be the discussion of some of the space technology to make these consequences of these changed landscapes and the measurements and even some low Technology Readiness ecosystem services they are supposed to provide for the Level space experiments (notably, the Hyperion generation of fresh water supplies? hyperspectral imaging spectrometer on EO-1); NASA does Another event as old as the ages is fire, a force now not have a coherent plan to accomplish the difficult suite of dominated by humans today with tremendous transforma- measurements described. Commercial companies are now tion power. Fires produce substantial though poorly under- providing some high spatial resolution observations. And, stood fluxes of gases and particulates into the troposphere; most of these measurements have been demonstrated from and can lead to permanent change in ecosystem structure airborne platforms, though even those rarely are optimized and function. It is also an agent for beneficial change in fire- for specific biological phenomena.

Tab1 Measurements Frequency Technology Needs OCEANS Mixed layer depth, wind fields, salinity Daily Active sensors image through clouds, lidar sensors Nutrient fields (N, Si, Fe), aerosol deposition, Weekly Passive sensors hnctional groups COASTAL ZONE Colored dissolved organic matter; Chlorophyll and Daily-Weekly Hyperspectral (350-900nm) (also: other pigments; Functional groups; Bathymetry radiometry) and bottom reflectance; Nutrient concentration (N, Si, Fe, P) Physiological state (fluorescence) Daily Space-based passive fluorometer Or excitement/emission fluorometer

ignm, pigmen . J

Table 2 lists measurement requirements for fresh water most challenging will be soil moisture, how to assess soil assessment. Most of the required measurements are not moisture on a continuous basis down to the rooting depth of planned nor do they have priority, except those associated most plants, about one meter. The only plans going forward with natural hazards (sea ice thickness, ice sheet thickness, today are a combination of in situ sampling and remote snow pack and ice sheet topographic change). One of the sensing for some form of extrapolation.

Table 2. New measurements for Fresh Water Availabilitv

I Ice sheet topographic change 1

New Modeline Required Gross primary production models of the open atmosphere, they are now based too heavily on correlates to ocean are based on absorption of photosynthetically active NPP. Modeling of life cycle community structure, based on radiation in the photic zone and on the sea surface remote sensing data, is less well developed and eventually temperature. The future models will include functional must be coupled with the ecophysiological models. Future groups with different rates of efficiency, mixed layer depth, community models will be needed to predict the trajectories nutrient fields (N, Si, Fe), and aerosol deposition. Carbon of ecosystem response to change, including climatic, land sequestration to the deep ocean is based on knowledge of use, multiple stressors, species invasions and so forth. ocean heat transport and circulation patterns. Future Radiative transfer models must be improved to enable modeling capabilities must integrate mixed layer depth to forward prediction of ecosystem variables from the remote elucidate the trophic levels of fish and microbiotic species. sensing signals. Such models are needed for not only the Once in the coastal zone, the spatial resolution of many properties of intact and healthy ecosystems, but for all of the processes decreases. This zone is subject to episodic altered and disturbed states caused by natural and human discharge events from the land, which can change the color induced causes including fire behavior. As these models of the waters and their clarity. Models will be needed of mature and are tested against calibrated data, the models nutrient redistribution and hypersaline flows. Improvements should allow researchers to better assess the consequences in bio-optical and radiation transport must be improved, of human interactions: fires, land conversions, grazing, considering the possibility of bottom reflectance signals, over-utilization, soil degradation, selective and complete Case 2 waters, and riverine inputs. harvesting, acidic precipitation, as well as climate variation. Ecopyhysiological models of terrestrial ecosystems In the end, once such models are integrated with other are improving, on track to predict net primary production components of the Earth system model and further and related indices of carbon exchange based on remotely intelligence is added on ecosystem services, the modeling sensed variables. These models are based on short-term suite might be ready to address, in conjunction with the processes and while they are being used to predict the greatly enlarged satellite data set, to address numerous production of a host of biogenic gases to and from the practical questions in the terrestrial biosphere.

Table 3. Summary of short term prediction goals enabled by an Earth System Model in 2030. The prediction goals listed below illustrate the improvements extending from the present capabilities towards those expected, circa 2030.

Today 2010 2030 Availability of Water First measurements of some Global precipitation Global precipitation, H20, components of the global measurements: Global evaporation, ice sheet extent, hydrological cycle: Precipitation, atmospheric water vapor quantitative precipitation Ice Sheets, SST. measurements forecasts 1 year out. Allocation of fresh water to mul- First order estimates of fresh Modeling of fresh water produc- tiple uses poorly understood with water allocation and storage tion, regional distribution and remote sensing .Hydrologic yield Prediction of the hydro-logical shortages. Modeling of ecosystem yield and water budgets of processes that produce fresh understood and modeled regional to large watersheds water and affect water quality

1 Biosphere-climate Interactions Prediction of high resolution, Observations of “climate quality” Carbon sources and sinks for monthly biosphere-atmosphere ecosystem variables allow North America for carbon exchange of gases, aerosols and management decisions based on relating net primary production energy by oceans, coastal zone, with carbon balance. reduced uncertainties and terrestrial biosphere Predictive understanding of the First-order characterization of Effects of land use change and natural and human-induced annual biogeochemical cycling biomass recovery on carbon regulatory controls on biospheric and biospheric processes for balance with carbon pools processes (climate variability, carbon in open ocean and assessed; and, accurate biogeochemical cycles, soil loss, terrestrial models based on measurement of carbon exchange hydrology, radiation and land- remote sensing data and pools for the coastal zone ocean margins) Knowledge of statistical Forecasting of ecosystem Capacity to forecast the human teleconnections between climate response to climate and weather influences on the biosphere- variability and indices and variability on interannual and atmosphere exchange and biogeochemical cycles. ecosystem responses. longer time scales. Predictive, fully interactive bio- Carbon process and carbon sphere modeling at fine space1 Coarse resolution, global net management modeling and time scales responsing to climate primary production modeling for forecasting capability that is variation and human effects (pub- terrestrial and open ocean ecosystem specific and accounts lic health, productivity, biological ecosystems. for disturbance processes (fire invasions, disaster monitoring, and land use to first order). and ecosystem services)

CONCLUSIONS [2] Cartwright, N. ed. (2002) The Big Questions in Science. There is some mis-balance between the priorities of the Johnathan Cape, London. space programs, particularly NASA, and the international [3]Curran, P.J. and Foody, G.M. (1994) Environmental programs such as the International Geosphere Biosphere issues at regional to global scales. In Foody, G.M. and Program about the appropriate commitment to biospheric Curran, P.J. (eds) Environmental Remote Sensingfiom and fresh water science. The former is strongly concentrated Regional to Global Scales. Wiley, Chichester: 1-7. on climate change and natural hazards for NASA, while the [4] Matthews, J.T. 1989. Redefining national security. latter has a greater emphasis on all of the aspects of the Foreign Afairs 68(2): 175-185. influence of the living systems on the Earth system. Since [SINASA. 2000. Exploring our Home Planet: Earth Science satellite programs are generally long lead time programs and Enterprise. NASA, Washington DC. costly, it could be some time before this apparent imbalance [6]NASA. 2002. Earth Science Enterprise Applications might be rectified. The study of a living planet at such a Strategv for 2002-2012. NASA, Washington DC. planetary scale must give due attention to the living part to [7] Peterson, D.L.et al. Platform options of free-flying make up a legitimate and accurate picture of how the system satellites, UAVs or the International Space Station for functions and will evolve into a future dominated by human remote sensing assessment of the littoral zone, Int ’I Journal influences. This paper attempts to illustrate some measure- ofRemote Sensing, in press, 2003. ment steps and modeling improvements that might move us [SISkidmore, A. ed. 2002. Environmental Modelling with toward this more complete picture. And, hopefully, provide GIs and Remote Sensing. Taylor and Francis, London. the kinds of data and models that will allow us to respond to [9] Vemadsky, V.I. 1998. The Biosphere. Copemicus the changes that are sure to come in the near future. Books, Jan., 1998 (new translation). [lo] Wicks, T. and Curran, P.J. 2002. Flipping forests: References: [ 11 Byerly Jr, R. (2000) Prediction and charac- estimating future carbon sequestration of the boreal forest teristic times. In Sarewitz, D., Pielke Jr, R.A. and Byerly Jr, using remotely sensed data. International Journal of R. (eds) Prediction, Science, Decision Making and the Remote Sensing (in press). Future of the Nation. Island Press, Wash. DC:327-340.