Coral reefs are critical for our food supply , tourism , and ocean health . We can protect them from climate change

• Coral reefs provide ecosystem services worth $11 trillion dollars annually by protecting coasts, sustaining fisheries, generating tourism, and creating jobs across the tropics. • Ocean warming is the most widespread and immediate threat to coral reefs globally, followed by disease, and local stressors. • Management efforts help address local stressors, however, the root cause of global coral decline increasing temperatures caused by greenhouse gas emissions must be addressed to ensure the survival of the ocean’s most diverse habitats through the 21st century. • International climate agreements that aim to continually reduce emissions are our best hope for the survival of reefs.

This biodiversity is crucial for the health our oceans, and it can also be harnessed for natural product and drug development. For instance, the antiviral drug Vira-A, which is used to treat herpes simplex infections, as well as AZT, which is used to treat HIV, were derived from a compound (Ara-A) isolated from a Caribbean sponge that lives on coral reefs [14]. Another compound (Ara-C) was isolated from the same sponge and developed into the anti-cancer medication Cytarabine [14]. The drug Ziconotide for the treatment of chronic pain was isolated from cone snails found on coral reefs [15]. In addition, several new antibiotic compounds effective against antibiotic-resistance bacteria have been isolated from soft corals that live in coral reefs [16]. The skeletons of hard corals can even be used as bone regeneration materials for humans [17] Overall, the oceans represent a highly unexplored source of products for human medicine. The drug discovery potential in marine environments, and coral reefs in particular, should be considered an invaluable resource [18,19].

Fisheries and Tourism:
The biodiversity of corals reefs also includes fish and seafood species that form part of a 143 billion dollar global fisheries trade industry, such as groupers, lobsters, and snappers [20]. In the U.S., recreational fisheries on coral reefs are worth over $100 million each year. In addition, nearly half of all U.S. fisheries depend on healthy coral reefs ecosystems for sustainable stocks [21]. Excessive fishing on reefs can cause considerable damage and threaten the stability of the ecosystem (see fishing pressure section below). As such, coral reef fisheries benefit from strong management plans that limit the risk of overfishing important species.
Coral reefs also form the foundation of many tourism industries in coastal areas across the globe. In Australia, the Great Barrier Reef received over 26 million visitors in 2016, and tourism to the Queensaland area generates around $6.4 billion (AUD) annually [22]. In the U.S., reef-based tourism in the states of Hawai'i and Florida alone are estimated at over $2 billion dollars annually [23]; and at nearly $240 million in Puerto Rico [21]. 1

What's killing all the corals: Global and local threats to reefs
Despite their vast ecological, economical, and pharmaceutical importance, coral reefs are one of the planet's most rapidly degrading ecosystems [6]. On a global scale, corals are most severely impacted by increasing temperatures, coral diseases, and declining pH levels. At regional and local scales, stressors such as overfishing, run-off from land, and coastal development lead to coral mortality and reef degradation [24]. We discuss the causes, effects, and prevalence of different stressors below. While we have organized this section into global and local stressors, reefs are complex ecosystems and are often subjected to multiple stressors simultaneously. It should also be noted that this is not a comprehensive list. For instance, we do not discuss light and noise pollution, ship groundings, invasive species, or tourism pressure. We have focused on the stressors that we consider the most pressing to address given the magnitude of their impact.

Global Stressors
Temperature: Corals can suffer severe stress if water temperatures rise by just 1 • C above their usual summer maximum [25]. While this change in temperature may seem trivial at first, consider the impacts of a fever on human health, where only a 1-2 • C increase can quickly become life threatening. At higher temperatures, corals lose the 1 Values adjusted for 2020 dollars from the 2007 values reported in [21] Figure 2: Coral reef ecosystem services (blue) and threats (red). Reefs offer valuable services to humans. Unfortunately, corals are impacted by multiple threats, many of which act to compound each other. Image was created on biorender.com. Icon credits to Lluisa Iborra (skyline), Ifki Rianto (small fishing boat and fisherman), Ruliani (wave), Nikita Kozin (diver), and Luis Prado (large fishing boats), all available from The Noun Project. Reef and associated fish are original artwork by author H.E.R. symbiotic algae that live inside their tissues, and which provide the coral with the majority of their daily food requirements [25,26] (Figure 3A). This process is called 'bleaching,' as the symbionts are also the main source of color in coral tissue ( Figure 3B). Bleaching is often fatal to the coral animal, as they can starve to death without their symbionts. If temperatures return to normal within a few days or weeks, the coral can re-establish their community of symbionts and may survive; but this time window is becoming more elusive as heat stress events are becoming both more prolonged and more severe [27].
Since the 1980s, episodes of bleaching have reached reefs around the world, and even iconic and well-protected areas, like the Great Barrier Reef have lost up to 50% of their live coral [6]. Such bleaching events have increased in both frequency and intensity over the last two decades, and it is projected that by 2050 almost all reefs will experience bleaching level temperatures on an annual basis [27,28]. The most recent global bleaching event (between 2014-2016) caused devastation across the globe [3]. For instance, this event caused 100% bleaching and nearly 95% coral mortality on Jarvis Island, a U.S. territory in the central Pacific [29]. This island had previously been rated as the healthiest and most robust coral ecosystem on the planet [30], and lacks any other sources of coral stress, underscoring the pervasive impact climate change can have on even the most remote and pristine ecosystems. The Great Barrier Reef in particular, has continued to experience bleaching events every year since 2014, and is seeing its most widespread bleaching event this year [31]. On a smaller scale, other stressors can also prompt a bleaching response in corals, including cold temperature, pollution, high UV, and pathogens [16]. However, heat-induced mass bleaching remains the primary cause of coral decline on a global scale [4,28,32,33]. These declines emphasize the desperate need to curtail the carbon emissions that are responsible for increasing ocean temperatures.
Disease: Corals have also been affected by disease outbreaks, especially in the Atlantic/Caribbean, where they have been one of the main sources of decline from the mid 1970's to today [34]. In the late 1970's, an outbreak of white band disease decimated the three major Caribbean coral species (Acropora cervicornis, palmata, and prolifera) that were the dominant reef builders in the region [35]. In 2014, a new disease, now called Stony Coral Tissue Loss Disease (SCTLD), began in Miami-Dade County, and has since spread throughout the Caribbean [36]. The disease impacts more species than any other known coral diseases, and also kills corals more quickly [36]. In Florida alone, more than 30% of corals have died from the disease over the last few years [36]. Despite much investigation, scientists have yet to isolate the pathogen that causes the disease.
Disease prevalence in corals has also been increasing over time and is sometimes exacerbated by increased temperatures [37]. Combined, disease and bleaching are major causes of coral mortality, and both are predicted to worsen as climate change progresses [33,37]. Diseases can also be triggered by local stressors such as coastal human inputs. For instance, in Guam, prevalence of white syndrome was linked to increased nitrogen from sewage outfalls [38]. In Florida, the outbreak of SCTLD also coincided with the dredging of Port Miami, which led to substantial sedimentation and coral mortality [39] [40]. An overall increase in nutrients has also been linked to higher disease prevalence in the both field and experimental studies [41]. Given these synergies, outbreaks of coral diseases are expected to increase [42]. Management efforts that aim to limit sources of coral disease should be high priority especially in the Atlantic/Caribbean, where they have already caused substantial decline.
Ocean acidification (declining ocean pH): In addition to warming our planet, carbon dioxide emitted into the atmosphere dissolves into our oceans, triggering chemical reactions that increase the acidity of the water (lower the pH level) [43]. Some studies indicate that pH levels in reef water are declining more rapidly than in the open ocean [44]. At lower pH, the process that corals use to build their skeletons (calcification) and which creates the reef structure requires more energy, meaning coral growth slows and they build less reef [45]. The chemical dissolution of older reef structures, as well as erosion of live corals by live organisms, like encrusting mussels or worms, is also easier at lower pH [46,47].
Ocean acidification also negatively impacts the many shell-building organisms that reside on reefs, such as mussels, clams, urchins, and other calcifying organisms [48]. Even fish growth and metabolism can be impacted under low pH, especially during larval stages [49] In addition, pH often interacts negatively with warmer temperatures, hindering growth and survival of corals [50]. As with mitigating the effects of warming, addressing the root cause -rising CO2 levels -is the best course of action to prevent further damage.

Local Stressors
Coastal Development and Nutrient Enrichment: Coastal development can generate sedimentation from poor-land use practices and new development, or nutrient run-off from agriculture and wastewater discharge. The construction of new resorts may involve overwater bungalows, built directly on reef structures, or the creation of artificial beaches that change coastline dynamics and increase sedimentation to nearby reefs. The expansion of ports to accommodate cruise liners or large container ships, often requires dredging of the surrounding reef flats in smaller tropical islands [51,52], or even larger cities like Miami [40]. On a more dramatic scale, territorial conflicts in Spratly Islands in the South China Sea, have led to land reclamation techniques by China in which reefs are filled to create land that can be claimed [53]. Such efforts destroyed an estimated 6 square miles (3,000 football fields) of coral reef habitat in 2015 [54]. Coastal development represents a severe a direct physical risk to coral reef survival. The environmental impacts of development projects should be thoroughly assessed by independent parties prior to permitting to help alleviate such pressures.
Nutrient influx to reefs is primarily driven by human activity. Coastal development, sewage and water treatment effluents, agricultural runoff, and discharges from shipping can all increase nutrient levels on reefs. Macroalgae (different from the microalgae that live inside coral tissues) compete with corals for space on reef environments [55]. Normally, macroalgal growth is limited by nutrient availability, but with an influx of nutrients algae can grow more quickly and begin to grow over the coral [55]. This often results in a shift from a coral-dominated reef to an algal-dominated ecosystem [56] ( Figure 3B). These patterns can also be exacerbated if there is overfishing of herbivorous fish, which help keep macroalgal populations in check (see Fishing Pressure).
Algal-dominated habitats quickly begin to lose fish species that relied on corals for shelter [56]. Algae can also trap sediments, leading to negative feedback loops that further stress the remaining corals [57]. Algal-dominated reefs lose their value as protective barriers to shorelines, as dead corals can no longer create additional reef structure. In addition, nitrogen and carbon inputs from land can alter the pH of coastal waters, exacerbating ocean acidification in those areas [58]. Policies that limit the environmental impact of coastal development projects and ensure that coastal infrastructure (e.g. sewage pipes and water treatment plants) is well-maintained can significantly limit continued damage to coral reefs locally.
Fishing Pressure: Corals rely on healthy populations of herbivorous fish and invertebrates to keep macroalgal populations from outcompeting them [59]. Overfishing of herbivores like parrotfish and rabbitfish can result in algal population spikes [60,61]. In 1990, Bermuda banned pot fishing, a practice that mainly impacted herbivorous fish species. As a result, populations of herbivores rebounded [62]. Other fishing practices like dynamite (also called blast fishing) or cyanide fishing can directly destroy reef habitats and kill coral reef organisms. While these methods are not practiced in the U.S., they still represent a significant threat to reefs in the Indo-Pacific, where many U.S. and international non-profits dedicate efforts to reef conservation. Dynamite and cyanide fishing are often practiced by smaller-scale fishermen, harvesting coral reef fish for the aquarium trade (most of which is sent to U.S.) or direct consumption. In Tanzania, for example, dynamite fishing was outlawed in the 1970s, but has continued essentially unchecked [63]. Cyanide fishing allows for the live capture of fish by temporarily anesthetizing them [64]. The concentrations of cyanide used to target the desired fish, however, can be quickly detrimental to coral reef organisms, such as smaller fish and invertebrates [64]. Efficient enforcement against both these practices in the Indo-Pacific would be a substantial relief to local coral reefs; as would limiting overfishing of herbivorous species across coral habitats.

What's protected: U.S. policies addressing coral reefs
Reducing human access to reefs can mitigate the impact of local stressors on corals -buying them time to become more tolerant of global stressors [65]. Marine Protected Areas (MPAs) are defined as: "[an] area of the marine environment that has been reserved by federal, state, territorial, tribal, or local laws or regulations to provide lasting protection for part or all of the natural and cultural resources therein"   . The CRCP is one of few federal programs whose direct mission is to address coral reef conservation efforts and the only one with a legislative mandate. In addition to supporting the USCRTF, the CRCP's multifaceted work involves funding coral research, delivering sound scientific information and tools for management, establishing core partnerships with various stakeholders, and capacity building to help local staff members implement projects that address threats and restore habitats, among other functions. The monumental work of this program relies on federal funds appropriated by Congress. In addition, the U.S. Fish and Wildlife Service manages 10 coral reef National Wildlife Refuges in the Pacific and enforces international trade laws, which regulate the import and export of corals for jewelry or the aquarium trade. The Environmental Protection Agency protects coral reefs by implementing Clean Water Act programs that maintain water quality in watersheds and coastal zones of coral reef areas. While these functions are important, their pertinence to coral reefs is not congressionally mandated.
A summary of other key domestic policies and the primary agencies responsible for them is shown in Table 1. There are also several international policies that impact coral reefs, though the U.S. is notably absent from several (see gaps section below). The U.S. is contracting party of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES, 1973), which serves to regulate international trade of animal and plant samples in order to promote conservation and reduce the risk of overexploitation and extinction. All hard coral species (Scleractinia spp.) are listed in the CITES Appendix II, and transport of live specimens or products of these species requires a CITES permit (Resolution Conf. 9.24 Rev. CoP17, 1994).

What's missing: Management and policy gaps in coral reef conservation
The U.S. stance on ocean policy has varied across administrations. Mostly recently it has shifted from an emphasis on conservation and climate to a focus on economic and security concerns (Executive Order No. 13840, 2018). While the stringency of coral reef conservation has fluctuated, it remains indisputable, as described above, that coral reefs provide substantial economic benefits to many U.S. sectors, in addition to their contributions to biological diversity and ecosystem health. Executive Order 13840, Regarding the Ocean Policy to Advance the Economic, Security, and Environmental Interests of the United States, calls to "facilitate the economic growth of coastal communities and promote ocean industries", among other priorities (Executive Order 13840, 2018). It is clear from the lengthy list of ecosystem services that preservation of coral reefs is necessary for economic growth and security of many coastal communities.
While there are legal mechanisms (e.g., MPAs) to protect coral reefs under U.S. jurisdiction, gaps often remain in implementation and enforcement. For instance, many MPAs are in remote places where enforcement is difficult, even for countries with substantial resources [66,67]. When properly enforced, protection can help alleviate some, though not all, stressors. An evaluation of the ecological performance of MPAs in the U.S. Virgin Islands revealed that coral reefs outside MPAs showed larger declines in ecosystem performance, such as lower density of fish including adult snappers [68]. Notably, the amount of live coral cover decreased both inside and outside MPAs during the study period due to bleaching events and hurricane damage, pointing to the importance of global stressors in driving community structure [68]. has not yet proceed past the introduction stage. This legislation would a provide a strong base for coordinated national efforts as well as provides $160 million of federal funding for the next five years for domestic reef management, conservation, and restoration. Such increases in funding are desperately needed. For instance, the budget for CRCP has held steady around $27 million per year over the past ten years [69]. This stagnant budget supports work that is becoming increasingly demanding and urgent. Given the vast monetary value that coral reefs represent to the U.S., increasing this and other program budgets would expand their capacity and impact.
On a global geopolitical level, the U.S. has the potential to influence coral reef management in other regions, as well. The USCRTF has active working groups that address specific issues and produce incredibly detailed global, regional, and local recommendations based on science that need to be considered in national policy. For example, 60% of the aquarium fish trade is imported into the U.S., with almost 90% originating from Pacific regions [70,71]. While the U.S.AID's program in the Philippines and Indonesia are working to improve problems around both overfishing and destructive fishing (e.g. cyanide or dynamite fishing), the program's limited geographic scope and jurisdiction makes it difficult to coordinate and enforce the larger-scale regional efforts that are needed. To address this, the USCRTF has recommended leveraging work with the Asian Pacific Economic Cooperation (APEC) forum and building a strategic partnership with the South Pacific Region Environmental Program [72].
More broadly, however, the U.S. is not party to some major international conventions that would benefit coral reef ecosystems: • The United Nations Convention on the Law of the Sea (1982) defines the rights and responsibilities of countries with respect to ocean use in order to maintain peaceful relations between governments (U.N. Convention on the Law of the Sea, 1982). Currently, the U.S. has signed but not ratified the agreement, a move that may jeopardize future claims to ocean resources [73]. Within the agreement, the extent of coral reefs is used to help define the limits of territorial seas, and thus the continued loss of reefs has strong implications for future designations of maritime boundaries. reefresilience.org).
Coral restoration aims to increase the number of healthy adult corals on reefs. However, as corals may reproduce asexually (usually via fragmentation) or sexually, restoration also involves promoting asexual and sexual reproductive processes on reefs to increase coral abundance ( Figure 3C) [77,78]. In the U.S., the largest restoration efforts are in Florida, for the fast-growing staghorn and elkhorn Acropora coral species (the same ones that nearly died out across the Caribbean in 1970s). The Coral Restoration Foundation has led this effort since 2007. To date, the foundation has transplanted over 100,000 coral fragments onto the Florida Reef Tract (www.coralrestoration.org). Coral nurseries in Puerto Rico and the Virgin Islands have also successfully transplanted tens of thousands of coral fragments [79]. Mote Marine Laboratory and Aquarium (www.mote.org), in addition to managing their own underwater coral nursery, has built upon this effort in recent years by developing a method to micro-fragment and fuse typically slower growing corals, thereby speeding up the cultivation process for other species [80].
While increasing asexual reproduction on reefs can help maintain coral populations, only sexual reproduction can generate new genetic diversity. SECORE International (www. secore.org) is leading global coral restoration efforts by regularly producing millions of coral offspring from naturally released eggs and sperm. Once these newborn corals attach to tiles, they are transplanted onto a natural reef, where in time they can mature and contribute to the next generation [81,82]. However, restoration success (having transplanted colonies grow and sexually reproduce) is contingent upon the environmental conditions being suitable for corals, since stressors such as poor water quality can significantly reduce fertilization [83,84] and subsequent bleaching can kill transplanted colonies. Increasing the efficiency of coral restoration, e.g. by transplanting coral colonies that are mostly likely to survive and reproduce, in conjunction with improving local environmental conditions will help managers meet the challenges of continued coral population declines [85].

NOAA Fisheries
The primary law guiding the conservation and sustainable management of U.S. marine fisheries. The Act also protects fish habitat, which includes tropical coral reefs in the Western Pacific, Gulf of Mexico, South Atlantic, and Caribbean regions.

NOAA, U.S. Coast Guard
Regulates the negative effects of marine debris, defined as "any persistent solid material that is manufactured or processed," on the marine environment. Requires all federal agencies to prepare Environmental Assessments and/or Environmental Impact Statements to determine how their proposed actions may adversely affect the environment, and whether there are reasonable alternatives to the agency actions. The type of statement required depends on whether significant environmental effects will be caused by the federal action.

Army Corps of Engineers
Requires permits for the creation of structures in navigable waters of the United States, including bridges, piers, jetties, and breakwaters. The permitting process is subject to public review, through which any potential harm to beneficial ecosystems like coral reefs must be assessed. Shore Protection Act(100 U.S.C. § § 2601-2609, 1988)

Department of Transportation
Prevents the disposal of municipal and commercial waste in U.S. coastal waters, including territorial seas. Any vessel that must transport this potentially harmful material must obtain a permit from the Secretary of Transportation.

Stressor Policy Tools Example Gaps in Implementation
Coastal development Stricter regulation of coastal development and environmental remediation [86] Many public and private, as well as national and regional, interests are in conflict with regard to coastal development regulation. For example, in the U.S. Territory of Guam, the proposed military expansion of Apra Harbor would destroy tens of acres of coral reefs, some with 90% coral cover, despite significant backlash from the U.S. Environmental Protection Agency (Commander Navy Region Marianas, 2007). In general, the U.S. is lacking in environmental regulations and programs that mitigate impacts from development, with notable issues in the provisions for environmental impact assessments and statements (EIA/S). These EIA/S are meant to impartially identify the risks of development in sensitive areas, but can be fraught with administrative shortcomings and conflicts-of-interest [87,88].

Insufficient management resources
Fees to support conservation [89] Palau's 2017 House Bill to introduce the Pristine Paradise Environmental Fee of $100 for every international departure, included in the airfare price for ease of management, actually represents a very effective use of this strategy. From each fee 47.5is allocated to the National Treasury, 10to the Fisheries Protection Trust, 12.5to the state treasuries, and 30to conservation efforts as a "Green Fee" (RPPL No. 10-02). On the other hand, the $25 Environmental/Infrastructure Impact Fee introduced in the U.S. Virgin Islands earmarks nothing for environmental protection, instead allocating %15 to the V.I. Tourism Advertising Revolving Fund and 85% to the Territory's General Fund (The Virgin Islands Revenue Enhancement and Economic Recovery Act of 2017). Increased coastal nutrient input and pollution Improvements to wastewater management and infrastructure [90,91] Approximately half of the sewer lines in the U.S. are past the midpoint of their life cycle (U.S. EPA, 2002). President Trump proposed infrastructure plans that included financing for major water infrastructure development (The White House 2018, 2020). However, President Trump and Democratic congressional leaders they struggled to identify funding sources and were unable to enact legislation [92]. On January 14, 2019, Congress passed the bipartisan Water Infrastructure and Improvement Act (WIIA) (HR 7279) which amends the Clean Water Act (CWA) to include the 2012 Integrated Municipal Stormwater and Wastewater Planning Approach Framework, providing specific guidelines and a framework for evaluation, giving a comprehensive voluntary path for municipalities to meet CWA requirements.

Increased coastal nutrient input and pollution [cont.]
More stringent limits on coastal runoff [86] with mechanisms for enforcement [93] WaterWorks 2011, a $740-million initiative to overhaul Fort Lauderdale's water, wastewater, and sewer infrastructure successfully reduced levels of rainfall-induced and groundwater-induced infiltration [94]. However, continuous sewage line failures have kept the city under scrutiny, as pipe failures released as many as 211.6 million gallons of sewage into waterways and streets in a period of two months. Additional policy actions have been undertaken to address this gap, though their success remains to be seen: • In 2017, the Florida Legislature codified a Public Notice of Pollution requirement, which mandates notification of spills of unlawful substances within 24 hours, allowing authorities to respond more quickly to incidents (Chapter 403 Despite the benefits restoration can offer at a local scale, the pace of climate change is beyond what most corals can handle. Novel research initiatives exploring the possibilities of assisted evolution in corals and their algal symbionts ( Figure  3A), such as selective breeding for heat tolerance, continue to gain traction within science and management communities [2,95]. Other efforts to save coral diversity include genetic repositories (where live corals are maintained in aquaria or nurseries) and coral sperm banks through cryopreservation [96].
Recent initiatives have shifted focus from individual species to restoring and protecting entire reef ecosystems. NOAA recently launched Mission: Iconic Reefs, which targets seven reefs in the Florida Keys National Marine Sanctuary for multi-phased, active restoration. This will involve removing invasive species and algae, transplanting both fast and slow-growing coral species, and increasing the population of other beneficial species like sea urchins and Caribbean king crabs. Another unprecedented coral conservation project is the 50 Reefs Initiative (led by The Ocean Agency), which identified reefs likely to survive climate change and repopulate nearby reefs once the climate stabilizes [97]. The approach developed by the 50 Reefs Initiative will allow managers to maximize long term conservation benefits while reducing the risks of devoting limited resources to reefs that are unlikely to withstand projected warming and wave damage from increasingly intense cyclones [97].
Saving corals for the long term: Addressing climate change is our largest policy gap Even with these monumental restoration and conservation efforts, the predictions for climate change-driven coral reef loss are grim. The 2018 IPCC report warned that 1.5 • C increase in global temperatures would correspond to 70-90% coral reef decline, and a 2 • C rise could result in the loss of greater than 99% of reefs [98]. Aggressive international and domestic commitments to reduce greenhouse gas emissions are necessary if coral reefs are to remain functional ecosystems for the benefit of future generations. We, therefore, find it critical to highlight major policies and agreements surrounding greenhouse gas emissions.
The Clean Air Act (42 U.S.C. § 7401, 1963) [101]. Similar carbon markets already exist in the U.S., but only a small minority of states participate [102,103], limiting realized emission reductions due to the transfer of electricity generation to unregulated sectors [104].
Despite these federal decisions to abstain from strong action against the root cause of climate change, many states have made their own commitments to reduce greenhouse gas emissions consistent with the Paris Agreement. The United States Climate Alliance was formed in response to the impending U.S. withdrawal from the agreement, and includes 24 states and Puerto Rico. The U.S. governors in the alliance have promised to enact policies that reduce emissions 26-28% below 2005 levels by 2025, track and report progress to the international community, and promote clean energy within their states.

Conclusion
Coral reefs are one of our planet's most valuable ecosystems [5]. The coastal protection, tourism revenue, biodiversity services, and drug discovery potential of coral reefs are worth trillions of dollars annually [105]. The continued loss of coral reef habitat will represent a significant economic cost to many countries around the world, including the U.S.. The recent actions taken by the U.S. government in national and international policy arenas fall short of an effective strategy to address the greatest global threat to reefs: climate change resulting from increased greenhouse gas emissions. As a country with the second highest annual emissions and the highest cumulative emissions since 1751 [100], the U.S. should take a leading role in the battle against climate change, thereby helping preserve coral reefs for current and future generations. Local management efforts should prioritize the protection of coral reef habitats and strive to mitigate local stressors as much as possible. However, a national and international effort to limit the main source of coral death -increasing global temperatures -is imperative for the future survival of these vibrant marine ecosystems.

Citation
Rivera, H. E., Chan, A. N. & Luu, V. Coral reefs are critical for our food supply, tourism, and ocean health. We can protect them from climate change. MIT Science Policy Review 1, 18-33 (2020).

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