Majuro, the capital of the Marshall Islands, where residents have had to build homemade seawalls to protect their homes and communities. Photo Credit: Kadir van Lohuizen / NOOR
The 2021 Intergovernmental Panel on Climate Change (IPCC) report on climate change is a “code red” for humanity. On the track we are headed, the global surface temperature of the earth will exceed 1.5 to 2 degrees Celsius during the 21st century. Changing this trajectory will require a major and unprecedented collective reduction of carbon emissions. This seems unlikely since every multilateral climate commitment or resolution ever has failed or seriously underperformed. Already, global warming is directly tied to sea level rise and is contributing to the loss of land, increasing severity of storms, loss of sea life, and has major implications for human health and livelihoods. Given that sea level rise has already reached numerous tipping points, global leaders and communities must work to adapt to the new reality of the Rising Dilemma of the century.
The Rising Dilemma: Sea Level Rise is the Most Dangerous, Irreversible Threat to Humanity
Ninety-one percent of the warming experienced due to climate change is being absorbed by the ocean. Under intermediate, high, and very high emission scenarios of the 2021 IPCC report, global temperatures will increase by 1.5 degrees Celsius or 2.7 degrees Celsius by the end of the 21st century. This has major and irreversible consequences for our planet: since water expands as it warms, these warming global temperatures contribute to ocean temperature warming and thermal expansion. Between 1971 and 2018, thermal expansion was the primary cause of sea level rise, accounting for fifty percent of the global rise in sea level. Additionally, global warming contributes to glacial retreat, ice sheet melt, and land-water storage issues. Glacial retreat and ice sheet melt contributed to twenty-two and twenty percent of sea level rise, respectively, between 1971 and 2018.
The implications of thermal expansion along with glacial melt and ice sheets are vast and are displayed in Table 1 below.
Table 1: Implications of Thermal Expansion and the Melting of Glaciers and Ice Sheets on Sea Level and Ocean Life
| Issue: | Why is this happening? | Implications: |
| Thermal Expansion | Rapidly warming atmospheric temperatures are being absorbed by the ocean water, which expands as it warms. | Sea level rise, loss of sea life and coral reefs due to rapid temperature changes |
| Glacier Melting | Rapidly warming atmospheric temperatures are causing glaciers to melt. | Sea level rise, the reduction of salinity and increase in acidity in the ocean, and loss of sea life since glaciers are made up of freshwater. |
| Ice Sheet Melting | Rapidly warming atmospheric temperatures are causing ice sheets to melt. | Sea level rise and changes ocean chemistry since ice sheets are made up of saltwater with added nutrients which can lead to loss of sea life. |
As Table 1 demonstrates, accelerated global warming and the continued rise in temperature are causing irreversible changes to the ocean. Unfortunately, we cannot reduce sea level rise once it has happened, and we cannot re-alter the chemistry of the ocean. For these reasons, rising sea levels are one of the most concerning slow-onset climate events. The unique and severe progression of sea level rise is concerning and has major implications for all life on earth. No life on earth will be untouched by the implications of sea level rise, especially now that its progression has already surpassed major tipping points.
Tipping points of the Global Warming and Sea-Level Rise Nexus
In 2020, a global warming benchmark was reached when the combined global land-ocean temperature warming was 1.02 degrees Celsius. This is a global warming tipping point that will lead to irreversible changes regardless of future mitigation. Nevertheless, scientists insist that it will be catastrophic if global temperature warming increases by the predicted 1.5 degrees Celsius or 2 degrees Celsius by the end of the century. Already, there are major indicators that we have already surpassed tipping points in ice sheet melt and glacial retreat which will contribute to an unprecedented rise in sea levels.
For example, such benchmarks have already been reached in Greenland and the Arctic. The Greenland ice sheet melting rates in the Jakobshavn basin are extremely concerning: the ice sheet lost four trillion tons of ice between 1992 and 2018. The ice sheet is vulnerable to melt with global warming between 0.8 degrees Celsius (which we have surpassed) and 3.2 degrees Celsius. If the entire ice sheet melts, this could cause sea levels to rise globally by an additional twenty feet. This level of warming would also contribute to the collapse of the West Antarctic Ice Sheet (WAIS), which has already lost one trillion tons of ice in the last twenty years.
Though 140 countries have committed to the net-zero targets outlined in the Paris Agreement, the climate is still estimated to reach the 1.8 degrees Celsius benchmark by 2100. Worse, if carbon levels continue to increase, the global mean sea level will rise by two meters (nearly seven feet), roughly the length of a buffalo, by 2100 and five meters (over sixteen feet), taller than an adult African elephant, by 2150. While this is the worst-case scenario, it is still a possible scenario. If this happens, humans must be prepared for the massive upheaval, displacements, and impact on communities that these shifts will cause.
A Survey of Global Impact of Sea Level Rise
Since we have already surpassed the tipping points discussed in the previous section, we should expect the following catastrophic implications of sea level rise. In some regions, sea level rise is already impacting livelihoods through loss of land, increasing severity of storms, loss of sea life, and impacts on human health.
Loss of Land
The sea level rises one-eighth of an inch per year. As mentioned, at our current pace, experts estimate that there will be a twenty percent increase in mean sea level rise across more than two-thirds of the global coastline by the end of the century. This rising sea level will lead to coastal erosion and in some cases will lead to some islands being completely swallowed by the ocean. Small Island Developing States (SIDS) and low-lying countries, which have contributed the least to global emissions, are the most immediately impacted by sea level rise. For example, it is estimated that in Bangladesh, a low-lying, populous country in South Asia, one in every seven people will be displaced by 2050 due to sea level rise, saltwater intrusion, and severe storms. Numerous SIDS across the South Pacific and Caribbean, including Tuvalu, Kiribati, Haiti, Jamaica, and the Marshall Islands, may be uninhabitable in the future for similar reasons. It is especially important to closely monitor SIDS since twenty-six percent of SIDS are less than five meters above sea level, making them extremely vulnerable.
Sea level rise and its effects already contribute to protracted migration and temporary relocations during storms, and it will pose an existential threat to many islanders. Coastal cities and communities around the globe are also threatened by sea level rise and the subsequent coastal erosion and increased flooding. Cities including New York City, Miami, Boston, Hong Kong, Mumbai, Lagos, Shanghai, Dhaka, and Tokyo will each be impacted by the rapid sea level rise. The damage and loss of infrastructure in urban centers and the subsequent economic consequences of sea level rise will seriously alter life across the globe. Global leaders must prepare.
Increasing Severity of Storms
In addition to increasing flood risk and coastal erosion, sea level rise influences the severity and impacts of El Niño and La Niña weather events. The Caribbean is especially vulnerable to the severe impact of storm surges and increasingly severe hurricanes and cyclones. For example, Hurricane Maria devastated Puerto Rico in 2017 and the island is still recovering. The impacts of the hurricane include thousands of lost lives, major blackouts across the island, inadequate provision of basic services including healthcare, and food and water shortages. In addition, Puerto Rico sustained more than $90 billion in damage, an 80 percent loss in crop value, and a reduction in tourism upon which the economy is dependent. This is only one example of the economic loss and damage experienced by the increasing severity of storms. SIDS and low-lying countries with limited resource capacity need major economic support and programming to mitigate the losses associated with storm surges.
Loss of Sea Life and Impacts on Human Health
Sea level rise threatens coral reefs and sea life. Sea level changes the acidity of the ocean and impacts fishery production. This has happened across Bangladesh as well as in the Maldives and Jamaica and across other SIDS. The loss of sea life could lead to food scarcity issues in some regions and has already impacted aquaculture economies across SIDS and Bangladesh. Additionally, sea level rise increases the probability of saltwater intrusion in groundwater aquifers. The rising sea levels also contribute to reducing the amount of potable water available in already water-scarce regions: saltwater intrusion increases treatment costs for groundwater resources and can make aquifers unusable altogether. This is especially concerning given the already present issues surrounding groundwater depletion and water scarcity.
Adaptation and Mitigation Mechanisms: Global and Regional
International Action: Mitigation
The 1996 Kyoto Protocol outlines the commitments of high-income countries to limit greenhouse gasses (GHG) emissions through policy and mitigation measures. The carbon reduction targets were not met when the first commitment period ended in 2012 and did not result in a reduction of five percent against 1990 levels, as countries had pledged. The Doha Amendment established the second Kyoto commitment period between 2013 and 2020. The amendment, which codified commitments to reduce emissions to eighteen percent below the 1990 emissions range, also failed. As mentioned previously, the Paris Agreement has been adopted by all United Nations Framework Convention on Climate Change (UNFCCC) members in the hope that these pledges will curb emissions and mitigate the impacts of global warming. However, even with perfect adherence to net-zero goals, global warming will continue and will cause irreversible changes to the environment, including sea level rise. While the Conference of the Parties (COP) meetings continue to discuss the mitigation of climate change effects, like sea level rise, there remain inadequate monitoring mechanisms or penalties for countries that fail to adhere to the pledge. In short, international action on climate change mitigation is failing, and this has major implications for the future impact that rising sea levels will have on communities across the globe.
Regional and National Action: Adaptation
While the international community grapples with the best ways to reduce emissions and mitigate the impacts of climate change, communities across the globe that are impacted by sea level rise are instituting regional and national mechanisms to adapt to climate change. Some countries, like Australia, are thinking in the short term about constructing seawalls and levee structures to combat climate change. Others are focusing on natural restoration and ecological development. Nevertheless, one major adaptation mechanism for many communities is migration, both temporary and protracted. Some countries, including Bangladesh and Japan, are instituting planned relocations to reduce the loss of life and damage associated with severe storms resulting from sea level rise. Others are utilizing visa waivers and economic integration schemes to deal with the loss of land across low-lying islands, storm intensification, and economic losses associated with sea level rise. Two examples of this are Caribbean Community (CARICOM) and the Organization of Eastern Caribbean States (OECS), which each have mechanisms for temporary and long-term absorption of climate-affected populations, especially following severe storms and sudden-onset events that are worsened by sea level rise.
Due to the vulnerability of SIDS, the Alliance of Small Island States (AOSIS) was created to call upon the United Nations for increased investment in resilience, adaptation, and mitigation mechanisms. This action led to the development of the Small Island Developing States Accelerated Modalities of Action (SAMOA Pathway) to institute adaptation on a regional level, which establishes resilience and funds sustainable economic development programming. These adaptation and resilience mechanisms should be bolstered, especially by countries that have contributed most to carbon emissions.
Concluding Remarks
Currently, collective efforts to curb emissions and mitigate the impacts of sea level rise are abysmal. The international efforts should begin with progressive commitments from high-income countries that contribute most to global emissions. It is essential that countries publicly monitor and report progress on the implementation of commitments. There should be economic and diplomatic consequences if countries fail to uphold and implement their commitments. Countries that contribute least to carbon emissions yet are most vulnerable to the implications of sea level rise, like SIDS, must receive unique development support and access to climate migration pathways to ensure safety. In some cases, migration will be the only adaptation strategy for islands that will sink into the ocean. In these cases, high-income and high-carbon contributing countries must step up to absorb these populations. In the meantime, these high-income countries should work collectively to bolster sustainable development programming and support the provision of essential services in vulnerable regions.
Through an analysis of sea level rise, its severe progression, and already reached benchmarks, this article outlines the scope of the Rising Dilemma. It then presents a survey of known impacts of sea level rise, with case study examples, to illustrate the severe effects that sea level rise has on communities. Finally, it discusses the limited actions taken by the international community to mitigate climate change and the unique adaptation and mitigation strategies countries, and individuals, are employing. How we respond, and whether we respond, to the Rising Dilemma will be the question of the century.