Using Projected Climate Change Impact on Coral Reefs to Explore a New Framework for Equity

by Wendy Noreña

The effect of greenhouse gas (GHG) emissions on ecosystem services is a subject of major concern in climate policy and conservation. Coral reefs are considered an especially vulnerable ecosystem as they are projected to be highly affected by ocean warming and acidification, both of which are generally thought to be likely consequences of climate change. While much research has already been conducted to determine the damage coral reefs will suffer as a result of climate change, surveys of how individual countries will be affected by coral reef devastation have not yet been implemented. Wolff et al. model both in this study, showcasing projected climate stress on reefs from 1875 to 2050 alongside measures of vulnerability and equity for individual countries and regions based on GHG emissions per capita and expected reef devastation. The study finds an alarming decoupling between total GHG emissions and reef impact, indicating that, in general, countries that emit the most GHG will often experience less reef impact while the opposite is true for countries that emit very little GHG.

Wolff et al. use a modified version of a vulnerability framework that determines a nations’ exposure, sensitivity, and adaptive capacity to the effects of climate change, adding in a measurement for, “equity.” This addition is meant to better assess the differences in climate change impact from country to country and is based on expected climate stress relative to the predicted climate stress for a nation. Coral reefs were ideal to implement this experimental equity framework as they can be found worldwide, are affiliated to countries with varying amounts of GHG emissions, have confirmed climate change effects that are relatively easy to model, and are at least loosely correlated with human health and the impact of climate change on human communities. Reefs were separated into 115 exclusive economic zones, or EEZs, though only 92 were used in the equity calculations. Climate stress was measured by modeling the effects of ocean acidification and warming on coral cover based on current projections for possible global temperature increases. Stress was then compared to the per capita CO2 emissions of all the sampled nations, resulting in an interesting comparison between how much climate stress a country would experience compared to how much it had actually contributed to global climate stress in the form GHG emissions.

Wolff et al. found that, overall, most of the “winners,” or countries with the highest emissions and lowest negative impact were in the northwest Atlantic, made up only 17% of the studied EEZs, and included such states as the US Virgin Islands, Netherland Antilles, United States, Trinidad, and Tobago. The losers, or those with the most devastation relative to their emissions, made up a startling 53% of those sampled and included Tanzania, Madagascar, Mozambique, and the Comoros, while EEZs with comparable emissions to impacts, like Jamaica, Panama, and China, made up only 17%.

Only seven countries had sufficient data in all the framework criteria to generate comparable vulnerability scores. Fortunately, these countries represented a variety of GHG emissions and climate stress levels. Using these data, it was possible to ascertain that there is indeed a correlation between vulnerability and equity, suggesting that if a country has a low vulnerability score (a good thing), it would likely have a high equity score and vice versa. This new equity framework provides a new way in which to view country inequalities along the gradient from most developed to the least developed and could be used by international funding groups like the Global Climate Fund to determine where to distribute funds and which countries should be donating. Indeed, Wolff et al. seem hopeful that their equity framework will be used to compare other ecological effects of climate change between countries and that one day it will be widely implemented in policy-making decisions as a way to more fairly execute equitable climate mandates. However, because of the uncertain nature of global ecosystems, climate change, and the simplistic country data used in this study, there may be inaccuracies in the equity framework that would benefit from more precise measurements. Regardless, this new equity-based method for considering climate change impact has serious promise to shape future policy, especially as global organizations move forward to address uneven climate change damages and their potential solutions.

Wolff, N. H., Donner, S. D., Cao, L., Iglesias-Prieto, R., Sale, P. F. and Mumby, P. J. (2015), Global inequities between polluters and the polluted: climate change impacts on coral reefs. Global Change Biology, 21: 3982–3994.


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