Impacts on coastal environments from an acidifying ocean can be reduced by implementing local and regional pollution-reduction measures. Wolcott Henry 2005/Marine Photobank
A new report in Science looks at how local and state governments can better protect their coastal environments by reducing local and regional contributors to ocean acidification. While ocean acidification is a global problem, the result of rising concentrations of carbon dioxide (CO²), levels of acidification can vary locally as a result of both natural and man-made conditions. Freshwater input via rivers, pollution from a range of sources and soil erosion can significantly add to the acidification of coastal areas note Ryan Kelly of the Center for Ocean Solutions at Stanford University and colleagues. Furthermore, they point out, the impacts of acidification on various species and overall foodwebs are likely amplified by the host of other stressors affecting coastal regions, such as overfishing, loss of habitat, temperature increases associated with climate change and nonacidifying pollution.
In the absence of large-scale and comprehensive carbon dioxide emission controls, Kelly and cowriters argue that “local and state governments have both the authority and motive to address many stressors that drive or exacerbate acidification conditions.” They then consider the different legal mechanisms and management strategies that could be employed within the U.S., though, as they point out, similar tools are available in other countries.
The first approach uses state authority as directed by the Clean Water Act to monitor, maintain and restore ecosystem health. Federal funding is often available to support local governments in preventing stormwater surges, improving water treatment facilities and protecting and restoring wetlands, all effective measures in reducing acidification-related runoff. Second, the authors suggest enhancing efforts to reduce coastal erosion: this not only safeguards the integrity of the coastline but also reduces sediment and nutrient runoff that may contain acidification-inducing fertilizers. Local efforts could be regionally coordinated, for example, to promote vegetation growth throughout watersheds as an effective measure against erosion. Third, local and regional land-use regulations could reduce vehicle emissions and runoff while state control over zoning could integrate potential outcomes for acidification into the overall planning process. Lastly, enforcement of federal emissions requirements for such industrial pollutants as nitrogen oxide and sulfur oxide should provide local benefits given these pollutants’ short atmospheric resident times.
The authors state that the implementation of “smaller-scale actions … runs contrary to the widely held perception that acidification cannot be addressed at the scale of local (e.g., municipal and county) or regional (state, multistate, and territorial) jurisdictions.” This, they conclude, is simply a result of “low awareness and a sense that the causes are globally diffuse.”
For additional information on ocean acidification read the blog post on BigThink.com.
Source: Kelly, R.P. et al. 2011. Mitigating local causes of ocean acidification with existing laws. Science 332(6033): 1036-1037.
Contact: Ryan Kelly, Stanford University. E-mail: firstname.lastname@example.org
Climate change mitigation and proactive coastal protection will likely both be needed to prevent the displacement of many millions of people from rising sea levels. Jashim Salam/Marine Photobank
As the prospects of immediate climate mitigation appear to be diminishing, various researchers have begun contemplating adaptation scenarios that may be required for a global mean temperature rise of 4 degrees Celsius (7.2 degrees Fahrenheit) or more relative to 1980-1999. One area of increasing concern is the potential magnitude and impacts of sea-level rise, particularly as many millions of people live in coastal areas, and populations along coasts are growing faster than the global average. Especially vulnerable to small rises are populated deltaic regions and many coastal cities and, should sea-level rise by around one meter (3.3 feet), many island nation-states.
But by how much could sea-level rise by the end of the twenty-first century if global temperatures increase by more than 4 degrees C? And what are the chances that proactive adaptation measures – such as coastal protection or planned retreat – will be implemented so as to substantially reduce the numbers of people potentially faced with forced migration? These are some of the questions looked at by Robert J. Nicholls of the University of Southampton in the United Kingdom and colleagues in a recent paper published in Philosophical Transactions of the Royal Society A.
The upper limit to sea-level rise during this century as determined by the Intergovernmental Panel on Climate Change (IPCC) in its Fourth Assessment Report (AR4) released in 2007 was placed at between 61 and 76 centimeters (2 to 2.5 feet). However, as Nicholls and co-authors point out, the IPCC noted in an often overlooked statement that the “understanding of some important effects driving sea level rise is too limited . . . [to] provide a best estimate or an upper bound ...” The main area of uncertainty centered around the rapid changes observed on the ice sheets of Greenland and Antarctica just prior to the release of the IPCC’s 2007 report. Nicholls and team then reviewed a series of studies published after the IPCC AR4 release which looked at potential ranges of twenty-first century sea-level rise on the basis of more recent research. From this analysis they conclude that a “credible” maximum rise by 2100 would be about 2 meters (6.6 feet) but they stress that sea-levels rising to the upper part of this range are unlikely. Using the IPCC’s AR4 estimates they consider that a credible lower bound for the same time frame would be 0.5 meters (1.6 feet).
With 0.5 and 2 meters considered as the lower and upper bounding points, Nicholls and team then model a range of scenarios including amounts of land loss (from submergence and erosion), population numbers in vulnerable regions, regional socioeconomic capacities and varying levels of proactive coastal protection. Assuming a worst-case scenario of no adaptation they find that the total human population displaced over the twenty-first century would be a catastrophic 72 and 187 million people, respectively. If, however, coastal protection measures (dike construction, beach and shore nourishment) are successfully implemented then numbers of those displaced fall dramatically to 41,000 to 305,000. Adequate protection response is associated with considerable economic cost, however, which Nicholls and colleagues estimate as being at a minimum US $25 and $270 billion (1995 values) per year for 0.5 and 2 meters, respectively.
The study’s authors note that vulnerability to sea-level rise is not uniform and that the most geographically vulnerable regions – small islands, Africa and large parts of Asia – collectively contain the majority of potentially displaced peoples. These are the same regions with low adaptive capacity and, therefore, where adequate protection measures are most likely to not occur. They conclude that, “the threats to these vulnerable regions provide some of the strongest arguments for mitigation to avoid a 4ºC world. In addition, adaptive capacity needs to be enhanced in these vulnerable regions, regardless of the magnitude of sea-level rise.”
Source: Nicholls, R.J. et al. 2011. Sea-level rise and its possible impacts given a 'beyond 4 ºC world' in the twenty-first century. Philosophical Transactions of the Royal Society A 369(1934): 161-181.
Contact: Robert J. Nicholls, University of Southampton. E-mail: R.J.Nicholls@soton.ac.uk
A changing climate may further threaten food production and food security in the Pacific Islands. Stacy Jupiter/Marine Photobank
The Pacific Islands – a region comprised of 22 island states and territories in the south Pacific and a combined population of about 9.5 million – is particularly vulnerable to a changing climate argues Jon Barnett of Australia’s University of Melbourne in a recent paper published in Regional Environmental Change. His concern centers on overall food security, with a focus on impacts to fisheries and agriculture, the most important sources of local food production in the region, and on whether threats to food security could provide a basis by which to better define ‘dangerous’ climate change as delineated under the United Nations Framework Convention on Climate Change (UNFCC).
As would be expected in a region with a combined Exclusive Economic Zone (EEZ) covering 3,000,000 square kilometers (1,158,306 square miles) of ocean, fisheries are critical to both food supply and economic development. Fish consumption per capita is among the highest globally and constitutes an important source of protein. Artisanal fisheries provide livelihoods in many coastal communities and foreign-owned tuna fisheries operating in Pacific Island waters are responsible for an estimated 25,000 jobs and 50 per cent of all exports. Projected impacts on fisheries due to climate change include loss or alteration of fish habitat, shifts in species ranges or migratory routes, and increasing variability of supply. Agriculture, primarily conducted for subsistence in most of the Pacific Islands, is likely to be detrimentally affected by changes in the frequency and intensity of rainfall, heat stress, drought and saltwater contamination of groundwater by rising sea levels, among other potential impacts.
Barnett notes that climatic changes will be superimposed upon an existing array of environmental problems including, for example, soil loss, deforestation, depletion of freshwater resources, coastal erosion and coral reef degradation and loss. In addition, the region continues to experience declines in per capita food production and an increased reliance on food imports leading to a situation in which total food availability is, as Barrett explains, “increasingly becoming a function of the ability to pay for food imports.” He then argues that the added burden of a changing climate on food production and food resources accessed via fisheries and agriculture and on income generation and human health presents a real threat to food security.
The ultimate objective of the UNFCC is to ‘prevent dangerous anthropogenic interference with the climate system’ but, as Barnett points out, defining ‘dangerous’ in a way that all signatories to the convention can agree has proven to be exceedingly difficult. He proposes that a way around this is to assess ‘dangerous’ on the basis of food security. For the Pacific Islands, he concludes, it is indeed the case as climate change “puts at risk the very basic and universal need for people … to have access to sufficient, safe, and nutritious food at all times.”
Source: Barnett, J. 2011. Dangerous climate change in the Pacific Islands: food production
and food security. Regional Environmental Change 11(1): S229-S237.
Contact: Jon Barnett, University of Melbourne. E-mail: email@example.com
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