Impact of Climate Change on Biodiversity and Implications for Nature-Based Solutions

Reviewer 1

Revision authors

The methodology used in this manuscript, including study period (in terms of years) will be introduced shortly in the abstract section.

We have included the study period in the abstract. Moreover lines 140 to 160 of the Methodology is rephrased.

The abstract should include more quantitative results.

The following quantitative results are now included in the abstract:

“Our study indicates that North American and Oceanian sites with a humid continental and subtropical climates, respectively, are posed to realize temperature shifts that have been identified as a potential key tipping point trigger. Heat stress may significantly affect approximately 60%-90% of mammals, 50% of birds, and 50% of amphibians in North American and Oceanian sites for durations ranging from 5 to 84 days per year from 2080.”

No need to use different sub-headings under introduction section: 1.1. The Effects of Climate Change on Biodiversity, 1.2. Monitoring Bioclimatic Pressures in Nature Conservation, and 1.3. Problem Statement and Aim. The authors can introduce their topic under single heading as INTRODUCTION. Similarly, problem statement can be also addressed under introduction without separate sub-section.

We deleted all headings of the introduction section, as well the problem statement is addressed in third Alinea of Introduction section

Highlight the original aspects of the manuscript

The following explanation is given in L451-458:

“Previous studies have shown that the relative proportion of species threatened from the IUCN Red List in combination with IUCN predictors are relevant indicators to assess climate change effects on bioclimatic variables and on biodiversity. However, most studies were not conducted for NbS sites over multiple transects based on climate zones. In our study, the global IPCC climate projections are coupled to today’s IUCN biodiversity threats to enhance understanding in the effectiveness of application of NbS as a way for climate adaptation and biodiversity conservation.”

A conclusion section requires some improvements.

The Conclusion section is rephrased

Avoid the use of numbering in the conclusion section. You can shortly conclude your research findings within a paragraph.

The numbering in the conclusion section is removed.

Reviewer 2

Revision authors

I found the paper quite difficult to follow, and many of the methods are not explained sufficiently to evaluate the basis for the results. My overarching concerns are in xx categories: The introduction is difficult to follow, though things become clearer as the paper proceeds. For example, the title suggests the paper will look at the climate impacts of NbS, which doesn't make sense. I think what is intended is 'Bioclimatic impact on biodiversity and implications for Nature based Solutions and Resource Management', or something like that. Ecosystem also doesn't make sense in the title, given the lack of treatment of plants which are the foundation for all communities.

We have changed the title to “Bioclimatic impact on biodiversity and implications for Nature based Solutions”.

We have improved the writing of the introduction and we have shortened the introduction to make it better readable and easier to follow.

The paper was also difficult to understand without first reading Hielkema and Schipper (2023) (or is that Hielkema, Schipper, and Gersonius?).

After rephrasing, without having read Hielkema et al., 2023, the paper is now understandable. Also the reference is written consistently

L77 states that prior studies of climate impacts on biodiversity are based on 'expert judgment'. This vastly understates the extent of this literature. A google scholar search on 'biodiversity climate vulnerability' will just scratch the surface of the 100s of papers, many using quantitative methods based on physiology, species distribution, etc. I acknowledge that I am not familiar with the literature and approach in this paper, but even in that context, this paper seems to be quite disconnected from an extensive literature on the topic.

We have done an extensive literature study, as summarized in the introduction. In L77-L83 and L96-L97 and Appendix 1, we listed research that focused mostly on expert judgement. We have rephrased the text, to prevent confusion.

L103 makes sweeping assertions about a holistic approach to biodiversity, but in the end the paper is a fairly straightforward assessment of the sensitivity of a selected set of species (though see below), and this paragraph does not seem to contribute a great deal. 

There is a confusion about what we meant here. The sentence L103 is changed in ‘Within the scope of this paper, we consider biodiversity in the general sense, considering…...

There are numerous papers on climate vulnerability assessment for biodiversity - either ecosystems or species - that the authors seem to be unaware of. E.g.:

We have rephrased this part, L80:

“Readily applicable methodologies for evaluating biodiversity vulnerability levels to projected bioclimatic pressures, particularly those which can account for climate resilience solutions and adaptation strategies are available. However, to the best of our knowledge, existing literature has not attempted to conduct an analysis of NbS based on existing threats to biodiversity and long-term bioclimatic projections, the core application considered in this work”

The methods for selecting the study sites are not explained, except alignment with the earlier paper by the authors, 

The selection criteria of earlier work is extensive rephrased in the methodology from L123:

“The selection criteria for the NbS sites considered is primarily driven by a desire to maintain similarity and comparability between them. This has been based on their functionalities, namely flood protection, serving socioeconomic growth, intrinsic value of biodiversity and ecosystems, regulating emissions, erosion reduction and serving wellbeing of humans (Hielkema et al., 2023).”

the methods to determine what species were found at each site are not explained.

From L176 is written more in detail how to determine the species at each site:

“Local biodiversity threat profiles were produced based on the IUCN biodiversity threats spatial data and species’ thermal tolerance limits. Firstly, the IUCN provides spatial data for threatened species and the direct threats to species.“

(…)

“The IUCN data was modified in the same process as described by Bellard et al. (2015) and used to generate a spatial biodiversity sensitivity map. Following the IUCN species distribution data (IUCN, 2019), species were selected based on the overlap of their distribution with the coordinates of the NbS sites under consideration. Additionally, the species had to be scored as extant, native and resident, so that invasive species were excluded. This ensured that species not adapted to local climate conditions were not evaluated and did not skew the evaluation of native ecosystems. Ten key species groups were selected that play a central role in several ecosystem services, namely (…)”

It would be extremely helpful to demonstrate how the authors assessed sensitivity for exemplary species, as the foundation for the quantitative results across sites.

The sensitivity of species to different bioclimatic pressures is given by the IUCN and GlobTherm databases, that have collected data from many scientific papers. In our paper, we are focused on the level of species groups, biodiversity and ecosystems, rather than (exemplary) species. We do so to research the broader effects of climate change on NbS areas and NCM planning strategies.

In the beginning of the methods (from L139, and throughout the methodology section) the following is explained:

“In Step 2, present-day IUCN biodiversity threats are analyzed for the relevant climate zones to create a biodiversity sensitivity map which is then evaluated within the context of the IPCC projections under emissions scenarios SSP1-2.6 and SSP5-8.5. Furthermore, the GlobTherm data is analyzed to construct the Potentially Affected Fraction (PAF) of species groups to temperature extremes, using sigmoid shape Upper Thermal Tolerance Limit - Species Sensitivity Distribution (UTTL-SSD) response relationship (Posthuma et al., 2001; Schipper et al., 2010).”

Additionally, the results and discussion are framed as 'North America', 'Europe', and 'Oceania', when it is just a few sites in each area. The implication that the results generalize to continent scale is misleading and distracting. Throughout 'NbS' is used as a noun, refering to specific sites, which seems inappropriate. NbS is an approach to management. Perhaps the paper should refer to 'project sites' or 'NbS sites', and 'European sites', etc.

The wording is changed to NbS sites and European-, North American- and Oceanian sites.

While I was not previously familiar with GlobTherm, I am concerned about the analyses crossing scales from regional IPCC projections to organism level physiology. There are lots of ways that organisms will adjust to climate - phenological shifts mean they may be active at different times; habitat shifts into shaded microclimates can buffer from regional climate; and species migrations will shift the set of species at each site. All of these factors will potentially reduce impacts of the species actually found at a given site by the end of this century. Only on L466 is the absence of treatment of migration acknmowledged, but this is just one of many challenges downscaling from IPCC climate to organismal physiology. Work such as Porter (Proceedings of the National Academy of Sciences, 106(supplement_2), pp.19666-19672.) and Buckley (https://doi.org/10.1111/j.1461-0248.2010.01479.x) illustrate how behavioral and physiological models can be developed to address these challenges. 

We agree with you opinion that the interaction between organisms and their environment will affect the impact of extreme temperature on the individual. So, it requires knowledge of morphology, physiology, and behavior, as is also stated by several studies (Porter; Buckley; Kearney). The text is rephrased:   ’ ‘Mahecha et al. (2023) have suggested conservation plans need to explore the relationships between biodiversity and ecosystem dynamics in response to climate extremes to understand the implications of periodic extreme events’ disruption of systems. To do so, further emphasis is needed in developing or larger applications of predictive models that consider the interactions between atmospheric processes, behavioral and migration patterns and ecosystems.’ (…) Kearney, 2006; Chausson et al., 2020; Buckley et al., 2023).

L64 'toxicant sensitivity' seems to be quite a different topic, relevance here is not clear

There is a relationship between climate warming and the temperature-related sensitivity to toxins. However, we do agree that this relationship was not sufficiently explained. Also, the relevance to this paper is limited. Therefor we decided to remove this sentence.

Page 5 lists ten species groups, which do not include plants, though these are listed earlier in the paper

Plants was removed from the assessment, but section 1.2 was not yet changes accordingly (but now is).

L251: By definition a non parametric correlation does not test for linearity - only for a positive or negative relationship, with no specified shape

The sentence is corrected: “The Spearman correlation coefficient p is a measure for the strength and direction of monotonic association between two independent variables”

Fig. 2 - how many species in each group were evaluated? It's difficult to interpret the magnitude of impact based on absolute numbers without context.

In figure 2 the absolute numbers are added

Fig. 6 - what is the source of the information for building the food webs? Food webs are quite local - does it make sense to characterize them across all sites in each region?

Mentioned in chapter 2.3. ‘The effect of heat stress on an ecosystem as a whole can be simulated by integrating projected heat stress among species with food web interactions. Simplified food webs are constructed for East Australian, North American and West European NbS sites to simulate the predicted effects of temperature rise on various trophic levels, utilizing the species groups considered. The interactions are based on the percentage-estimates of species within a given species group which are threatened by heat stress, as shown in the UTTL-SSD-curves (Rayner et al., 2010; Boonstra et al., 2016).

Sect. 3.2.2 I don't understand what the two variables are for these correlations - please clarify

Here the IUCN and IPCC data are correlated, as explained in the fist sentence:
“The outcome from correlating the current biodiversity threats with the projections of changing bioclimatic pressures mean annual temperature, max-5-day precipitation and droughts (CCD) gives no clear positive correlations among all sites considered on a global scale (Appendix 9).”

The meaning of such correlations is explained in the last sentence:

“Positive correlations highlight an imbalance in the climate pressures of concern, where biodiversity in some sites per continent stand to be particularly vulnerable and exceptionally influenced under the considered projected intensifying climate conditions.”

To clarify this a bit more, the following example was added:

“For instance, in Europe drought is projected to intensify particularly in project sites where biodiversity shows sensitivity to droughts (rho (6) = .78, p = .06) – that is in Medway Catchment and Het Zwin.”

Appendix 1 is quite an idiosyncratic collection of citations. What is the intent - to show examples of biodiversity impact studies? To make generalizations by region?

Yes , the context is to generalize the impact studies by region. Added is the text at appendix 1 “Overview of climate change impact on biodiversity used to assess climate change impacts in geographical areas. Different policy strategies and abiotic factors are realized in, respectively, Asia, Africa, Europe, America, and Australia.”

Appendix 10 - What methods were used to make these assessments? How were species mapped to these polygons? Did you only assess species in the NbS study sites? It doesn't make sense to show a map of the world if no analyses were conducted for all of the gray colored polygons.

Since no analyses were conducted for all of the gray colored polygons, we have deleted appendix 10