Editing IPCC:AR6/WGII/Chapter-14 (section)

==== 14.5.3.3 Adaptation ====

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North American water planners and policy makers have abandoned stationarity assumptions ( [[#Milly--2015|Milly et al., 2015]] ) to address climate change. Transboundary institutions, government agencies and professional organisations are taking the lead on adaptation planning and implementation (ASCE, 2018b; [[#Clamen--2018|Clamen and Macfarlane, 2018]] ; International Joint Commission, 2018). Major water agencies are using climate scenarios to identify vulnerabilities and evaluate adaptation options ( [[#Yates--2015|Yates et al., 2015]] ; [[#Vogel--2016|Vogel et al., 2016]] ; [[#California%20Department%20of%20Water%20Resources--2019|California Department of Water Resources, 2019]] ; [[#Ray--2020|Ray et al., 2020]] ; [[#Bureau%20of%20Reclamation--2021d|Bureau of Reclamation, 2021d]] ).

The Water Utility Climate Alliance advises municipal water providers to address uncertainty by considering a wide range of plausible future climate conditions ( [[#WUCA--2010|WUCA, 2010]] ). In some areas, the impacts of wildfires on water supply resiliency are being considered ( [[#Martin--2016|Martin, 2016]] ). Many North American Indigenous Peoples are engaged in climate-change adaptation planning, although these efforts may be hampered by the complicated legal and administrative setting in which they must operate ( [[#Norton-Smith--2016a|Norton-]] [[#Smith--2016a|Smith et al., 2016a]] ; [[#McNeeley--2017|McNeeley, 2017]] ).

Recent climate extremes have heightened governmental attention to climate-change impacts (e.g., California Natural Resources Agency et al., 2020). Droughts have exposed shortcomings in water management and governance ( [[#Gray--2015|Gray et al., 2015]] ; [[#Xiao--2017b|Xiao et al., 2017b]] ; [[#Lopez-Perez--2018|Lopez-Perez et al., 2018]] ) spurring legislation and administrative changes to improve groundwater regulation and documentation of water rights ( [[#California%20Department%20of%20Food%20and%20Agriculture--2017|California Department of Food and Agriculture, 2017]] ; [[#Miller--2017|Miller, 2017]] ; [[#Lund--2018|Lund et al., 2018]] ; [[#Hanak--2019|Hanak et al., 2019]] ). Water allocation policies are being reassessed to enhance equity, sustainability and flexibility through shortage sharing agreements, improved groundwater regulation and voluntary water transfers. Developments include an interstate drought management agreement for the Colorado River ( [[#US%20Law--2019|US Law, 2019]] ), and agreements between the USA and Mexico to provide pulse flows to benefit the ecology of the Colorado River Delta ( [[#Pitt--2017|Pitt and Kendy, 2017]] ). Statewide water planning in Colorado has emphasised building drought resilience (e.g., by facilitating temporary water transfers) ( [[#Colorado%20State%20Government--2015|Colorado State Government, 2015]] ; [[#Yates--2015|Yates et al., 2015]] ). At local scales, there have been innovations in cooperative watershed protection and water resource planning ( [[#Cantú--2016|Cantú, 2016]] ). Indigenous Peoples are playing an increasing role in identifying equitable and resilient options for adaptation by contributing their knowledge and voicing their perspectives on the importance of healthy water bodies for human and environmental well-being ( [[#Norton-Smith--2016a|Norton-]] [[#Smith--2016a|Smith et al., 2016a]] ; Water and Tribes Initiative, 2020). Collaboration between stakeholders, policymakers and scientists is increasingly common in water resources adaptation planning and assessment.

Examples of adaptation include increasing adoption of water-saving irrigation methods in California ( [[#Cooley--2016|Cooley, 2016]] ), experimentation with using flood waters to enhance groundwater recharge ( [[#Kocis--2017|Kocis and Dahlke, 2017]] ; [[#California%20Department%20of%20Water%20Resources--2018|California Department of Water Resources, 2018]] ) and agricultural land management programmes, including developing riparian buffers to protect water quality ( [[#14.5.4|Section 14.5.4]] ; [[#Mehdi--2015|Mehdi et al., 2015]] ; [[#Schoeneberger--2017|Schoeneberger et al., 2017]] ). Indigenous Peoples are building upon traditional practices to adapt to the effects of climate change, for example, by working jointly to recharge local aquifers ( [[#Basel--2020|Basel et al., 2020]] ).

Water-right laws, interstate compacts and international treaties regarding transboundary water shape the context for climate-change adaptation, but the possibility of long-term climate change typically was not contemplated at their inception. Gaps in coverage and vaguely defined terms can lead to tensions and disputes, especially in areas facing increased aridity, creating difficulties for adaptation. For example, unregulated pumping of groundwater for irrigation during short-term droughts can serve as an adaptation to acute conditions ( [[#14.5.4|Section 14.5.4]] ), but if persisting in the long term, it can deplete finite groundwater resources and de-water hydrologically connected rivers. Such outcomes have engendered bitter and costly interstate conflicts in the USA, some even reaching the US Supreme Court including ''Texas v. New Mexico'' (Rio Grande) and ''Florida v. Georgia'' (Apalachicola-Chattahoochee-Flint).

Transboundary rivers that exemplify the need to address climate impacts include the Colorado ( [[#Gerlak--2013|Gerlak et al., 2013]] ), Columbia ( [[#Cosens--2016|Cosens et al., 2016]] ) and Rio Grande/Rio Bravo ( [[#Mumme--1999|Mumme, 1999]] ; [[#Mumme--2016|Mumme, 2016]] ; [[#Garrick--2018|Garrick et al., 2018]] ; [[#Payne--2020|Payne, 2020]] ). Drought emergencies can open opportunities for progress on collaborative adaptive governance, but such windows may quickly close when wetter conditions return (Sullivan, (2019).

Water serves a wide variety of environmental functions and human uses as it moves through North America’s river basins, so the impacts of climate change are expected to be widespread and multifaceted. This increases the importance of collaborative adaptation efforts that are equitable, transparent and give voice to differing values, perspectives and entitlements across a broad socioeconomic spectrum of urban and rural, Indigenous and non-Indigenous participants ( [[#Miller--2016|Miller et al., 2016]] ; [[#Cosens--2018|Cosens et al., 2018]] ). Adaptation planning may be hampered by conflicting interests, jurisdictional boundaries and inherent interconnections between actions and impacts at different points throughout a watershed or river basin. Differential power relationships, decision-making authority and access to information also can interfere with effective adaptive governance, while equitable processes for decision making bolstered by reliable shared information can help to overcome those impediments ( [[#Cosens--2016|Cosens et al., 2016]] ; [[#Arnold--2017|Arnold et al., 2017]] ; [[#Cosens--2018|Cosens et al., 2018]] ; [[#Porter--2018|Porter and Birdi, 2018]] ).

Across North America, there are growing signs of progress towards adaptive water governance and implementation of climate-resilient, and ecosystem-based, water management solutions ( [[#Colorado%20River%20Basin%20Stakeholders--2015|Colorado River Basin Stakeholders, 2015]] ). California’s approach to groundwater sustainability regulation intends to foster such collaborative problem-solving by giving local Groundwater Sustainability Agencies the authority to design locally appropriate plans to meet state-defined sustainability goals ( [[#State%20of%20California--2014|State of California, 2014]] ; [[#Miller--2017|Miller, 2017]] ). As evidenced by the US interstate disputes, the greatest difficulties arise in cases where stark upstream–downstream differences in interests leave little room for mutual benefit. Severe aridification may test the limits of adaptive capacity.

Research on water diplomacy recommends broadening negotiations beyond a narrow focus on zero-sum issues, like rigid water allocations, to embrace a more diverse set of shared interests including the need for flexibility to respond to changing conditions. A process for ongoing inclusive engagement of a watershed’s stakeholders in mutual social, policy and science learning is important. Such mutual learning can build trust and establish a common platform of credible information for co-creation of adaptation solutions. In addition, better understanding of the policy positions and constraints of others can help stakeholders to identify workable solutions to contentious water management issues ( [[#Payne--2020|Payne, 2020]] ; [[#Wilder--2020|Wilder et al., 2020]] ). Cooperation between Mexico and the USA on mapping and assessment of transboundary aquifers is a product of such ongoing engagement ( [[#Callegary--2018|Callegary et al., 2018]] ; [[#Sanchez--2018|Sanchez et al., 2018]] ). Other examples of the benefits of sustained engagement are provided by a set of co-management arrangements between state, federal and Indigenous authorities on water management for fishery restoration in the US Pacific Northwest ( [[#Tsatsaros--2018|Tsatsaros et al., 2018]] ) and Indigenous involvement in multi-level co-management of water resources in Canada’s Northwest Territories ( [[#Latta--2018|Latta, 2018]] ).

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