It is appreciated that the manuscript idea is well-received. Text addressing such observation systems and their development might of course appear somewhat bureaucratic, but we do not agree that presenting the structure and its development based on work from so many institutions over more than 10 years is presented in a too bureaucratic way.

One of the overall outcomes of the SIOS work so far is indeed that the links between the environments/disciplines are not yet fully developed, which is as expected given the development phase SIOS has reached. But this is also identified as a clear gap in the manuscript, and recommendations on ways to improve the interdisciplinarity are included. 

Svalbard itself is a major research hub for the M/LTI community with a multitude of instrumentation dedicated to the field located on and around the archipelago, as discussed in the SIOS SESS reports.  If we are to understand the entire Earth System then we cannot treat the M/LTI region as inconsequential.  As discussed in line 244 - 'we must quantify and understand in detail all physical processes that ultimately warm the atmosphere'.  These processes must also include those effects which couple the upper and lower atmosphere, as discussed briefly in lines 254 - 259. 

The focus is on the outcome of the SESS reporting process within SIOS. As SIOS has only carried out 4 years of reporting by the time this first synthesis of the outcomes, there is a limited range of big science questions addressed. However, we do present and discuss the development of SIOS with a focus on observational capacity and opportunities on the ongoing physical changes that the location offers in terms of both ongoing climatic and derived environmental changes (ranging across all parts of the Earth System), as they have been presented in the first 40 SESS report chapters. We clearly argue why Svalbard is an important location for observing and thus studying both the actual climatic changes and their consequences on the environment, based on an introduction that argues why Svalbard is the Arctic hotspot for the ongoing climatic changes. The emphasize this, the majority of the introduction is devoted to presenting in more detail the ongoing climatic changes as they are studied so far for the Svalbard region.

It is not the idea to provide any overview of the extensive set of observations that is being collected in Svalbard in this paper. Instead, the general objective that has been pursued and that this work reports on is to develop a methodology to summarize the aspirations and interests of the scientific community operating in Svalbard which are found in the SESS reports. Thus, providing useful information to ensure that the action to promote the various scientific priorities and themes can consider the reality found in the field, providing the basis for more effective and cost-effective planning and development of both infrastructure and research projects. Therefore, the very detailed discussion of e.g. the lower atmospheric topics and their links to other environments are not included more than what is done in the original SESS report chapters.

Technical comments:

Figure 2 will be changed into different colours representing the different environments.

The two last references (Wilkinson et al., 2016) and (Zhang et al., 2016) have fallen out of the uploaded technically revised manuscript, and will be added during revision of the manuscript. The Moreno-Ibáñez M.,et al. 2021 reference is in the reference list, but an open line has fallen out of the reference list, so that this reference has become part of the previous reference (Meredith et al., 2019). The line between the two references will be added in the revised text. The Cnossen (2020) reference is in the text in line 220.

Our manuscript does not aim for giving an overview of a new system for coordinating science and infrastructure in Svalbard. We rather synthesize the work with developing the Svalbard Integrated Earth Observing System.

1. We are not providing a review of the existing science as a background. This is because our aim is to present a synthesis of the development of the Svalbard Integrated Earth Observing System in its first years of full operation. And therefore, we focus solely in the introduction on presenting the changes going on in the climate system largely controlling the Earth System, but also review the overall effects on the environment in the remaining part of the Earth System.
2. The introduction is presenting in detail the most recent research documenting that the warming in the Svalbard area/region of the Arctic is the largest going on now.
3. We do not think that it is necessary to mention the history of Svalbard science coordination, but state that prior to SIOS collaboration of the magnitude of SIOS did not exist, which is a fact. NySMAC is a collaboration forum for exchange of information about research in a specific location Ny-Ålesund in Svalbard. It is not a joint long-term project with funding to build and share infrastructure and data like SIOS. NySMAC still exists, but cannot and will never replace SIOS. Due to the operational nature of NySMAC, it has never produced any gap analysis like what we present for SIOS.
4. We are happy to add a link in an appendix to the SIOS webpage, in which the 29 research institutes are listed.
5. The SIOS data catalogue that we refer to is found at https://sios-svalbard.org/metsis/search and contains numerous datasets covering a period beyond 2018. The longest datasets available on the data catalogue date back to 01/01/1945. The mentioned catalogue at https://sios-svalbard.org/sios-ri-catalogue serves a different purpose, and provides an overview of the observation facilities that collect SIOS data and also includes facilities that have ceased operation as well as planned upcoming observation facilities.
6. We are happy to add the link to the SIOS webpage as part of this manuscript in the revision, either directly in the text or in an appendix.

Our manuscript does mention that SIOS build on a unique and strong international collaboration, and this would not be possible if SIOS did not receive significant national and institutional funding from the 10 different countries that the 29 members come from. SIOS itself offering coordinated funding which goes across members, thus developing coordination between the members on infrastructure development.

Minor comments:

• The three inset maps in Figure 2 will be labelled with their overall location names of Longyearbyen, Hornsund and Ny-Ålesund in the revised manuscript.
• There is a strong focus on the overall atmospheric influence on the rest of the environments, and in an overview manuscript like this one, we did not find it relevant to add more details on the surface energy balance. It is, however, addressed indirectly in several places as there is a focus on snow, precipitation and black carbon.
• The push to increase the number of parameters being observed by AWS is mentioned especially for eastern and northern Svalbard, where only basic AWS infrastructure existed at the time of the SESS reporting. This implies that new technological developments are required with respect to sensors as well as green power supply systems. And so, we agree that it would be best if all AWS were measuring the exact same parameters, but given the present logistics of the observation infrastructure (access to power supply and power types and thus consistency of power access) it is not possible to measure as many and especially power demanding parameters in remote location in particularly eastern and northern Svalbard. It would of course be very nice if the number of AWS and thus the density of this type of basic infrastructure could be increased. This can however be challenging due to both logistics and the required permissions to establish infrastructure in the many protected areas in Svalbard.

We are not planning to increase the historical and science background information as this is not the scope of this manuscript.

We agree that the content of Table 1 is a very important part of the manuscript. The content of Table 1 forms the basis of the text in the sections 3.1 with its four environment specific subsections. So, we do therefore not think that it is necessary, nor relevant, to add more sentences to the overall themes listed in Table 1. Adding more text to this table might easily prevent the overview intended with this table presentation.