Do Paris Agreement Temperature Goals Address Sea Level Rise and Climate Justice?

December 20, 2022 | 8:36 am
Maldives Minister of Fisheries and Agriculture Dr Ibrahim Didi signs the decree of underwater cabinet meeting.Mohamed Seeneen/Flickr
Shaina Sadai
Hitz Fellow

Sea level rise presents numerous climate justice issues. Some of the venues where people are addressing the injustices of climate change are UN climate negotiations, the courts, and community organizing efforts around the world. Climate justice research can help inform these conversations.

New research that I led as part of my PhD dissertation, which was just published in Earth’s Future, digs deep into the topic of sea level rise and climate justice. In the study, we found that political power dynamics shape international negotiations, that the Paris Agreement temperature goal doesn’t fully account for the dangers of sea level rise, and that climate justice requires fully considering diverse views and experiences of climate change. Using new sea level rise modeling, we also showed that nations in the Alliance of Small Island States could experience as much as 34 percent more sea level rise from Antarctica than the global average.

One element of the Paris Agreement, the international effort to confront climate change, is a goal based on globally averaged air temperature rise, called the long-term temperature goal. The goal aims to limit global average temperature rise to 2 degrees Celsius above preindustrial levels, with effort made to limit it to 1.5 degrees C.

While conducting research for my PhD, I found that, as Antarctica starts to melt, it can actually slow down global average temperature rise. And it wasn’t only my research that showed this. Many other teams found the same result. But if Antarctica starts to collapse, it will raise sea levels, inundating coastlines around the world. Thinking about this problem—that the same ice sheet collapse raising sea levels could also slow temperature rise—I wondered how the research could interface with policy.

Our research began, as all research does, with a question: What does the interplay between sea level rise, Antarctica’s melting, and global average temperature rise mean for climate justice?

To answer that question, an interdisciplinary team of researchers reviewed hundreds of papers and calculated new sea level rise projections, blending methods from both physical and social science to gain a more holistic understanding.

What do the findings mean for climate justice?

We hear the phrase climate justice used a lot, but what does it mean and what does it mean in the context of this research?

Climate justice can mean different things to different people, especially for people experiencing harmful climate impacts.

In our research, we used what is sometimes called the three-fold approach, which is rooted in longstanding work by philosophers and has been adapted for climate and environmental issues. It is based on three interrelated aspects:

  • Procedural justice: Is the decision-making process for addressing harm equitable?
  • Distributive justice: How are a given situation’s benefits and harms distributed among people across space and time?
  • Recognition justice: Is the well-being of diverse groups respected?

Using this framework, my newly published research investigates climate justice in the context of sea level rise and the long-term temperature goal.

Procedural Justice: The Power and Influence Shaping Decisions

The Paris Agreement’s long-term temperature goal is how the UN Framework Convention on Climate Change (UNFCCC) negotiations settled on how to quantify the dangers of anthropogenic climate change. But limits on globally averaged temperature rise are only one option for how to measure danger, and they don’t account for spatial variation in climate impacts. Early proposals for how to assess danger included binding limits on heat-trapping emissions, different types of metrics based on temperatures and sea level rise, or combinations of these options.

Our research found that political power is central to how negotiations operate, and how the long-term temperature goal was developed and adopted. Historically high-emitting nations such as the United States have a lot of power in negotiations, in part because their approval is extremely important for whether a proposal moves forward. A case in point is the Kyoto Protocol, an early attempt within the UNFCCC to require industrialized nations to reduce greenhouse gas emissions by a certain amount in a given time period. The United States’ failure to ratify the Kyoto Protocol was just one aspect of the turning point that shifted negotiations away from proposals that required countries to reduce heat-trapping emissions. (For more details, check out this paper and the historical accounts it cites.)

Another actor with immense political power and influence played a role in this shift: the fossil fuel industry. Fossil fuel companies wanted to make sure that regulation of their products, and as a result the heat-trapping emissions that come from producing and using fossil fuels, were kept out of international agreements. To this day, fossil fuel lobbyists are still attending UNFCCC meetings to make sure the negotiations don’t interfere with their business plans.

When UNFCCC negotiations shifted away from focusing on reducing heat-trapping emissions and toward the goal of limiting temperature rise, the Alliance of Small Island States played a key role in shaping the conversations on temperature-based goals. With their tireless advocacy for the people who are most impacted by climate change, encapsulated by their slogan “1.5 to stay alive,” the alliance worked hard to ensure the 1.5 degree C target was included in the final text of the Paris Agreement. We know that climate damages get much worse between 1.5 and 2 degrees C, so this advocacy was crucial in securing a more just outcome from the negotiations once the use of a temperature target became inevitable.

Distributive Justice: Sea Level Rise is Irreversible and Spatially Variable

Sea level rise is detrimental for many reasons, and the science on how it works has evolved over time. One main issue is that sea level rise is essentially irreversible, meaning that once it goes up it isn’t dropping back down for thousands of years. And near-term policy decisions will be the deciding factor on how high seas rise and how fast that happens. Even under the most optimistic scenarios, such as limiting temperature rise to no more than 1.5 degrees C above preindustrial levels, sea levels will rise for hundreds to thousands of years. The higher the temperature rise, the more sea level rise is locked in.

This dynamic has huge implications for multigenerational justice because people living hundreds of years from now will have a highly altered landscape from emissions that warmed the planet long before they were born. When considering climate justice, it is very important for policy decisions to be made with future generations in mind.

Sea level rise is also different in different locations. The oceans don’t fill up like a bathtub with the water rising at the same level everywhere. Instead, sea level rise varies across space and changes over time. This is due to many different effects, for example changes in ocean heat and shifts in currents, or how melting ice sheets affect Earth’s gravity. In some places, such as at the coastlines of many Alliance of Small Island States members, sea levels are already rising quicker than the global average.  

The use of temperature as a metric for climate action changed many things about the way we approach policy decisions. While sea level rise is essentially irreversible, temperature rise—in theory—can be reversed to some extent. When the Intergovernmental Panel on Climate Change reports summarize different pathways in which warming is limited to 1.5 or 2 degrees C above preindustrial levels, there are two types of pathways considered: those in which the temperature never surpasses those values, and those in which the temperature surpasses those values and then is brought back down through speculative technologies that capture emissions. The second type of pathways, called “overshoot pathways,” are a feature of temperature targets. If limiting sea level rise had been used as a goal, however, there would be no such a thing as an overshoot pathway because sea level rise cannot be reversed like temperatures theoretically can.

Overshoot pathways are also based on modeling that minimizes costs of implementing those pathways, but this modeling doesn’t include the cost of the climate damages that would occur during the time that temperature overshoots the stated temperature limits. These factors present a climate justice challenge. This isn’t to say that they should not be used, but that caution is needed. It is much less dangerous to reduce heat-trapping emissions now and never surpass 1.5 degrees C than it is to surpass it and hope that the technology works as promised and the temperature can be brought back down.

Recognition Justice: The Disparate Impacts of Sea Level Rise

Sea level rise will continue for the foreseeable future and have greater impact in some places than in others. As the ocean rises, coastal and island communities will suffer from increased flooding and the loss of homes, cultural sites, and potentially, lives. The ways a particular place experiences climate damage is shaped by its history. Colonization perpetrated by high-emitting nations reduced the ability of many communities and peoples to adapt to environmental damages. Colonial legacies play into the landscape of political power in negotiating rooms as well as in such things as adaptation funding and debt. Acknowledgement of this is a key facet of climate justice, since harm cannot be addressed without being acknowledged.

The Alliance of Small Island States often mentions that sea level rise can potentially lead to some islands becoming uninhabitable and may even fully submerge them. This presents a number of justice issues and legal questions. The initiatives currently being led by Vanuatu and the Commission of Small Island States on Climate Change and Law to seek Advisory Opinions at the International Court of Justice and the International Tribunal for the Law of the Sea will help clarify how international law relates to climate change. These efforts are crucial for addressing many of the justice issues our new research paper discusses. The groundwork that was laid at recent UN Conference of the Parties (COP27) in Egypt to establish a fund to pay for climate change loss and damage, which the Alliance of Small Island States played a key role in, is another avenue for addressing questions of climate justice and the damages caused by sea level rise and other climate impacts.

The role of the Antarctic Ice Sheet

The climate justice issues of sea level rise mentioned above would still exist regardless of what ultimately happens with the Antarctic Ice Sheet, but large-scale Antarctic collapse would exacerbate all of them. Antarctica is thought to be unstable in many locations and, as temperatures rise, it may ultimately become the largest contributor to rising seas.

Gravity, the Earth’s rotation, and the way the Earth’s bedrock changes as ice sheets change all contribute to how sea level rise varies spatially around the world. As Antarctica collapses, these factors mean that the resulting sea level rise is generally highest in the center of the Pacific and Indian Oceans and in the Caribbean. Our new research shows that Alliance of Small Island States locations are projected to experience sea level rise from Antarctica at 34 percent higher than the global average. This is particularly unjust given that they have contributed virtually nothing to heat-trapping emissions.

This graphic shows how changes to sea level from Antarctic melt would vary around the world. The purple line indicates locations that would experience the global average value of the Antarctic contribution to sea level rise while the areas in dark blue are places that would experience a larger effect. The numbers in the legend correspond to how many times higher than the global average sea level rise would be in a given location, for example in places with a value of 1.2 they would experience 1.2 times the global mean. Alliance of Small Island States member nations are all labeled on the map. Image via Sadai et al., 2022.

As Antarctica begins to collapse, it can slow down the rise of temperature, this is called a climate feedback. This occurs because the melting ice causes changes to the way heat is transported and stored. This feedback could potentially mean there would be a longer amount of time before a given temperature target could be reached. However, feedbacks are not generally included in determining how much more heat-trapping emissions would be allowed under a given temperature target, so it is unclear how climate feedbacks would affect carbon budgets.

Since large scale melting of Antarctica is likely to happen after 2100, the way it would slow temperature rise could have important implications if temperature-based goals are used after 2100. This would be further complicated by any other climate feedbacks that come into play. By raising this climate justice concern, we hope that these issues can be taken seriously in negotiations, which should take into account intergenerational climate justice.

Raising a critical issue

Our new research paper is not trying to present an alternative to the Paris Agreement’s long-term temperature goal. Rather, we use a unique interdisciplinary lens to understand what the goal means for climate justice when considering sea level rise.

Our research shows that sea level rise will lead to many injustices, which are unevenly distributed across space and time and reach far into the future, and that political power dynamics shape how negotiations play out. The Alliance of Small Island States continues to play a crucial role in UN climate negotiations, as they have done for decades, and they stress the impacts of sea level rise in their work. The unstable nature of the Antarctic Ice Sheet also complicates the issues of sea level rise and presents new climate justice concerns.

Understanding these issues can help advocates push for a more just future.

Note: The full research paper this blog summarizes is open access and available here.