Prepared for the 2013 National Climate Assessmand 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 assessmof scientific knowledge of the currand 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 assessmof 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 ManagemChallenges, Adaptation Approaches, and Opportunities in a Changing Climate
· Sustaining the Assessmof 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.
About the Author
Dr. Howard is a AAAS Science and Technology Policy Fellow for the National Oceanic and Atmospheric Administration’s (NOAA) National Marine Fisheries Service. In her currposition, Jennifer co-lead and coordinated the developmof the Ocean and Marine Resources in a Changing Climate Technical Input Report to the National Climate Assessmand coordinates the Interagency Working Group for Ocean Acidification. Before starting her fellowship at NOAA, Jennifer was conducting her postdoctoral research at the University of Maryland. Her research focused on environmental contaminants found in wastewater and agricultural runoff, specifically endocrine disrupting chemicals, and their effect on aquatic wildlife reproduction and development. Jennifer received her PhD from Texas A&M in reproductive physiology and completed the Heller Research Fellowship in the Endocrinology Departmat the San Diego Zoo’s Institute for Conservation Research. She has a broad range of scientific interests, mof which center around wildlife and habitat conservation, biodiversity conservation, and climate change.
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Oceans and Marine Resources in a Changing Climate
A Technical Input to the 2013 National Climate Assessment
By Roger Griffis, Jennifer Howard
ISLAND PRESSCopyright © 2013 The National Oceanic and Atmospheric Administration
All rights reserved.
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.
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.
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 Biodiversity: Marine ecosystems are some of the nation's most complex, biologically rich, and valued ecosystems. Climate change is already impacting marine ecosystems and biodiversity and these impacts are expected to increase with significant implications for communities and economies dependent on marine resources.CHAPTER 2
Climate-Driven Physical and Chemical Changes in Marine Ecosystems
The Earth's oceans are gradually warming as a direct result of increasing atmospheric carbon dioxide and other greenhouse gasses. The Intergovernmental Panel on Climate Change (IPCC) reported that, between 1961 and 2003, the average temperature of the upper 700 meters of water increased by 0.2° Celsius (IPCC, 2007a). Average global land and sea surface temperatures are continually increasing; 2010's temperatures were the hottest on record (Blunden et al., 2011). Warming of the Earth's oceans has multiple consequences, including sea level rise, changes in global climate patterns, increased stratification of the water column, and changes in ocean circulation and salinity. In addition to warming the oceans, CO2 is being absorbed by the oceans, causing a series of chemical reactions that lead to a reduction in ocean pH.
Arctic sea ice volume has shrunk by 75% over the last decade (Laxton et al. 2013); incidences of hypoxia (regions where the oxygen concentration has been depleted) within U.S. estuaries have increased thirty-fold since 1960 (Diaz and Rosenberg, 2008); and ocean acidity has increased by 30 percent over the past century (Feely et al., 2004). Warming of ocean waters increases the available energy used to create short-lived storms, and while the frequency of hurricanes and typhoons may not change, a warming ocean will likely result in increased storm intensity (Knutson et al., 2010). As the ocean surface warms, stratification increases, resulting in the warmer water remaining at the surface instead of mixing with the cooler water below. Warm water is not as efficient at absorbing CO2, and while this might have a slowing effect on ocean acidification, consequences include potential reductions in the uptake of atmospheric CO2 by the oceans. While there is some variability in salinity levels globally, recent analyses of water density and atmospheric data collected from 1970-2005 suggests that there are overriding changes, including acceleration, in the global hydrological cycle (Helm 2010).
Some evidence suggests that warming oceans affect salinity, circulation patterns, and climate regimes, but uncertainty remains. Many climate regimes follow oscillation patterns that can take place over time periods lasting between several years to decades, which can make it difficult to tease apart natural patterns and variability from anthropogenic climate change. A great deal of uncertainty remains about how rapidly the physical and chemical attributes of the oceans will change in the future, as well as the magnitude of specific impacts and what, if any, potential feedbacks will occur.
The physical and chemical changes taking place in the global oceans set the stage for subsequent effects on marine organisms (Section 3), U.S. communities and economies dependent on marine services (Section 4), U.S. governance and interactions with neighboring countries (Section 5), and potential adaptation strategies (Section 6).
1. The Earth's oceans are warming as a result of increasing concentrations of atmospheric carbon dioxide and other greenhouse gases.
From 1955 to 2008, approximately 84 percent of the added heat from climate change has been absorbed by the oceans, thereby increasing the average temperature of the upper 700 meters of water by 0.2° Celsius; this trend is likely to continue.
Rising global temperatures are likely to cause greater oceanic evaporation of water vapor, which is a potent greenhouse gas, into the atmosphere, thus amplifying warming due to climate change.
2. Arctic ice has been decreasing in extent since the second half of the 20th century as a result of oceanic and atmospheric warming.
Arctic ice has been decreasing throughout the early 20th century. The summer of 2012 saw a record low, when sea ice extent shrank to 3.6 million km2, approximately 1 million km2 less than the previous minima of 2007. Arctic sea ice volume has decreased by 75% over the previous decade.
The most significant consequence of melting Arctic ice will be sea level rise. A growing body of recently published work suggests that accelerating loss of the great polar ice sheets in Greenland and Antarctica will likely result in global mean sea level rise of more than 1 meter above present day sea level by 2100.
Reductions in ice may occur more rapidly than previously suggested by coupled air- sea-ice climate models. These models may have overestimated ice thickness; more recent modeling predicts that a seasonal ice-free state could occur as early as 2030.
3. The oceans play an important role in climate regulation through the uptake and sequestration of anthropogenic CO2.
The annual accumulation of atmospheric CO2 has been increasing and in 2010 the overall CO2 concentration was 39 percent above the concentration at the start of the Industrial Revolution in 1750.
Ocean water holds approximately 50 times more CO2 than the atmosphere and holds the majority of that in the deeper, colder waters; however, the ability of oceans to absorb CO2decreases with increasing temperature and decreasing pH.
Healthy coastal wetlands are effective at storing and sequestering carbon. This carbon is referred to as "coastal blue carbon." Unfortunately, our nation has lost more than half of its wetlands in the past 200 years.
4. The oceans absorb carbon dioxide, causing a series of chemical reactions that reduce ocean pH, a process known as ocean acidification.
Over the past century, the average ocean pH has decreased by 30 percent; however, in coastal areas this number may be much higher following upwelling events.
Predictions indicate that ocean acidification will lead to an under-saturation of argonite in ocean surface waters by the year 2050. Argonite is a form of calcium carbonate impacted by the ocean acidification process and a key component of the exoskeleton of corals and some plankton.
Polar ecosystems may experience exacerbated ocean acidification because CO2 is more soluble in colder water and therefore more likely to be absorbed.
5. Ocean temperature and precipitation/evaporation rates have a direct influence on the Earth's weather and precipitation patterns that will likely increase storm intensity but decrease (or have no effect on) storm frequency.
Climate change impacts on winds may be moderate and vary regionally but precipitation events are predicted to become more intense.
Shifts in precipitation patterns from snow to rain are likely, resulting in decreased snow pack and earlier snow melts that may impact water availability.
Storm intensity is likely to increase and could have a large impact, especially on coastal communities because of the increases in coastal populations and infrastructure expected over the next century. The impact of storm surges will be greater for the same reasons as well as the expected rise in sea level.
6. Given that climate and oceans interact to produce intra- and inter-decadal variability in ocean currents, upwelling, and basin-scale circulation, climate change will likely influence these important ocean features, although the ability to detect and project such impacts is low.
Melting of polar ice will reduce the salinity and thus density of polar waters, which could weaken the rate at which this water sinks, possibly impairing circulation.
However, uncertainty remains about the quantity of freshwater input necessary to slow ocean currents like the Thermohaline Circulation.
Key Science Gaps/Knowledge Needs
Many critical research gaps related to impacts of climate change on physical and chemical ocean systems remain, including:
Improved understanding of and model projection for thermal expansion of the oceans and associated sea level rise;
Improved projections for Arctic ice melt and the associated impacts on the oceans' currents and stratification;
Advanced integration of observations and predictive modeling, particularly at regional scales, in order to gain insight into future impacts of climate change;
Determination of how changes in upper ocean temperature distributions impact the atmosphere;
Successful monitoring of tropical cyclone activity globally for emergence of trends, as well as further research concerning earlier detection and/or anticipation of future storms; and
Improved understanding of the role of "blue carbon" science in ecosystem management issues and what its implications mean for future climate adaptation strategies as well as coastal habitat conservation.
Excerpted from Oceans and Marine Resources in a Changing Climate by Roger Griffis, Jennifer Howard. Copyright © 2013 The National Oceanic and Atmospheric Administration. Excerpted by permission of ISLAND PRESS.
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Table of Contents
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.,