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Climate change is a global challenge that has no borders and to combat it requires coordinated work by all countries. In these pages, we tackle the subject from an objective, scientific viewpoint , discussing the causes and consequences of climate change and how it should be tackled. One of the MOST amazing video's and explinations on climate change.
As the global climate changes, rising sea levels, combined with high tides, storms and flooding, put coastal and island communities increasingly at risk. Protection can be achieved by building dikes or seawalls and by maintaining natural features like mangroves or coral reefs.
Communities can also adjust by reclaiming land from the sea and adapting buildings to cope with floods. However, all measures have their limits, and once these are reached people may ultimately have to retreat.
Choices made today influence how coastal ecosystems and communities can respond to sea level rise SLR in the future. Reducing greenhouse gas GHG emissions would not just reduce risks, but also open up more adaptation options. Sustainable development aspirations are at risk because many people, assets and vital resources are concentrated along low-lying coasts around the world.
Many coastal communities have started to consider the implications of SLR. Measures are being taken to address coastal hazards exacerbated by rising sea level, such as coastal flooding due to extreme events e. It is likely to rise 0. However, a rise of two or more metres cannot be ruled out. It could rise to more than 3 m by , depending on the level of GHG emissions and the response of the AIS, which are both highly uncertain. Even if efforts to mitigate emissions are very effective, ESL events that were rare over the last century will become common before , and even by in many locations.
Without ambitious adaptation, the combined impact of hazards like coastal storms and very high tides will drastically increase the frequency and severity of flooding on low-lying coasts. SLR, as well as the context for adaptation, will vary regionally and locally, thus action to reduce risks related to SLR takes different forms depending on the local circumstances.
Such protection produces benefits that exceed its costs in low-lying coastal areas that are densely populated, as is the case for many coastal cities and some small islands, but in general, poorer regions will not be able to afford hard protection.
Land can be reclaimed from the sea by building outwards and upwards. Avoiding new development commitments in areas exposed to coastal hazards and SLR also avoids additional risk.
For those unable to afford protection, accommodation or advance measures, or when such measures are no longer viable or effective, retreat becomes inevitable. Millions of people living on low-lying islands face this prospect, including inhabitants of Small Island Developing States SIDS , of some densely populated but less intensively developed deltas, of rural coastal villages and towns, and of Arctic communities who already face melting sea ice and unprecedented changes in weather.
The resultant impacts on distinctive cultures and ways of life could be devastating. Difficult trade-offs are therefore inevitable when making social choices about rising sea level. Institutionalising processes that lead to fair and just outcomes is challenging, but vitally important. Choices being made now about how to respond to SLR profoundly influence the trajectory of future exposure and vulnerability to SLR.
If concerted emissions mitigation is delayed, risks will progressively increase as SLR accelerates. Prospects for global climate-resilience and sustainable development therefore depend in large part on coastal nations, cities and communities taking urgent and sustained locally-appropriate action to mitigate GHG emissions and adapt to SLR.
This chapter assesses past and future contributions to global, regional and extreme sea level changes, associated risk to low-lying islands, coasts, cities, and settlements, and response options and pathways to resilience and sustainable development along the coast. Global mean sea level GMSL is rising virtually certain 1 and accelerating high confidence 2. The sum of glacier and ice sheet contributions is now the dominant source of GMSL rise very high confidence.
GMSL from tide gauges and altimetry observations increased from 1. The dominant cause of GMSL rise since is anthropogenic forcing high confidence. GMSL was considerably higher than today during past climate states that were warmer than pre-industrial, including the Last Interglacial LIG; — ka , when global mean surface temperature was 0.
Ongoing uncertainties in palaeo sea level reconstructions and modelling hamper conclusions regarding the total magnitudes and rates of past sea level rise SLR. In coastal deltas, for example, these drivers have altered freshwater and sediment availability high confidence. In low-lying coastal areas more broadly, human-induced changes can be rapid and modify coastlines over short periods of time, outpacing the effects of SLR high confidence. Adaptation can be undertaken in the short- to medium-term by targeting local drivers of exposure and vulnerability, notwithstanding uncertainty about local SLR impacts in coming decades and beyond high confidence.
Coastal ecosystems are already impacted by the combination of SLR, other climate-related ocean changes, and adverse effects from human activities on ocean and land high confidence. Attributing such impacts to SLR, however, remains challenging due to the influence of other climate-related and non-climatic drivers such as infrastructure development and human-induced habitat degradation high confidence.
Coastal ecosystems, including saltmarshes, mangroves, vegetated dunes and sandy beaches, can build vertically and expand laterally in response to SLR, though this capacity varies across sites high confidence. These ecosystems provide important services that include coastal protection and habitat for diverse biota. However, as a consequence of human actions that fragment wetland habitats and restrict landward migration, coastal ecosystems progressively lose their ability to adapt to climate-induced changes and provide ecosystem services, including acting as protective barriers high confidence.
Coastal risk is dynamic and increased by widely observed changes in coastal infrastructure, community livelihoods, agriculture and habitability high confidence. As with coastal ecosystems, attribution of observed changes and associated risk to SLR remains challenging. Drivers and processes inhibiting attribution include demographic, resource and land use changes and anthropogenic subsidence.
A diversity of adaptation responses to coastal impacts and risks have been implemented around the world, but mostly as a reaction to current coastal risk or experienced disasters high confidence.
Hard coastal protection measures dikes, embankments, sea walls and surge barriers are widespread, providing predictable levels of safety in northwest Europe, East Asia, and around many coastal cities and deltas. Ecosystem-based adaptation EbA is continuing to gain traction worldwide, providing multiple co-benefits, but there is still low agreement on its cost and long-term effectiveness.
Advance, which refers to the creation of new land by building into the sea e. Retreat is observed but largely restricted to small communities or carried out for the purpose of creating new wetland habitat. Future rise in GMSL caused by thermal expansion, melting of glaciers and ice sheets and land water storage changes, is strongly dependent on which Representative Concentration Pathway RCP emission scenario is followed.
SLR at the end of the century is projected to be faster under all scenarios, including those compatible with achieving the long-term temperature goal set out in the Paris Agreement. GMSL will rise between 0. Beyond , sea level will continue to rise for centuries due to continuing deep ocean heat uptake and mass loss of the GIS and AIS and will remain elevated for thousands of years high confidence.
Under RCP8. Estimates of SLR higher than the likely range are also provided here for decision makers with low risk tolerance. These high rates challenge the implementation of adaptation measures that involve a long lead time, but this has not yet been studied in detail. Evolution of the AIS beyond the end of the 21st century is characterized by deep uncertainty as ice sheet models lack realistic representations of some of the underlying physical processes.
The few model studies available addressing time scales of centuries to millennia indicate multi-metre 2. There is low confidence in threshold temperatures for ice sheet instabilities and the rates of GMSL rise they can produce. Sea level rise is not globally uniform and varies regionally.
Subsidence caused by human activities is currently the most important cause of relative sea level rise RSL change in many delta regions. While the comparative importance of climate-driven RSL rise will increase over time, these findings on anthropogenic subsidence imply that a consideration of local processes is critical for projections of sea level impacts at local scales high confidence.
Many low-lying cities and small islands at most latitudes will experience such events annually by Greenhouse gas GHG mitigation envisioned in low-emission scenarios e. Low-emission scenarios lead to slower rates of SLR and allow for a wider range of adaptation options.
For the first half of the 21st century differences in ESL events among the scenarios are small, facilitating adaptation planning. Non-climatic anthropogenic drivers will continue to increase the exposure and vulnerability of coastal communities to future SLR and ESL events in the absence of major adaptation efforts compared to today high confidence.
The expected impacts of SLR on coastal ecosystems over the course of the century include habitat contraction, loss of functionality and biodiversity, and lateral and inland migration.
Impacts will be exacerbated in cases of land reclamation and where anthropogenic barriers prevent inland migration of marshes and mangroves and limit the availability and relocation of sediment high confidence. Under favourable conditions, marshes and mangroves have been found to keep pace with fast rates of SLR e.
In the absence of adaptation, more intense and frequent ESL events, together with trends in coastal development will increase expected annual flood damages by orders of magnitude by high confidence. However, well designed coastal protection is very effective in reducing expected damages and cost efficient for urban and densely populated regions, but generally unaffordable for rural and poorer areas high confidence.
Effective protection requires investments on the order of tens to several hundreds of billions of USD yr -1 globally high confidence.
While investments are generally cost efficient for densely populated and urban areas high confidence , rural and poorer areas will be challenged to afford such investments with relative annual costs for some small island states amounting to several percent of GDP high confidence. Even with well-designed hard protection, the risk of possibly disastrous consequences in the event of failure of defences remains. Risk related to SLR including erosion, flooding and salinisation is expected to significantly increase by the end of this century along all low-lying coasts in the absence of major additional adaptation efforts very high confidence.
While only urban atoll islands and some Arctic communities are expected to experience moderate to high risk relative to today in a low emission pathway, almost high to very high risks are expected in all low-lying coastal settings at the upper end of the likely range for high emission pathways medium confidence.
While a slower rate of SLR enables greater opportunities for adapting, adaptation benefits are also expected to vary between coastal settings.
Although ambitious adaptation will not necessarily eradicate end-century SLR risk medium confidence , it will help to buy time in many locations and therefore help to lay a robust foundation for adaptation beyond All types of responses to SLR, including protection, accommodation, EbA, advance and retreat, have important and synergistic roles to play in an integrated and sequenced response to SLR high confidence. Hard protection and advance building into the sea are economically efficient in most urban contexts facing land scarcity high confidence , but can lead to increased exposure in the long term.
Where sufficient space is available, EbA can both reduce coastal risks and provide multiple other benefits medium confidence. Accommodation such as flood proofing buildings and EWS for ESL events are often both low-cost and highly cost-efficient in all contexts high confidence. Where coastal risks are already high, and population size and density are low, or in the aftermath of a coastal disaster, retreat may be especially effective, albeit socially, culturally and politically challenging.
Technical limits to hard protection are expected to be reached under high emission scenarios RCP8. Economic challenges to hard protection increase with higher sea levels and will make adaptation unaffordable before technical limits are reached high confidence.
For corals, limits may be reached during this century, due to ocean acidification and ocean warming, and for tidal wetlands due to pollution and infrastructure limiting their inland migration. Limits to accommodation are expected to occur well before limits to protection occur. Limits to retreat are uncertain, reflecting research gaps. Social barriers including governance challenges to adaptation are already encountered. Choosing and implementing responses to SLR presents society with profound governance challenges and difficult social choices, which are inherently political and value laden high confidence.
The large uncertainties about post SLR, and the substantial impact expected, challenge established planning and decision making practises and introduce the need for coordination within and between governance levels and policy domains.
SLR responses also raise equity concerns about marginalising those most vulnerable and could potentially spark or compound social conflict high confidence.
Despite the large uncertainties about post SLR, adaptation decisions can be made now, facilitated by using decision analysis methods specifically designed to address uncertainty high confidence. These methods favour flexible responses i. They use robustness criteria i. One example is adaptation pathway analysis, which has emerged as a low-cost tool to assess long-term coastal responses as sequences of adaptive decisions in the face of dynamic coastal risk characterised by deep uncertainty medium evidence, high agreement.
The range of SLR to be considered in decisions depends on the risk tolerance of stakeholders, with stakeholders whose risk tolerance is low also considering SLR higher than the likely range. Adaptation experience to date demonstrates that using a locally appropriate combination of decision analysis, land use planning, public participation and conflict resolution approaches can help to address the governance challenges faced in responding to SLR high confidence.
During exercise, the human body needs a greater amount of oxygen to meet the increased metabolic demands of the muscle tissues. Various short-term respiratory changes must occur in order for those metabolic demands to be reached. Eventually exercise can induce long term cardiovascular and respiratory changes, which can be both healthy and unhealthy. During exercise, carbon dioxide levels the metabolic waste rise in arterial blood. Carbon dioxide induces vasodilation in the arteries while the heart rate increases, which leads to better blood flow and tissue perfusion, and better oxygen delivery to the tissues. In particular, the blood flow to the brain and heart is increased, while increased blood flow to the muscles makes exercise easier. Additionally, the respiratory rate increases as a result of higher carbon dioxide levels through chemoreceptor regulation , which allows the body to release more carbon dioxide while increasing oxygen intake.
Sea-level rise is a major effect of climate change. It has drawn international attention, because higher sea levels in the future would cause serious impacts in various parts of the world. There are questions associated with sea-level rise which science needs to answer. To what extent did climate change contribute to sea-level rise in the past? How much will global mean sea level increase in the future?
In addition, the sea level experienced on Pacific islands can also be affected by vertical land movements that can either increase or decrease the effects of the rise.
Ocean acidification is a direct consequence of increased human-induced carbon dioxide CO 2 concentrations in the atmosphere. Ocean acidification is happening in parallel with other climate-related stressors, including ocean warming and deoxygenation. Interaction between these stressors is often cumulative or even multiplicative, resulting in combined effects that are more severe than the sum of their individual impacts.
Donald A. By the year it is expected to have grown to between nine and ten billion people. During this time of dramatic population growth, the human impact on the planet has increased significantly, not only because of the huge increase in our numbers, but also because of the new technical power to dig deeper, cut faster, build larger, and traverse more quickly great distances in automobiles, trucks, and planes.
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Adverse eﬀects of sea level rise in coastal areas are generally considered as a major threat of. climate change if we consider that 10% of the.