Managing natural capital assets and ecosystem services under global change

Abstract

Human activities are placing increasing pressure on Earth’s systems and finite natural resources. Climate change alters the provision of ecosystem services and natural capital, so innovative strategies are needed to adapt to these impacts. However, the formulation and implementation of such strategies is hindered by the substantial uncertainty involved in projections of climate change and the impacts this will have. This is confounded by the uncertain impacts of other drivers of change (such as varying demand and commodity prices), which can alter the demand for ecosystem service provision. To add to this challenge, ecosystem services and natural capital assets are not independent of each other, so policies targeting the provision of an individual ecosystem service (such as food production) need to consider the potential impacts they may have on other ecosystem services. I addressed this problem by developing and evaluating strategies to manage multiple ecosystem services under uncertain global drivers of change. In chapter 2 I conducted a systematic literature review of climate change impacts on ecosystem services and found that the impact of climate change on most types of services was predominantly negative, but varied across services, drivers of change, and assessment methods. Although uncertainty was usually incorporated into assessments, there were substantial gaps in the sources of uncertainty included. In addition, relatively few studies integrated decision making, and even fewer studies aimed to include multiple drivers in decisions or identify solutions that were robust to uncertainty. I then addressed decision making under climate change using a case study of conservation planning for coastal wetlands and the ecosystem services they provide under sea level rise in chapters 3 and 4. The expansion of coastal developments can prevent potential landward wetland migration, exacerbating wetland loss as sea levels rise. Pre-emptive planning to set aside key coastal areas for wetland migration is therefore critical for the long-term preservation of species habitat and ecosystem services. In chapter 3 I show that the opportunity cost of preserving wetlands is likely to be much higher under sea level rise than under current sea levels. Nonetheless, payments for ecosystem services were able to alleviate these costs, but even this was hampered with higher rates of sea level rise. I then explicitly incorporated uncertainty in sea level rise projections and modelling of wetland change into a novel problem formulation in chapter 4. I integrated a risk-sensitive resource allocation framework from economics, Modern Portfolio Theory, with a conservation planning framework. This approach allows the selection of a complementary set of connected sites that met a set of conservation objectives whilst hedging the risk of different climate change scenarios and associated uncertainties. I found that planning for specific projections of sea level rise was a relatively high risk strategy, even when planning for the most severe impacts, compared to the risk-sensitive planning approach. Where multiple ecosystem services trade-off against each other, management strategies are needed to balance the relative provision of each ecosystem service, whilst also accounting for different global change scenarios. I exemplified this situation in chapter 5 by using an integrated modelling approach to assess the impact of climate change, fire, and global economic drivers on the profitability and effectiveness of management actions for livestock production and greenhouse gas regulation in the tropical savannas of northern Australia. Emerging strategies, such as changing fire management practices or nitrate supplementation, were able to reduce greenhouse gas emissions, but they came with financial costs. However, the growing urgency to abate emissions under some global change scenarios resulted in prices for carbon that compensated for these costs in some cases. I conclude that innovative methods are vital to successfully adapt the management of ecosystem services to the impacts of climate change and associated complexities. Although the application of such approaches are challenging, ignoring the future impacts of global change can result in the inefficient allocation of resources for climate adaptation and suboptimal management outcomes. Ideally, decision making should also incorporate deep uncertainty and ecosystem service flows to beneficiaries. However, no individual assessment or project can include every complexity, so future research should focus on which drivers, processes, and uncertainties should be prioritised for inclusion in decision making.