Rising atmospheric carbon dioxide (CO2), primarily from human fossil fuel combustion, reduces ocean pH and causes wholesale shifts in seawater carbonate chemistry. The process of ocean acidification is well documented in field data, and the rate will accelerate over this century unless future CO2 emissions are curbed dramatically. Acidification alters seawater chemical speciation and biogeochemical cycles of many elements and compounds. One well-known effect is the lowering of calcium carbonate saturation states, which impacts shell-forming marine organisms from plankton to benthic molluscs, echinoderms, and corals. Many calcifying species exhibit reduced calcification and growth rates in laboratory experiments under high-CO2 conditions. Ocean acidification also causes an increase in carbon fixation rates in some photosynthetic organisms (both calcifying and noncalcifying). The potential for marine organisms to adapt to increasing CO2 and broader implications for ocean ecosystems are not well known; both are high priorities for future research. Although ocean pH has varied in the geological past, paleo-events may be only imperfect analogs to current conditions. INTRODUCTION .................................................................... 213 OCEAN CARBONATE SYSTEM ............................................ 217 BIOLOGICAL RESPONSES TO ACIDIFICATION ............... 219 Shallow-Water Tropical Corals and Coral Reefs ........... 220 Deep-Water Corals and Carbonate Mounds.................. 223 Other Benthic Invertebrates ......................................... 224  Reproduced with permission from the Annual Review of Marine Science, Volume 1 © 2009 by Annual Reviews, http://www.annualreviews.org, Annu. Rev. Mar. Sci. 2009. 1:169–92. First published online as a Review in Advance on August 29, 2009. This article’s doi: 10.1146/annurev.marine.010908.163834.  Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543; email: sdoney@whoi.edu  Department of Biological Sciences, California State University, San Marcos, California 92096; email: fabry@csusm.edu † Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, Washington 98115; email: Richard.A.Feely@noaa.gov  Institute for the Study of Society and Environment, National Center for Atmospheric Research, Boulder, Colorado 80307; email: kleypas@ucar.edu 1 Doney et al.: Ocean Acidification: The Other CO2 Problem? Published by UW Law Digital Commons, 2019 2016] OCEAN ACIDIFICATION: THE OTHER CO2 PROBLEM 213 Planktonic Calcification ................................................. 225 Primary Production and Nitrogen Fixation .................. 226 ECOLOGICAL AND BIOGEOCHEMICAL IMPACTS .......... 228 Food Webs and Ecosystems ........................................... 228 Oceanic CaCO3 Budget .................................................. 229 Carbon and Nutrient Cycling ........................................ 231 Chemical Speciation in Seawater .................................. 232 GEOLOGICAL AND HISTORICAL EVIDENCE ................... 233 DISCLOSURE STATEMENT ................................................. 237 ACKNOWLEDGMENTS ......................................................... 238 LITERATURE CITED ............................................................. 238 INTRODUCTION Over the past 250 years, atmospheric carbon dioxide (CO2) levels increased by nearly 40%, from preindustrial levels of approximately 280 ppmv (parts per million volume) to nearly 384 ppmv in 2007 (Solomon et al. 2007). This rate of increase, driven by human fossil fuel combustion and deforestation, is at least an order of magnitude faster than has occurred for millions of years (Doney & Schimel 2007), and the current concentration is higher than experienced on Earth for at least the past 800,000 years (Lüthi et al. 2008). Rising atmospheric CO2 is tempered by oceanic uptake, which accounts for nearly a third of anthropogenic carbon added to the atmosphere (Sabine & Feely 2007, Sabine et al. 2004), and without which atmospheric CO2 would be approximately 450 ppmv today, a level of CO2 that would have led to even greater climate change than witnessed today. Ocean CO2 uptake, however, is not benign; it causes pH1 reductions and alterations in fundamental chemical balances that together are commonly referred to as ocean acidification. Because climate change and ocean acidification are both caused by increasing atmospheric CO2, acidification is commonly referred to as the “other CO2 problem” (Henderson 2006, Turley 2005). Ocean acidification2 is a predictable consequence of rising atmospheric CO2 and does not suffer from uncertainties associated with climate change forecasts. Absorption of anthropogenic CO2, reduced pH, and lower calcium carbonate 1. pH: a measure of ocean acidity and hydrogen ion H+ concentration; pH 

Increasing atmospheric concentrations of methane have led scientists to examine its sources of origin. Ruminant livestock can produce 250 to 500 L of methane per day. This level of production results in estimates of the contribution by cattle to global warming that may occur in the next 50 to 100 yr to be a little less than 2%. Many factors influence methane emissions from cattle and include the following: level of feed intake, type of carbohydrate in the diet, feed processing, addition of lipids or ionophores t o the diet, and alterations in the ruminal microflora. Manipulation of these factors can reduce methane emissions from cattle. Many techniques exist to quantify methane emissions from individual or groups of animals. Enclosure techniques are precise but require trained animals and may limit animal movement. Isotopic and nonisotopic tracer techniques may also be used effectively. Prediction equations based on fermentation balance or feed characteristics have been used to estimate methane production. These equations are useful, but the assumptions and conditions that must be met for each equation limit their ability to accurately predict methane production. Methane production from groups of animals can be measured by mass balance, micrometeorological, or tracer methods. These techniques can measure methane emissions from animals in either indoor or outdoor enclosures. Use of these techniques and knowledge of the factors that impact methane production can result in the development of mitigation strategies to reduce methane losses by cattle. Implementation of these strategies should result in enhanced animal productivity and decreased contributions by cattle to the atmospheric methane budget.

Ocean acidification is an undisputed fact. The ocean presently takes up one-fourth of the carbon CO2 emitted to the atmosphere from human activities. As this CO2 dissolves in the surface ocean, it reacts with seawater to form carbonic acid, increasing ocean acidity and shifting the partitioning of inorganic carbon species towards increased CO2 and dissolved inorganic carbon, and decreased concentration of carbonate ion. While our understanding of the possible consequences of ocean acidification is still rudimentary, both the scientific community and the society at large are increasingly concerned about the possible risks associated with ocean acidification for marine organisms and ecosystems. As this new and pressing field of marine research gains momentum, many in our community, including representatives of coordinated research projects, international scientific organisations, funding agencies, and scientists in this field felt the need to provide guidelines and standards for ocean acidification research. To initiate this process, the European Project on Ocean Acidification (EPOCA) and the International Oceanographic Commission (IOC) jointly invited over 40 leading scientists active in ocean acidification research to a meeting at the Leibniz Institute of Marine Science (IFM-GEOMAR) in Kiel, Germany on 19-21 November 2008. At the meeting, which was sponsored by EPOCA, IOC, the Scientific Council on Oceanic Research (SCOR), the U.S. Ocean Carbon and Biogeochemistry Project (OCB) and the Kiel Excellence Cluster “The Future Ocean”, the basic structure and contents of the guide was agreed upon and an outline was drafted. In the following months, the workshop participants and additional invited experts prepared draft manuscripts for each of the sections, which were subsequently reviewed by independent experts and revised according to their recommendations. Starting 15 May 2009, the guide was made publicly available for an open community review.

An altered balance between Th1 and Th2 cytokines is responsible for a variety of immunoinflammatory disorders such as asthma, yet the role of posttranscriptional mechanisms, such as those mediated by microRNAs (miRs), in adjusting the relative magnitude and balance of Th cytokine expression have been largely unexplored. In this study, we show that miR-21 has a central role in setting a balance between Th1 and Th2 responses to Ags. Targeted ablation of miR-21 in mice led to reduced lung eosinophilia after allergen challenge, with a broadly reprogrammed immunoactivation transcriptome and significantly increased levels of the Th1 cytokine IFN-γ. Biological network-based transcriptome analysis of OVA-challenged miR-21−/− mice identified an unexpected prominent dysregulation of IL-12/IFN-γ pathways as the most significantly affected in the lungs, with a key role for miR-21 in IFN-γ signaling and T cell polarization, consistent with a functional miR-21 binding site in IL-12p35. In support of these hypotheses, miR-21 deficiency led dendritic cells to produce more IL-12 after LPS stimulation and OVA-challenged CD4+ T lymphocytes to produce increased IFN-γ and decreased IL-4. Further, loss of miR-21 significantly enhanced the Th1-associated delayed-type hypersensitivity cutaneous responses. Thus, our results define miR-21 as a major regulator of Th1 versus Th2 responses, defining a new mechanism for regulating polarized immunoinflammatory responses.

The increase in atmospheric carbon dioxide (CO2), originating largely from human fossil fuel combustion and deforestation since the beginning of the industrial era, is causing a decrease in ocean pH and changes to seawater carbonate chemistry. This process, termed ocean acidification, is now well established from modeling and field data, and the rate of change in ocean pH and carbon chemistry is expected to increase significantly over this century unless future CO2 emissions are restricted dramatically. The rate of CO2 increase is the fastest the Earth has experienced in 65 million years (Ridgwell and Schmidt, 2010), and the current concentration is estimated to be the highest in, at least, the past 50 million years (Zachos et al., 2008). Central to predicting the atmospheric carbon inventory during the 21st century will be understanding and predicting the adjustments in the ocean uptake and exchange of both anthropogenic and natural CO2. To quantify these changes on a global scale, an international interdisciplinary program of ship-based hydrography, time-series moorings, floats and gliders with carbon, pH and oxygen sensors, and ecological surveys is already underway. This program together with implementations of molecular technology will help scientists determine the extent of the large-scale changes in the carbon chemistry of seawater and the associated biological responses to ocean acidification in both open ocean and coastal environments. Indeed many countries are presently engaged in ocean acidification research and monitoring activities. Some examples include the European Union (EPOCA, EuroSITES, MEECE), German (BIOACID), UK (UK Ocean Acidification Research Programme), US (emerging program supported by NSF, NOAA, NASA, USGS) and Japan (programs supported by MoE and MEXT) ocean acidification research programmes. The proposed activities will require a coordinated international research effort that is closely linked with international carbon research programs, such as the CLIVAR/CO2 Repeat Hydrography (GO-SHIP) Program, the Integrated Ocean Drilling Program, and the IGBP programmes SOLAS and IMBER. The Global Ocean Acidification Observation Network will interface strongly with the data synthesis, archiving and management activities of existing international ocean acidification programs.

Carbon dioxide (CO2) in the atmosphere is absorbed at the ocean surface by reacting with seawater to form a weak, naturally occurring acid called carbonic acid. As atmospheric carbon dioxide increases, the concentration of carbonic acid in seawater also increases, causing a decrease in ocean pH and carbonate mineral saturation states, a process known as ocean acidification. The oceans have absorbed approximately 525 billion tons of carbon dioxide from the atmosphere, or about one-quarter to one-third of the anthropogenic carbon emissions released since the beginning of the Industrial Revolution. Global surveys of ocean chemistry have revealed that seawater pH has decreased by about 0.1 units (from a pH of 8.2 to 8.1) since the 1700s due to absorption of carbon dioxide (Raven and others, 2005). Modeling studies, based on Intergovernmental Panel on Climate Change (IPCC) CO2 emission scenarios, predict that atmospheric carbon dioxide levels could reach more than 500 parts per million (ppm) by the middle of this century and 800 ppm by the year 2100, causing an additional decrease in surface water pH of 0.3 pH units. Ocean acidification is a global threat and is already having profound and deleterious effects on the geology, biology, chemistry, and socioeconomic resources of coastal and marine habitats. The polar and sub-polar seas have been identified as the bellwethers for global ocean acidification.

Owing to anthropogenic-induced acidification, surface waters of the high latitudes are projected to become persistently undersaturated with respect to aragonite as early as mid-century. Seasonal aragonite undersaturation in surface and shallow subsurface waters of some northern polar seas has already been observed. Calcified marine organisms, including thecosomatous pteropods, foraminifers, cold-water corals, sea urchins, molluscs, and coralline algae, make up significant components of the rich communities in high latitudes, and they are thought to be at risk with increasing ocean acidification. Over the next decades, trends of rising temperatures and species invasions coupled with progressive ocean acidification are expected to increasingly influence both planktonic and benthic marine communities of Antarctica and the Arctic. The rate and magnitude of these changes underscore the urgent need for increased efforts in ocean acidity research and monitoring in polar and subpolar seas.

Rising atmospheric carbon dioxide (CO2), primarily from human fossil fuel combustion, reduces ocean pH and causes wholesale shifts in seawater carbonate chemistry. The process of ocean acidification is well documented in field data, and the rate will accelerate over this century unless future CO2emissions are curbed dramatically. Acidification alters seawater chemical speciation and biogeochemical cycles of many elements and compounds. One well-known effect is the lowering of calcium carbonate saturation states, which impacts shell-forming marine organisms from plankton to benthic molluscs, echinoderms, and corals. Many calcifying species exhibit reduced calcification and growth rates in laboratory experiments under high-CO2conditions. Ocean acidification also causes an increase in carbon fixation rates in some photosynthetic organisms (both calcifying and noncalcifying). The potential for marine organisms to adapt to increasing CO2and broader implications for ocean ecosystems are not well known; both are high priorities for future research. Although ocean pH has varied in the geological past, paleo-events may be only imperfect analogs to current conditions.

The first symposium on “The Ocean in a High-CO2 World” in 2004 proved to be a landmark event in our understanding of the seriousness of ocean acidification, as reported in Oceanography (Cicerone et al., 2004). The scientific community reunited in 2008 for a second symposium on “The Ocean in a High-CO2 World.” During the four years between the two symposia, more scientific papers were published on the topic of ocean acidification than during the preceding 55 years. Ocean acidification is now widely cited in the press and is familiar to many nonscientists. Participants at the 2008 symposium identified new research priorities and stressed the importance of improving international coordination to facilitate agreements on protocols, methods, and data reporting in order to optimize limited resources by greater sharing of materials, facilities, expertise, and data. Despite major uncertainties, the research community must find ways to scale up understanding of individual organisms’ responses to provide meaningful predictions of ocean acidification’s effects on food webs, fisheries, marine ecosystems, coastal erosion, and tourism. Easy-to-understand information, such as simple indicators of change and of thresholds beyond which marine ecosystems will not recover, is also needed for management and policymaking.

Over a period of less than a decade, ocean acidification-the change in seawater chemistry due to rising atmospheric carbon dioxide (CO2) levels and subsequent impacts on marine life-has become one of the most critical and pressing issues facing the ocean research community and marine resource managers alike. The objective of this special issue of Oceanography is to provide an overview of the current scientific understanding of ocean acidification as well as to indicate the substantial gaps in our present knowledge. Papers in the special issue discuss the past, current, and future trends in seawater chemistry; highlight potential vulnerabilities to marine species, ecosystems, and marine resources to elevated CO2; and outline a roadmap toward future research directions. In this introductory article, we present a brief introduction on ocean acidification and some historical context for how it emerged so quickly and recently as a key research topic.

Anthropogenic pressures on the Earth System have reached a scale where abrupt global environmental change can no longer be excluded. We propose a new approach to global sustainability in which we define planetary boundaries within which we expect that humanity can operate safely. Transgressing one or more planetary boundaries may be deleterious or even catastrophic due to the risk of crossing thresholds that will trigger non-linear, abrupt environmental change within continental- to planetary-scale systems. We have identified nine planetary boundaries and, drawing upon current scientific understanding, we propose quantifications for seven of them. These seven are climate change (CO2 concentration in the atmosphere <350 ppm and/or a maximum change of +1 W m-2 in radiative forcing); ocean acidification (mean surface seawater saturation state with respect to aragonite ≥ 80% of pre-industrial levels); stratospheric ozone (<5% reduction in O3 concentration from pre-industrial level of 290 Dobson Units); biogeochemical nitrogen (N) cycle (limit industrial and agricultural fixation of N2 to 35 Tg N yr-1) and phosphorus (P) cycle (annual P inflow to oceans not to exceed 10 times the natural background weathering of P); global freshwater use (<4000 km3 yr-1 of consumptive use of runoff resources); land system change (<15% of the ice-free land surface under cropland); and the rate at which biological diversity is lost (annual rate of <10 extinctions per million species). The two additional planetary boundaries for which we have not yet been able to determine a boundary level are chemical pollution and atmospheric aerosol loading. We estimate that humanity has already transgressed three planetary boundaries: for climate change, rate of biodiversity loss, and changes to the global nitrogen cycle. Planetary boundaries are interdependent, because transgressing one may both shift the position of other boundaries or cause them to be transgressed. The social impacts of transgressing boundaries will be a function of the social-ecological resilience of the affected societies. Our proposed boundaries are rough, first estimates only, surrounded by large uncertainties and knowledge gaps. Filling these gaps will require major advancements in Earth System and resilience science. The proposed concept of "planetary boundaries" lays the groundwork for shifting our approach to governance and management, away from the essentially sectoral analyses of limits to growth aimed at minimizing negative externalities, toward the estimation of the safe space for human development. Planetary boundaries define, as it were, the boundaries of the "planetary playing field" for humanity if we want to be sure of avoiding major human-induced environmental change on a global scale.

Identifying and quantifying planetary boundaries that must not be transgressed could help prevent human activities from causing unacceptable environmental change, argue Johan Rockström and colleagues.

The oceanic uptake of anthropogenic CO2 changes the seawater chemistry and potentially can alter biological systems in the upper oceans. Estimates of future atmospheric and oceanic CO2 concentrations, based on the Intergovernmental Panel on Climate Change (IPCC) emission scenarios, indicate that atmospheric CO2 levels could approach 800 ppm by the end of the century. Corresponding models for the oceans indicate that surface water pH would decrease by approximately 0.4 pH units, and the carbonate ion concentration would decrease by as much as 48% by the end of the century. The surface ocean pH would be lower than it has been for more than 20 million years. Such changes would significantly lower the ocean's buffering capacity, which would reduce its ability to accept more CO2 from the atmosphere. Recent field and laboratory studies reveal that the carbonate chemistry of seawater has a profound impact on the calcification rates of individual species and communities in both planktonic and benthic habitats. The calcification rates of nearly all calcifying organisms studied to date decrease in response to decreased carbonate ion concentration. In general, when pCO(2) was increased to twice preindustrial levels, a decrease in the calcification rate ranging from about -5% to -60% was observed. Unless calcifying organisms can adapt to projected changes in seawater chemistry, there will likely be profound changes in the structure of pelagic and benthic marine ecosystems.

This special issue of The Cancer Journal originated in Lyon, France, November 17 to 19, 2008. This was the 6th Biannual Meeting of the Peritoneal Surface Oncology Group International. The topics for presentation and their authorship were chosen by Olivier Glehen and myself at that time. It was most appropriate that the biannual meeting in 2008 would be held in France. With the French-speaking consortium that has been engineered Dominique Elias, Francois Gilly, and Olivier Glehen, an effort to optimally manage peritoneal surface malignancy within France has occurred over the last decade that, in my opinion, has reached epic proportion. The French group has published their own monograph, “Monographies de L’association Francaise de Chirurgie” to summarize their accomplishments.1 Not only has laboratory and clinical research excelled within this French-speaking group but also benefits to patients have been forthcoming. In France, the treatment of colorectal and appendiceal dissemination of cancer to the peritoneal surfaces is treated using cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC) as a standard of care fully funded by the French Health Care System. Not just some but all French people have these treatment modalities available to them. Congratulations to the efforts of Gilly, Glehen, and Elias! The first meeting of the Peritoneal Surface Oncology Group International was a humble one that occurred in London at The Royal College of Surgeons in 1998. Professor Bill Heald and myself organized this international effort to share thoughts on the prevention and treatment of peritoneal dissemination of gastrointestinal cancer. Approximately 30 speakers and participants were there to enter into the presentations and discussions. Since then, the biannual meeting has become more popular. Figure 1 shows the gradual progression of the interest in peritoneal surface oncology from 1998 through 2008. Over these 10 years, a profound change in the attitudes of oncologists toward peritoneal dissemination of colorectal and appendiceal cancer has occurred. The next meeting will be in Uppsala, Sweden on September 8 to 10, 2010. The fact that CRS plus HIPEC has reached the level of “standard of care” supported by national guidelines is also presented in the manuscript by Vic J. Verwaal. He presents the long-term experience in the management of colorectal carcinomatosis that started at the Netherlands Cancer Institute under the direction of Frans Zoetmulder and now continues throughout Holland carefully shepherded along by Vic J. Verwaal. The commitment to an optimized nationwide program in the management of carcinomatosis available to all Dutch people is clearly evident in the presentation of Dr. Verwaal. The program in Spain, Italy, Belgium, Germany, and Scandinavia is strong and rapidly progressing. Perhaps, at this point in time not as well organized as in France and the Netherlands but nevertheless growing on a regular basis. In the United States, the efforts to develop centers of excellence for the management of peritoneal carcinomatosis have continued to prosper. Pittsburgh, Pennsylvania, Washington, DC, Winston-Salem, North Carolina, Omaha, Nebraska, and Houston, Texas have established centers with experienced surgeons directing the programs. The interest in medical oncologists in referral of colorectal and appendiceal cancer patients with carcinomatosis has increased substantially. The realization that evidence-based medicine supports CRS and HIPEC for carcinomatosis, and that systemic chemotherapy using FOLFOX and Avastin cannot be supported by the literature has led to this “cytoreduction reversal.” The wonderful article in the Journal of Clinical Oncology by Sanoff et al2 clearly shows the benefits of oxaliplatin-based chemotherapy for colorectal cancer patients who have objective evidence of their metastatic disease. Unfortunately, with carcinomatosis, there

Ocean acidification (OA) is increasingly recognized as an additional effect of rising carbon dioxide (CO2) levels. To study this, a workshop, funded by the European Science Foundation EuroCLIMATE Programme and the Past Global Changes (PAGES) project, brought together a range of experts to review knowledge of the likely effects of OA on planktonic calcifying organisms and marine biogeochemistry in the upper ocean and to prioritize research for the near future.The 45 participants reviewed research on four core‐topic sessions: (1) Biocalcification mechanisms and their vulnerability to OA; (2) Genetics and physiology: Investigating organismal responses to OA; (3) Ecology and biogeography: Predicting the effects of population responses to OA; and (4) Lessons from the fossil record: Past responses to OA. Results and discussion will be published; a detailed report is available at http://www.esf.org/acidification‐workshop/venue.html and http://the‐eggs.org/articles.php?id=112.