Tropical Cyclones and Coral Reefs Under a Changing Climate: Prospects and Likely Synergies Between Future High-Energy Storms and Other Acute and Chronic Coral Reef Stressors

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is a good viewpoint integrating an impact of tropical cyclones into synergistic influence of natural and anthropogenic stressors on shallow-water tropical coral reefs. In general, the paper is well written and informative. I believe it can be published in “Sustainability” after a minor addition on reef recovery rates following disturbances caused by TCs. It can take from 10 to 25 years (see Connell, 1997 [Coral Reefs, 1997, 16: S101–S113]) although complete recovery may in some cases require significantly more time: from 40 years in the case of exponential development to 70 years in the case of linear development (see Dollar and Tribble, 1993 [Coral Reefs, 1993, 12: 223–233]). Here the author may discuss these rates in the lite of global climate change with all corresponding stressors mentioned in his manuscript. Moreover, it should be noted that TCs accompanied with heavy rains and increased freshwater runoffs under conditions of global ocean acidification may lead to frequent periods of a significant local decrease in aragonite saturation with peak values Ωarag < 1, (see Manzello et al. 2013; https://doi.org/10.1002/jgrc.20378).

Author Response

Comment 1: This is a good viewpoint integrating an impact of tropical cyclones into synergistic influence of natural and anthropogenic stressors on shallow-water tropical coral reefs. In general, the paper is well written and informative. I believe it can be published in “Sustainability” after a minor addition on reef recovery rates following disturbances caused by TCs. It can take from 10 to 25 years (see Connell, 1997 [Coral Reefs, 1997, 16: S101–S113]) although complete recovery may in some cases require significantly more time: from 40 years in the case of exponential development to 70 years in the case of linear development (see Dollar and Tribble, 1993 [Coral Reefs, 1993, 12: 223–233]). Here the author may discuss these rates in the lite of global climate change with all corresponding stressors mentioned in his manuscript. Moreover, it should be noted that TCs accompanied with heavy rains and increased freshwater runoffs under conditions of global ocean acidification may lead to frequent periods of a significant local decrease in aragonite saturation with peak values Ωarag < 1, (see Manzello et al. 2013; https://doi.org/10.1002/jgrc.20378). Response: thank you. Recovery of reefs from TCs was raised by another reviewer and I have responded to it in the m/s with some more recent references "While some studies suggest that reefs can recover from hurricane damage within a decade or so [17, 19], this relies on the reefs having a certain level of intrinsic resilience. For example, while Jamaica's coral reefs initially showed some signs of recovery after Hurricane Allen in 1979 [31], by 2001 they had not fully rebounded to their pre-disturbance state, especially in terms of community structure [17]. Concerningly, the degraded state of these coral reefs was still evident, almost 40 years after Hurricane Allan [41]. That is highly likely due to impacts from later hurricanes coupled with chronic human impacts like nutrient and sediment runoff, diseases and overfishing, which has been said to have allowed a phase shift to macroalgae on many Jamaican coral reefs [41]." With regard to the fact that TCs accompanied with heavy rains and increased freshwater runoffs under conditions of global ocean acidification may lead to frequent periods of a significant local decrease in aragonite saturation with peak values Ωarag < 1, (see Manzello et al. 2013), I have added the text and ref to the m/s "When TCs are accompanied with heavy rains and increased freshwater runoffs under conditions of global ocean acidification [14], this may lead to frequent periods with a significant local decrease in aragonite saturation (Ω) states with peak values less than 1 [47]. The expected increase in the strength, frequency and rainfall of the most severe tropical cyclones with climate change (Table 1) in combination with ocean acidification will negatively impact the structural persistence of coral reefs beyond this century [47]."

Reviewer 2 Report

Comments and Suggestions for Authors

This is a review of the future variations of tropical cyclones and coral reefs in the context of global climate change. The viewpoint of the article is basically clear, and the logic is relatively reasonable. However, it is suggested that the authors further improve some aspects on the basis of collecting more literature, materials, and data.

(1) The rightmost column of Table 1 lists the theoretically predicted information on tropical cyclone changes. Then, what are the actual changes in the number and intensity of tropical cyclones, for example, in the recent several decades? That information better reflects the true situation we are facing.

(2) The title emphasizes both climatic and non-climatic coral reef stresses. However, in Figure 2, it is not evident whether there are climatic and non-climatic stresses, nor is there any difference between the two types of stresses.

(3) Section 2.2 should provide some figures to illustrate how tropical cyclones affect coral reefs. From the title of the paper, this is a core aspect. However, Section 2.2 only cites Figure 2 multiple times. Figure 2 does not illustrate this point. Moreover, tropical cyclones are not even the main focus in Figure 2.

(4) The future changes of tropical cyclones are also a key focus, and some visual figures should be provided. Section 3.1 repeatedly cites Figure 1 and Table 1, which appear monotonous, and the results are not intuitive.

(5) The paper mainly attributes the changes in tropical cyclones and coral reefs to greenhouse gas emissions. Therefore, the relationship between greenhouse gas emissions and tropical cyclones and coral reefs should also be specifically reviewed.

(6) The numbering of Sections 3 and 4 is incorrect.

Author Response

Comment 1: The rightmost column of Table 1 lists the theoretically predicted information on tropical cyclone changes. Then, what are the actual changes in the number and intensity of tropical cyclones, for example, in the recent several decades? That information better reflects the true situation we are facing. Response: This is an excellent suggestion. I have added this historical (last 30 years) information to the column second from the right.

Comment 2: The title emphasizes both climatic and non-climatic coral reef stresses. However, in Figure 2, it is not evident whether there are climatic and non-climatic stresses, nor is there any difference between the two types of stresses. Response: I have changed the title of the Opinion article to emphasise acute and chronic stressors.

Comment 3: Section 2.2 should provide some figures to illustrate how tropical cyclones affect coral reefs. From the title of the paper, this is a core aspect. However, Section 2.2 only cites Figure 2 multiple times. Figure 2 does not illustrate this point. Moreover, tropical cyclones are not even the main focus in Figure 2. Response: Other reviewers also made this observation and I have added more text about the impacts of TCs on coral reefs. I believe this has improved the Opinion article. I have removed unnecessary references to Figure 2 in the text.

Comment 4: The future changes of tropical cyclones are also a key focus, and some visual figures should be provided. Section 3.1 repeatedly cites Figure 1 and Table 1, which appear monotonous, and the results are not intuitive. Response: other reviewers also raised this concern and more explanatory text has been added. I have removed unnecessary references to Figure 2 and Table 1 in the text. Given word limits for Opinion articles I do not believe that any new figures are required.

Comment 5. The paper mainly attributes the changes in tropical cyclones and coral reefs to greenhouse gas emissions. Therefore, the relationship between greenhouse gas emissions and tropical cyclones and coral reefs should also be specifically reviewed. Response: The additional text provided in the revised version make the link between rising greenhouse has emissions, TCs and coral reefs much clearer.

Comment 6: The numbering of Sections 3 and 4 is incorrect. Response: corrected.

 

 

 

 

Reviewer 3 Report

Comments and Suggestions for Authors

Line 12  Good to define the abbreviation on first use.  But I would recommend not using abbreviations in abstracts.  That used to be the standard, though obviously some people do that these days.  I’ve even seen references in abstracts.

Line 31.  I don’t have that Knowlton reference 1 handy, but that figure of 3000 corals is quite wrong.  Even if you include corals that don’t have algae and live in dark, deep water, you won’t get much above 1500.  There are less than 900 reef building coral species known (831 is one present count.  www.coralsoftheworld.org).  It will go up, but that's the present count.

Line 38  for fishing 5 is the reference not 4

Line 40  I just searched the Woodhead article for “sequestration” and found nothing.  In addition, growth coral reefs does not remove CO2 from the atmosphere, counter-intuitively it adds it.  Ware et al have spelled this out.  Ware, J.R., Smith, S.V. & Reaka-Kudla, M.L. Coral reefs: sources or sinks of atmospheric CO₂?. Coral Reefs 11, 127–130 (1992).

Line 47  Global warming does not drive acidification.  The latter comes from CO2 in the atmosphere dissolving in ocean water reducing pH.

Line 60  Earthquakes and volcanic eruptions do not produce high energy storm events.  Earthquakes can (but often do not) produce tsunamis, which are destructive, but are not storms, storms are in the air, and tsunamis are water events.

Line 129  The most classical and seminal paper describing tropical cyclone damage on coral reefs is Woodley, E. A. et al. 1981. Hurricane Allen's impact on Jamaican coral reefs. Science 214: 749-755.  It is a glaring omission.

Another reference to consider might be Fenner, D. P. 1991. Effects of Hurricane Gilbert on coral reefs, fishes and sponges at  Cozumel, Mexico. Bulletin of Marine Science 48: 719-730.

Line 130, they do have a high resilience to TC damage, but low resistance to them, if the eye hits them, the waves smash them.

Line 169  I seriously doubt that those other human impacts have much effect on the destruction of coral produced by TC’s.  It is an almost entirely physical process of breakage.  About the only thing I can think of that might increase breakage might be weakening of coral skeletons and/or substrate by acidification.  If you really think so, you’ll need references to back that up.  Would be good to have a reference to back up the other stressors slowing recovery.  A good example would be recovery from Hurricane Allen in Jamaica, 45 years on there still is no recovery.  That is highly likely due to chronic human impacts like nutrient and sediment runoff and overfishing, which has been said to have allowed a phase shift to macroalgae there.

It would be good to put in somewhere that the energy source for cyclones is the temperature difference between the ocean surface and the stratosphere.  It is the energy in the top maybe 60 feet of water that counts.  With warming ocean surfaces the energy source is increasing.

Line 281  Shouldn’t reduction of overfishing be included here?  It is rampant on coral reefs everywhere there are people within 300 miles or so, and there are very few reefs that aren’t overfished, at least for their large fish species.   Other reference for the problems of managing coral reef fisheries are Fenner, D. 2012.  Challenges for managing fisheries on diverse coral reefs.  Diversity 4(1): 105-160  and Fenner, D.  2014.  Fishing down the largest coral reef fish species.  Marine Pollution Bulletin. 84: 9-16.   

Line 296.  A lot of people are very enthusiastic about coral restoration.  It is easy to grow coral once they are up off the bottom, suspended, that is very successful.  BUT, there are great limitations.  For one, if the corals are planted out without removing the factors that were killing corals in the first place, like poor water quality, overfishing, crown of thorns outbreaks, etc, then the corals that are transplanted out have no better chance of survival and the effort and money is wasted.   There are great hurdles for coral restoration, one of the greatest is that it is labor-intensive and large projects are no more efficient than small.  There are something like 450 coral restoration projects around the world, and all put together, they have restored well less than 1 km2.  There are about 250,000 km2 of reefs in the world.  Both the US and Australia are spending about $100 million on coral restoration.  At least Australia is trying to find ways to scale up.  But it is highly likely that the effort and money spent will be wasted.  It is attractive because the corals grow so well when suspended.  Hughes, Terry P. et al. 2023. Principles for coral reef restoration in the Anthropocene.  One Earth, Volume 6, Issue 6, 656 – 665.  This paper and a bit of the caveats needs to be mentioned.

Line 303, but of course the people in the lowest economic level countries are emitting the least greenhouse gases, they are victims not perpetrators.  Those in the high emission countries that are developed, the US and EU, have emitted the most emissions over history, and China is now emitting twice as much as the US and India is following behind.  Those are the countries that have the greatest responsibility to act, but obviously the US government is working hard to increase emissions, and China is still building coal power plants in addition to renewable energy.  Countries have not pledged enough and they have not been meeting their pledges, and there is little sign that the world community will act on any of the things that need to be done.  People continue to do too little too late, and while the battle is not lost yet, there is little sign the world will rise to the challenge and do it in time.  You don’t have to say all those things, and many are unwilling to say what you say.  What you’re saying is good, love it.  But action is woefully inadequate with little sign of that changing fundamentally.

Line 315  And several papers (Hughes and others) have argued that the time between disturbance events has already shrunk and will shrink more, and when there is not enough time even for resilient reefs to recover, each disturbance will take coral cover lower in a ratchet-like one-way direction to coral reef destruction.  Birkeland, C. Ratcheting down the coral reefs. Bioscience 2004, 54, 1021–1027.

Line 329  decades or less.

Line 370  The same reference is in 17 and 33.

Line 430  CO₂

Author Response

Comment 1: Line 12 Good to define the abbreviation on first use. But I would recommend not using abbreviations in abstracts. That used to be the standard, though obviously some people do that these days. I’ve even seen references in abstracts. Response: I have removed abbreviations from the Abstract.

Comment 2: Line 31. I don’t have that Knowlton reference 1 handy, but that figure of 3000 corals is quite wrong. Even if you include corals that don’t have algae and live in dark, deep water, you won’t get much above 1500. There are less than 900 reef building coral species known (831 is one present count. www.coralsoftheworld.org). It will go up, but that's the present count. Response: Correct to "over 800 species of hard coral species".

Comment 3: Line 38 for fishing 5 is the reference not 4. Response: Corrected to ref #4. Comment 4: Line 40 I just searched the Woodhead article for “sequestration” and found nothing. In addition, growth coral reefs does not remove CO2 from the atmosphere, counter-intuitively it adds it. Ware et al have spelled this out. Ware, J.R., Smith, S.V. & Reaka-Kudla, M.L. Coral reefs: sources or sinks of atmospheric CO2?. Coral Reefs 11, 127–130 (1992). Response: I have removed reference to carbon sequestration from the text.

Comment 4: Line 47 Global warming does not drive acidification. The latter comes from CO2 in the atmosphere dissolving in ocean water reducing pH. Response: I have edited the text to "Threats to reefs are largely from global warming, driving increases in the frequency and intensity of marine heatwaves, other extreme climatic events, while rising concentrations of CO₂ from combustion of fossil fuels are increasing ocean acidification [10-11, 13-14]."

Comment 5: Line 60  Earthquakes and volcanic eruptions do not produce high energy storm events.  Earthquakes can (but often do not) produce tsunamis, which are destructive, but are not storms, storms are in the air, and tsunamis are water events. Response: I have edited the text to "Tropical cyclones (TCs) are the most significant high-energy storm (HES) events affecting coral reef ecosystems globally [17-19]. Infrequent geophysical phenomena, such as seismic-generated high energy waves from submarine earthquakes and volcanic eruptions can also damage coral reefs [20]."

Comment 6: Line 129  The most classical and seminal paper describing tropical cyclone damage on coral reefs is Woodley, E. A. et al. 1981. Hurricane Allen's impact on Jamaican coral reefs. Science 214: 749-755.  It is a glaring omission. Response: I have added Woodley et al. to the text.

Comment 7: Another reference to consider might be Fenner, D. P. 1991. Effects of Hurricane Gilbert on coral reefs, fishes and sponges at  Cozumel, Mexico. Bulletin of Marine Science 48: 719-730. Response: I have not included this optional reference, instead opting to provide a cross-section of references from different tropical basins around the world.

Comment 8: Line 130, they do have a high resilience to TC damage, but low resistance to them, if the eye hits them, the waves smash them. Response: I have edited the text to "In the absence of significant anthropogenic stressors (Figure 2), coral reefs generally have a high resilience to TC damage, but low resistance if the eye of a TC passes directly over them, delivering high energy waves [17-19]."

Comment 9: Line 169  I seriously doubt that those other human impacts have much effect on the destruction of coral produced by TC’s.  It is an almost entirely physical process of breakage.  About the only thing I can think of that might increase breakage might be weakening of coral skeletons and/or substrate by acidification.  If you really think so, you’ll need references to back that up.  Would be good to have a reference to back up the other stressors slowing recovery.  A good example would be recovery from Hurricane Allen in Jamaica, 45 years on there still is no recovery.  That is highly likely due to chronic human impacts like nutrient and sediment runoff and overfishing, which has been said to have allowed a phase shift to macroalgae there. Response: I have modified the text as follows "While some studies suggest that reefs can recover from hurricane damage within a decade or so [17, 19], this relies on the reefs having a certain level of intrinsic resilience. For example, while Jamaica's coral reefs initially showed some signs of recovery after Hurricane Allen in 1979 [31], by 2001 they had not fully rebounded to their pre-disturbance state, especially in terms of community structure [17]. Concerningly, the degraded state of these coral reefs was still evident, almost 40 years after Hurricane Allan [42]. That is highly likely due to impacts from later hurricanes coupled with chronic human impacts like nutrient and sediment runoff, diseases and overfishing, which has been said to have allowed a phase shift to macroalgae on many Jamaican coral reefs [42]."

Comment 10: It would be good to put in somewhere that the energy source for cyclones is the temperature difference between the ocean surface and the stratosphere.  It is the energy in the top maybe 60 feet of water that counts.  With warming ocean surfaces the energy source is increasing. Response: In several places in the manuscript I describe how rising greenhouse gases are driving up global atmospheric and ocean temperatures. The excess energy in the climate system is feeling more intense TCs and intense rainfall events associated with TCs.

Comment 11: Line 281  Shouldn’t reduction of overfishing be included here?  It is rampant on coral reefs everywhere there are people within 300 miles or so, and there are very few reefs that aren’t overfished, at least for their large fish species.   Other reference for the problems of managing coral reef fisheries are Fenner, D. 2012.  Challenges for managing fisheries on diverse coral reefs.  Diversity 4(1): 105-160  and Fenner, D.  2014.  Fishing down the largest coral reef fish species.  Marine Pollution Bulletin. 84: 9-16.   Response: I have added this sentence and both references "Reduction of overfishing on many coral reefs is rampant and must be addressed [51], especially for their large fish species [52]."

Comment 12: Line 296.  A lot of people are very enthusiastic about coral restoration.  It is easy to grow coral once they are up off the bottom, suspended, that is very successful.  BUT, there are great limitations.  For one, if the corals are planted out without removing the factors that were killing corals in the first place, like poor water quality, overfishing, crown of thorns outbreaks, etc, then the corals that are transplanted out have no better chance of survival and the effort and money is wasted.   There are great hurdles for coral restoration, one of the greatest is that it is labor-intensive and large projects are no more efficient than small.  There are something like 450 coral restoration projects around the world, and all put together, they have restored well less than 1 km2.  There are about 250,000 km2 of reefs in the world.  Both the US and Australia are spending about $100 million on coral restoration.  At least Australia is trying to find ways to scale up.  But it is highly likely that the effort and money spent will be wasted.  It is attractive because the corals grow so well when suspended.  Hughes, Terry P. et al. 2023. Principles for coral reef restoration in the Anthropocene.  One Earth, Volume 6, Issue 6, 656 – 665.  This paper and a bit of the caveats needs to be mentioned. Response: I have added this sentence and reference "However, coral restoration is not a panacea for safeguarding the survival of the world’s shallow warm water coral reefs in the Anthropocene. Coral reef restoration efforts in the face of climate change must acknowledge the scale and severity of the environmental crisis, prioritise climate action and adopt a holistic approach that addresses both ecological and social factors to achieve meaningful restoration [56]."

Comment 13: Line 303, but of course the people in the lowest economic level countries are emitting the least greenhouse gases, they are victims not perpetrators.  Those in the high emission countries that are developed, the US and EU, have emitted the most emissions over history, and China is now emitting twice as much as the US and India is following behind.  Those are the countries that have the greatest responsibility to act, but obviously the US government is working hard to increase emissions, and China is still building coal power plants in addition to renewable energy.  Countries have not pledged enough and they have not been meeting their pledges, and there is little sign that the world community will act on any of the things that need to be done.  People continue to do too little too late, and while the battle is not lost yet, there is little sign the world will rise to the challenge and do it in time.  You don’t have to say all those things, and many are unwilling to say what you say.  What you’re saying is good, love it.  But action is woefully inadequate with little sign of that changing fundamentally. Response: I agree, so have added a sentence "As matters currently stand, carbon reduction pledges from the high emitting countries are woefully inadequate with little sign of that changing fundamentally."

Comment 14: Line 315  And several papers (Hughes and others) have argued that the time between disturbance events has already shrunk and will shrink more, and when there is not enough time even for resilient reefs to recover, each disturbance will take coral cover lower in a ratchet-like one-way direction to coral reef destruction.  Birkeland, C. Ratcheting down the coral reefs. Bioscience 2004, 54, 1021–1027. Response: Agreed, so have added in a sentence and the reference "The biggest concern is the time between disturbance events has already shrunk and will shrink more, and when there is not enough time even for resilient reefs to recover, each disturbance will take coral cover lower in a ratchet-like one-way direction to coral reef destruction [51]. "

Comment 15: Line 329  decades or less. Response: Have amended to "the world's coral reefs could be irreversibly lost within decades or less."

Comment 16: Line 370  The same reference is in 17 and 33. Response: corrected in m/s and refs.

Comment 17: Line 430 CO₂  . Response: corrected in reference.

 

 

 

 

   

Reviewer 4 Report

Comments and Suggestions for Authors

My review is uploaded. I recommend acceptance pending major revision.

Comments for author File: Comments.pdf

Author Response

Comment 1: Table 1 lists “Typical TC characteristics for world 82 regions [19], and projected changes in TC characteristics for 2°C of global warming above 2020 levels [41].” -- Comments: This is a typical example of moving the goalposts. The author should use the canonical 1.5°C threshold, not the new threshold of 2°C. Since the 1.5°C threshold has already been crossed in 2024, the author should access observed data that are freely available to see if TC characteristics have changed over the entire period of instrumental records (almost a century) instead of relying on modeling forecasts that cannot be validated in principle. Response: The caption was incorrect on my part. It has now been corrected as follows " TC characteristics and their historical changes for world regions [19, 23], and projected changes in TC characteristics for 2°C of global warming, relative to 1986-2005 baseline conditions [43]." The column second to the right has been updated to include historical changes in TCs for the tropical basins where they occur.

Comment 2: 

Line 108: “Recently published evidence showed that globally TCs are intensifying more rapidly in recent decades [23], especially in the north Atlantic [26] and northwest Pacific basins [27]. At the same time, there has been general slowdown in the forward speed at which TCs move across Earth’s surface [28]. This brings an increased risk for prolonged periods of high wave energy and heavy rainfall for coral reefs and adjacent river basins in the path of TCs [16]. As the planet warms and the tropical atmosphere and oceans expand poleward, several studies have shown that the average location where TCs reach their peak intensity has also shifted poleward in both hemispheres [30]. – Comments: The oceans do not expand poleward. Moreover, the warm pools in Atlantic, Indian, and Pacific Oceans do not shift poleward. These warm pools are huge reservoirs of heat, and they serve as “feeding grounds” for tropical cyclones. Since these warm pools are quasi-stationary, there is no physical reason for tropical cyclones to shift their paths (tracks) poleward. Response: I have provided several independent peer-reviewed sources that demonstrate the expansion of the tropics, that is driving the poleward shift of the zones of peak intensity for TCs in both hemispheres (see also additional information in the column second from the right).

Comment 3: Line 144: “TCs often cause riverine flooding and increased runoff onto fringing and inshore reefs [16]. This runoff can carry sediments, pollutants and excess nutrients from land-based activities into the reef environment, adversely impacting corals and other marine life [16, 24]. The addition of freshwater river plumes from land runoff can change ocean salinity and further stress corals and other marine lifeforms on already cyclone-damaged reef areas [16, 25]. – Comments: Over the last several decades, numerous dams have been built across the middle and upper stretches of the Yangtze River (Changjiang) in China, upstream of the Three Gorges Dam (TGD) and Three Gorges Reservoir (TGR). The TGD/TGR and upstream dams and reservoirs drastically reduced the total amount of suspended matters (mostly silt) that Yangtze carries to the ocean. The riverine water is now much more transparent than in the past, which is highly beneficial for corals in the southern East China Sea (south of 30°N), Taiwan Strait, and northern South China Sea, where Yangtze waters are transported by the China Coastal Current. The same development (dam construction and reservoir impoundment) is taking place along two major rivers in the Indochina: Red River and Mekong. The amount of sediments transported by Red River to Bakbo Bay (Gulf of Tonkin) has been sharply reduced lately due to the construction of numerous dams and reservoirs. The dramatic reduction of sediment load transported to the sea by Red River and Mekong has been highly beneficial for coral reefs in the entire South China Sea.  Response: This is interesting. A reduction in sediment load from the Red River and Mekong Rivers, while potentially beneficial in some ways, is actually detrimental to coral reefs in the South China Sea. These rivers deliver vital nutrients and building materials to the coastal ecosystems, and a decrease in sediment supply leads to increased erosion, habitat loss, and reduced biodiversity. 

Comment 4: Line 183: “One comprehensive study considered modelled changes in TCs across six TC basins for a 2°C of global warming, relative to 1986–2005 conditions and based on the high RCP8.5 carbon emissions pathway [42].” – Comments: (1) This is just another example of moving the goalpost. The author should use the 1.5°C threshold and analyze meteorological data for the entire period of instrumental records (almost a century; at the very least, the ample, quality-controlled meteorological data since the 1957-58 International Geophysical Year should be used). (2) The RCP8.5 carbon emissions pathway is an extreme case. Its usage has been widely criticized in literature. Response: According to Climate Analytics (2024), despite an escalating climate crisis marked by unprecedented wildfires, storms, floods, and droughts, our annual global temperature update shows global warming projections for 2100 are flatlining, with no improvement since 2021. The aggregate effect of current policies set the world on a path toward 2.7°C of warming.

Comment 5: Line 201: “As the atmosphere and oceans warm with rising greenhouse gases from anthropogenic activities, rain intensity rates will certainly increase as a warm atmosphere can hold more moisture [23]. Hence, all six TC basins may expect an increase in rain rate events from TCs under global warming (Table 1).” – Comments: Meteorological and oceanographic data do not support the above conclusions. Any substantial (and sustained) increase in rain rate over the ocean would immediately result in a substantial reduction of sea surface salinity (SSS) that would be detected from Earth-orbiting satellites. With several SSS sensors aloft (Aquarius, SMAP, and SMOS) this signal would be reliably detected. Yet there were no reports to date to support the above conclusions. Response: As shown in the revised Table 1 (column second from the right), many TC basins are already showing an increase in rain rates associated with TCs. See also: https://www.science.org/doi/10.1126/science.adp0212

Comment 6: Line 209: “The majority (approximately 70–90%) of the world’s tropical coral reefs (Figure 1) are 209 projected to disappear at even low levels of warming of 1.5°C above the pre-industrial 210 (1850-1900) average [43].” – Comments: The report cited here [43] has been published in 2022 and is already outdated since the 1.5°C threshold has been reached in 2024. The report’s prediction of the disappearance of 70-90% of the world’s coral reefs has been vastly exaggerated and therefore has not materialized. Response: I have re-worded the text as follows: "The majority (approximately 70–90%) of the world’s tropical coral reefs (Figure 1) are projected to begin transiting to degraded states when average global warming exceeds 1.5° C above the pre-industrial (1850-1900) average [44]." I note that the 1.5° C permanent threshold will occur in the early 2030s, possibly sooner. 

Comment 7: Line 285: “To bolster coral resilience, it will be necessary to assist gene flow among coral populations located at the warmer edges of their current ranges and to trial the introduction of heat-resistant coral species, including the assisted translocation of thermally tolerant coral phenotypes to higher latitudes [48-49].” – Comments: This is another attempt at geoengineering, which is fraught with unintended (and unpredictable) consequences and therefore should be considered as unacceptable. Response: More explanatory text has been added to the revised m/s.

Comment 8: Line 297: “These ambitious planned adaptation strategies are not comprehensive, but they do provide a plausible range of options for application across many coral reef ecosystems around the world (Figure 1). Many are likely to be very costly and will rely on monetary and capacity-building support from highly developed countries. Ultimately, the future of the world’s shallow warm-water coral reefs is highly dependent on a rapid reduction global carbon emissions and unilateral cooperation from high-carbon emitting countries.” – Comments: The high-carbon emitting countries are not the highly developed countries. China and India are probably the best examples, followed by Vietnam, Philippines, Pakistan, Iran, Bangladesh, Indonesia, Thailand etc. China and Vietnam alone are building scores of coal-burning power plants. Even though they are using the best modern technologies, their combined CO2 imprint far eclipses the emissions from the U.S. and Europe, where coal is almost phased out. These countries’ main goal is to lift several hundred million people from poverty. These countries cannot bear the burden of costly measures aimed at a rapid reduction of global carbon emissions. Response: Historically, the USA, EU, and UK have produced most of the CO2 circulating in Earth's climate system today. CO2 has a long residence time in the atmosphere. The wealthy countries must play a major role in emissions reductions.

Comment 9: Line 303, then 318: “Meanwhile, achieving the necessary global reduction in carbon emissions remains highly elusive to hundreds of millions of mainly poor people, who rely on the health and vitality of these remarkable marine ecosystems for their livelihoods, and together face an increasingly insecure future…. human communities that depend on them for food, coastal protection, cultural identity and economic activity.” – Comments: The human communities cannot rely on artisanal fisheries in the coral reef ecosystems. These ecosystems cannot sustain the livelihoods of these poor communities. An example: Gulf of Lingayen (famous for coral reefs) in the Philippines. According to a FAO report in the late 1980s, this mid-size embayment was extensively fished by 7,000 fishing boats manned by 12,000 fishermen, each boat catching on average 1 kg of fish per day per fisherman. Response: Please note in the revised m/s a comment about rampant overfishing, especially of large species. I have edited the sentence "...human communities that depend on them for their livelihoods, ..."

 

 

   

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I have no further comments and support its publication.

Reviewer 4 Report

Comments and Suggestions for Authors

I recommend acceptance in present form.