The Environmental Impacts of Overpopulation

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript is interesting and has some valuable synthesis of information from different sources. The author has covered most aspects of overpopulation its consequences to the health of our environment.

The major strengths of this work.

It has analysed an array of information dispersed widely in different areas from social sciences to biological sciences. It is generally difficult to combine these distinct areas and yet to present balanced views.

Major weaknesses of this work

The manuscript lacks figures, flow diagrams or other graphical descriptions of the content. There are also some overlapping interests of economy and ecology. This conflict is usually in favour the former. The authors may need to discuss the conflicting problems while searching for solutions. Many problems due to overpopulation do not remain national. Their consequences could as well be international. For example, the International Labour Organisation's Declaration of Philadelphia in 1944 that “poverty anywhere constitutes a danger to prosperity everywhere..” is valid even today. This is also applicable for pandemics, with recent worldwide sufferings from covid-19.

In addition, the manuscript would benefit from adding or emphasizing on the following aspects:

1. Overpopulation and world hunger. Search for new or rarely touched food resources such as wild forest animals with their diseases spreading to humans, e.g., covid-19
2. Inland waters availability and contamination and international water disputes
3. Increased sea trade across the globe and the transport of exotic animals, e.g., zebra mussel, which cause havoc to the local species
4. The possible remedial measure to control the adverse effects from overpopulation. For example, disputes for water, construction of dams etc., from different nations can be resolved through international courts or special inter-governmental commissions.
5. Surprisingly, the manuscript lacks any figures. Please provide figures for geographical regions with high percentage of deforestation etc. where relevant.

Author Response

Please see attached file

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper is very well written and clear. The attached pdf highlights some misspells.

Comments for author File: Comments.pdf

Author Response

Please see attached file

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This paper provides a reasonably fine overview of the role that overpopulation of humans plays in causing and exacerbating 6 global ecological challenges. However, there are numerous generally minor points that need correcting or addressing, including many editorial issues:

1. Regarding the overpopulation of humans, you might want to introduce and review Ehrlich & Holdren’s famous equation, IPAT (environmental impact = population x affluence x technology) and later alternatives. Many scholars  stress affluence or economic growth as the more important variable or a variable equally important to population, e.g. see Brian Czech et al. 2012. Effects of economic growth on biodiversity in the United States. Natural Resources Forum 36, 160-166.
2. Why did you choose the 6 “global ecological challenges” that you review, and not others, e.g. food waste, plastic pollution, particulate air pollution, the clean energy transition, stratospheric ozone loss, etc.?
3. Line 71 typo, “acknowledging” not “acknowledge”
4. Line 72 typo, “evidence” not “evience”
5. Line 152-155, it would be better to report the forest loss data in common units and easier for the reader to follow and compare
6. Line 168, needs a period at the end of sentence, not a comma.
7. Line 170, delete the period after “them”
8. Line 354, delete the comma after “as a”
9. Line 381, use lower case throughout in “invasive species”
10. Line 444 typo, “confirms” not “confirms”
11. Line 447, insert “PNG” abbreviation, or spell out the country name on line 453; if you abbreviate no need to spell it out again
12. Line 518, replace “annually” with "indefinitely” for MSY
13. Line 553, delete comma after “highlighting”
14. Line 557, delete comma after “sustenance”
15. Line 561 typo, “practices” not “pratcies”
16. Line 568, insert comma after “fish populations”
17. Lines 577 & 582, insert “human” before “population”
18. Line 591, delete the 2^nd use of “by”
19. Line 605, note that krill is not a fish species, it is a crustacean.
20. Lines 635-636, Syria is a prime example of a Middle Eastern country where water stresses have led to disastrous results.
21. Line 646, typo, “Scientific Reports” not “Science Reports”
22. Lines 726-732, note that there are over 100 definitions of desertification, and a combination of anthropogenic AND climate-induced changes contribute to the problem
23. Line 753, actually over 1360 exports contributed to the Millennium Ecosystem Assessment
24. Line 762, insert “of” before “desertification”
25. Line 772, insert “the” before “land’s”
26. Lines 804 & 808, “commons”, not “common”?
27. Line 829, delete the comma after “growth”
28. Lines 834-835, you refer to the critical “sustainability challenges” facing humanity, yet at the start of the paper you referred to six global “ecological challenges”. Which is it? These phrases mean different things.
29. Lines 842-843, you left out “water scarcity”; also, you alternatively describe 1 of your 6 big challenges as land degradation, desertification, and soil degradation. This is confusing, and it would be better if you used more consistent language in different parts of the paper.
30. Line 861, needs a comma instead of a period after “global crisis”

Author Response

Please see attached file

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

This is very well done and I believe will be well received.  

I think that the grammar needs to be checked and edited some but, otherwise, I see no problems.  

Author Response

Thank you.  Grammar has now been rechecked and improved. 

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript now reads better.

Reviewer 3 Report

Comments and Suggestions for Authors

The paper can now be accepted. I look forward to seeing the published version.