Oceans and Marine Resources in a Changing Climate

A Technical Input to the 2013 National Climate Assessment

Roger Griffis, Jennifer Howard, Roger Griffis, Jennifer Howard

• Publisher: NCA Regional Input Reports
• Year: 2013
• Print ISBN: 9781610914345
• eBook ISBN: 9781610914802
• Topic: Biological Sciences
• Subtopic: Environmental Science
• Index: Biological Sciences

Prepared for the 2013 National Climate Assessment and a landmark study in terms of its breadth and depth of coverage, Oceans and Marine Resources in a Changing Climate is the result of a collaboration among numerous local, state, federal, and nongovernmental agencies to develop a comprehensive, state of the art look at the effects of climate change on the oceans and marine ecosystems under U.S. jurisdiction.

This book provides an assessment of scientific knowledge of the current and projected impacts of climate change and ocean acidification on the physical, chemical, and biological components and human uses of marine ecosystems under U.S. jurisdiction. It also provides assessment of the international implications for the U.S. due to climate impacts on ocean ecosystems and of efforts to prepare for and adapt to climate and acidification impacts on ocean ecosystem, including
·         Climate-Driven Physical and Chemical Changes in Marine Ecosystems
·         Impacts of Climate Change on Marine Organisms
·         Impacts of Climate Change on Human Uses of the Ocean
·         International Implications of Climate Change
·         Ocean Management Challenges, Adaptation Approaches, and Opportunities in a Changing Climate
·         Sustaining the Assessment of Climate Impacts on Oceans and Marine Resources

Rich in science and case studies, it examines the latest climate change impacts, scenarios, vulnerabilities, and adaptive capacity and offers decision makers and stakeholders a substantial basis from which to make informed choices that will affect the well-being of the region's inhabitants in the decades to come.

Chapter 1

Introduction

The U.S. is an ocean nation—our past, present and future are inextricably connected to and dependent on oceans and marine resources. Marine ecosystems of the U.S. support an incredible diversity of species and habitats (NMFS, 2009a, b) and provide many valuable ecosystem services, including jobs, food, transportation routes, recreational opportunities, health benefits, climate regulation, and cultural heritages, that affect people, communities, and economies across America every day and that affect the nation’s international relations in many ways (NOC, 2012; NMFS, 2011; U.S. USCOP, 2004). In 2004, the ocean-dependent economy, which is divided into six industrial sectors, generated $138 billion or 1.2 percent of U.S. Gross Domestic Product (GDP) (Kildow et al., 2009). U.S. ocean areas are also inherently connected with the nation’s vital coastal counties, which make up only 18 percent of the U.S. land area but are home to 36 percent of the U.S. population and account for over 40 percent of the national economic output (Kildow et al., 2009).

Marine ecosystems under U.S. sovereignty generally extend from the shore to 203 nautical miles seaward including areas under State (0-3 nautical miles except 0-9 nautical miles off the shores of Texas, the Gulf Coast of Florida, and Puerto Rico) and federal (3-200 nautical miles) jurisdiction. The area under federal jurisdiction spans 3.4 million square nautical miles of ocean, an area referred to as the U.S. exclusive economic zone (EEZ) (National Marine Fisheries Service, 2009a). The U.S. has the largest EEZ in the world, an area 1.7 times the land area of the continental U.S. and encompassing 11 different large marine ecosystems (LMEs) (Figure 1-1).

These valuable marine ecosystems and services are increasingly at risk from a variety of human pressures, including climate change and ocean acidification. Climate change and acidification are affecting oceans in a number of ways over multiple temporal and spatial scales (Figure 1-2a) (Doney et al., 2012; Osgood, 2008). In addition, non-climatic stressors resulting from a variety of human activities, including pollution, fishing impacts, and over-use, can interact with and exacerbate impacts of climate change. Collectively, climatic and non-climatic pressures are having profound and diverse impacts on marine ecosystems (Figure 1-2b). These impacts are expected to increase in the future with continued changes in the global climate system and increases in human population levels.

Climate change is affecting ocean physical, chemical, and biological systems, as well as human uses of these systems. Rising levels of atmospheric CO₂ is one of the most serious problems because its effects are globally pervasive and irreversible on ecological timescales (NRC, 2011). The two primary direct consequences of increased atmospheric CO₂ in marine ecosystems are increasing ocean temperatures (IPCC, 2007a) and acidity (Doney et al., 2009). Increasing temperatures produce a variety of other ocean changes including rising sea level, increasing ocean stratification, decreased extent of sea ice, and altered patterns of ocean circulation, storms, precipitation, and freshwater input (Doney et al., 2012). These and other changes in ocean physical and chemical conditions, such as changes in oxygen concentrations and nutrient availability, are impacting a variety of ocean biological features including primary production, phenology, species distribution, species interactions, and community composition, which in turn can impact vital ocean services across the Nation (Figure 1-3). Projections of future change show that it is likely that marine ecosystems under U.S. jurisdiction and U.S. interest internationally will continue to be affected by anthropogenic-driven climate change and rising levels of atmospheric CO₂. Interactions of climate impacts vary by region and complexity. Figure 1-4 is an illustrative example of this in the California Current.

Figure 1-1 Large marine ecosystems within the U.S. Exclusive Economic Zone (NOAA Fisheries 2009c).

1.1 Scope and Purpose

This report provides an assessment of current scientific knowledge on the climate impacts, vulnerabilities, and adaptation efforts related to U.S. oceans and marine resources. The report was produced by a team of experts charged with synthesizing and assessing climate-related impacts on U.S. oceans and marine resources as a contribution to the third National Climate Assessment (NCA), which was conducted under the auspices of the U.S. Global Change Research Program (USGCRP). The U.S. Global Change Research Act of 1990 requires that periodic national climate assessments be conducted and submitted to the President and the Congress. Two previous national assessment reports published in 2000 and 2009 contained little information on climate impacts on U.S. oceans and marine resources. This report is intended to increase understanding and emphasis on this topic for the 2013 NCA.

Figure 1-2 (a) Changes in (1) global mean sea level (data starting in 1800 with an upward trend; Jevrejeva et al., 2008), (2) summer Arctic sea-ice area (data starting just prior to 1900 with a downward trend; Walsh and Chapman, 2001),(3) 0-700-m ocean heat content (data starting around the mid 1900's with an upward trend; Levitus et al., 2009),(4) sea-surface temperature (data starting around the mid-1800's with a general upward trend; Rayner et al., 2006), (5) mean ocean surface pH (data starting around 1000 with an downward trend into the future; NRC, 2010b), and (6) pCO₂ (data starting around 1000 with an upward trend tinto the future; Petit et al., 1999). Shaded region denotes projected changes in pH and pCO₂ consistent with the Intergovernmental Panel on Climate Change’s 21^st-century A2 emissions scenario with rapid population growth. (b) Time series (as identified in figure key): trends in world population (solid line, data starting in the 1800s with an upward trend; Goldewijk, 2005), U.S. coastal population (solid line, data staring in the 1950s with a general upward trend; Wilson and Fischetti, 2010), anthropogenic nitrogen fixation (solid line, data starting in the late 1850s with a general upward trend; Davidson, 2009), North American marine biological invasions (solid line, data starting in the 1800s with a general upward trend; Ruiz et al., 2000), global marine wild fish harvest (solid line, data starting in the 1950s with a general upward trend; Food Agricultural Organization [FAO] U.N., 2010), cumulative seagrass loss (dotted line, data starting around the mid 1920's with a general upward trend and a sharp increase after the mid 1970s; Waycott et al., 2009), cumulative Caribbean coral cover loss (dotted line, data starting around the mid 1970s with a general upward trend; Gardner et al., 2003), cumulative mangrove loss (dotted line, data starting around the mid 1920's with a general upward trend and a sharp increase after the mid 1970s; FAO U.N., 2007), cumulative global hypoxic zones (dotted line, data starting in the early 1900's with a general upward trend; Diaz and Rosenberg, 2008), and global mariculture production (dotted line, data starting around 1950 with an upward trend; FAO U.N., 2010). All time series in (b) are normalized to 1980 levels. Trends with <1.5-fold variation are depicted as solid lines (left axis), and trends with >1.5-fold variation are depicted as dotted lines (right axis) (Source: Doney et al., 2012).

Figure 1-3 Imapcts of Climate Change on Marine Ecosystems. This table is intended to provide illustrative examples of how climate change is currently affecting U.S. ecosystems, the species they support, and the resulting impacts on ocean services. It is not intended to be comprehensive or to provide any ranking or prioritization. Black arrows represent impacts driven by climate change either directly or indirectly. Gray arrows represent countering effects of various adaptation efforts. ↑ indicates where climate change is predicted to increase the incidence or magnitude of that attribute and Δ indicates attributes where the impact of climate change on that attribute is variable.

This assessment is organized into the following major Sections:

• Sections 2-4 assess the state of knowledge on the impacts and vulnerabilities of ocean physical and chemical conditions (Section 2), biological systems (Section 3), and ocean uses and services (Section 4) in a changing climate.

• Section 5 assesses the international implications of these climate impacts and vulnerabilities because U.S. oceans and marine resources are inherently connected to ocean areas beyond U.S. borders.

• Section 6 assesses the status of efforts to prepare for and adapt to the impacts of climate change on U.S. oceans and marine resources.

• Section 7 identifies key steps to sustain and advance assessment of climate impacts on U.S. oceans and marine resources

1.2 Linkages with Other Parts of the National Climate Assessment

U.S marine ecosystems are inherently connected to U.S. coastal and terrestrial areas through many important linkages including the:

• Flow of water, organic matter, and sediments from land to sea;

• Effect of oceans on the physical climate system, including water, wind, and heat energy;

• Connectivity and movement of species; and

• Extensive and diverse uses of marine resources and services that occur throughout the Nation.

This means that climate impacts on ocean ecosystems intersect with, and have major implications for, many regions and sectors across the nation that are also considered in the NCA. As part of larger marine ecosystems and global oceans, U.S. marine ecosystems influence and are strongly influenced by ocean conditions beyond U.S. jurisdiction. This means that changes in these systems can have implications for U.S. efforts internationally.

The following is a brief summary of some of the key intersections with other parts of the NCA:

• Regional Assessments: Seven of the eight regions of the NCA include coastal areas and marine ecosystems. Climate change impacts on marine ecosystems may have significant implications in these regions especially for marine-dependent species, habitats, users, and communities;

• Coastal Areas: The oceans and marine resources considered in this report are directly tied to species, processes, and services of the coastal zone. Climate change impacts on marine ecosystems have significant implications for coastal areas, especially for marine-dependent species, habitats, users, and communities;

• Public Health: Marine ecosystem conditions can directly impact public health through harmful algal blooms, contaminated seafood, the spread of disease, and other mechanisms. Climate change impacts that increase these conditions in marine ecosystems could have significant implications, especially in coastal areas;

• Transportation: Marine transportation is critical to the nation’s economy, health, and safety, as well as national security. Climate change impacts on marine ecosystems, such as changes in ocean circulation, storms, and other features, could have significant implications for the nation’s vital marine transportation system;

• Energy Supply: The nation’s energy supply from marine-related sources is increasing and may grow as the nation seeks alternative sources of energy. Climate change impacts on marine ecosystems, such as changes in ocean circulation, storms, and other features, could have significant implications for the ocean energy sector; and

• Ecosystems and ...

Table of contents

• Cover
• Copyright
• Title Page
• Acknowledgements
• Contents
• Key Terms
• Acronyms
• Communicating Uncertainty
• Executive Summary
• chapter 1: Introduction
• chapter 2: Climate-Driven Physical and Chemical Changes in Marine Ecosystems
• chapter 3: Impacts of Climate Change on Marine Organisms
• Chapter 4: Impacts of Climate Change on Human Uses of the Ocean and Ocean Services
• Chapter 5: International Implications of Climate Change
• Chapter 6: Ocean Management Challenges, Adaptation Approaches, and Opportunities in a Changing Climate
• chapter 7: Sustaining the Assessment of Climate Impacts on Oceans and Marine Resources
• Appendix A: Status of and Climate Change Impacts to Commercial, Recreational, and Subsistence Fisheries in the U.S.
• References