Tourism impacts and climate change stressors are on course to greatly affect Yellowstone, Mesa Verde, the Statue of Liberty and other UNESCO World Heritage Sites, according to a UNESCO report.

"At its best, tourism drives economic development and brings needed financial and social benefits, but, as this report demonstrates, rapid or unplanned tourism developments, or excessive visitor numbers, can also have a negative effect on the properties," reads the report's foreword. "Climate change is likely to exacerbate existing stresses and bring direct impacts of its own. Sea-level rise, higher temperatures, habitat shifts and more frequent extreme weather events such as storms, floods and droughts, all have the potential to rapidly and permanently change or degrade the very attributes that make World Heritage sites such popular tourist destinations.

"... The need to act is both urgent and clear."

In a series of case studies, from Bwindi Impenetrable National Park in Uganda and Komodo National Park in Indonesia to Yellowstone the report lays out how tourism and climate change can combine to exact significant impacts on these World Heritage Sites.

On Yellowstone, the report states:

How big the changes to Yellowstone will be depends partly on the rate of warming – climate models predict that warming during the next 100 years could be equivalent to that which occurred in the 12 000 years since the last ice age. Ann Rodman, a senior park scientist, says that “this is bigger than anything we’ve ever faced … the potential is out there to affect everything you see when you come to Yellowstone” (NPS 2015).

Warming is already causing winter in the park to become shorter, with less snowfall and snow staying on the ground less often. At the northeast entrance to the park, near Silver Gate, Montana, there are now many more days when temperatures rise above freezing every year than there were during the mid-1980s. Seventy per cent of snow monitoring sites in the park showed a steep decline in snow from 1961 to 2012, and analysis of tree rings shows that there has been a severe decline in levels of Yellowstone snowfall in the early years of the 21st century when compared to the last 800 years.

... Yellowstone can be a useful indicator for climate impacts on large ecosystems. With good habitat connectivity it is well buffered from most other environmental stresses, but it will still change – probably quite extensively – under evolving climatic conditions, perhaps even losing some of its iconic species and landscape characteristics. Climate change impacts will undoubtedly alter the visitor experience though, and if there are more frequent closures for forest fires, reduced potential for fishing or loss of iconic species and landscape features, the tourism economy may suffer (Riginos et al. 2015). Yellowstone National Park will continue to draw millions of tourists a year for generations to come, but it can also provide a vital natural laboratory for the study of climate change, as well as an outdoor classroom in which to educate and engage visitors about the problem and its solutions.

As for the Statue of Liberty, the authors wrote:

A 2015 vulnerability analysis carried out by the US National Park Service on its coastal properties concluded that 100 per cent of the assets at Liberty National Monument are at “high exposure” risk from sea-level rise due to the extremely low elevation of the island and its vulnerability to storms. The assets at risk on Liberty and Ellis Islands, including the Statue of Liberty itself, are valued at more than US$ 1.5 billion (Peek et al. 2015), but the intangible cost of future damage to this international symbol of freedom and democracy is incalculable. Hurricane Sandy’s damage to the infrastructure of the Statue of Liberty World Heritage site was extensive and tourism to one of the most popular attractions in the USA had to close for many months, but the lessons learned from its recovery can provide a model for other vulnerable coastal sites.

Regarding Mesa Verde National Park in Colorado, the report states:

Mesa Verde’s 4 500 archaeological sites are under severe threat of irreversible damage both from the increasing wildfires and from the flash floods and erosion that often follow. The vulnerability of Mesa Verde’s cultural assets to climate change could have a negative effect on tourism in the park, which attracts about 500 000 visitors a year contributing about US$ 47 million to the local economy. Damage to archaeological sites and the iconic cliff dwellings could change this, as could more frequent park closures due to large wildfires.

As for recommendations, the report suggests:

* The policy on responding to climate change adopted by the General Assembly of States Parties to the World Heritage Convention at its 16th session should be fully implemented.

* Identify those World Heritage sites most vulnerable to climate change and strengthen systems for continued assessment, monitoring and early warning of impacts.

* Make climate vulnerability assessment part of the World Heritage site nomination and inscription process.

* To strengthen resilience to climate change, increase the inclusion of wilderness areas on the World Heritage List, ensure connectivity between sites, and increase resources for protected area management.

* Urgently address the issue of inadequate resourcing for World Heritage site management and climate adaptation.

* Include cultural heritage in climate vulnerability assessments and policy responses at all levels, from the local to the international.

* Analyse archaeological data and cultural heritage to use what can be learned from past human responses to climatic change to increase climate resilience for the future.

Beyond that, the UNESCO report calls on government policymakers and the tourism industry to:

* Develop strategies and polices that lead to greenhouse gas emission reductions from the tourism sector that are in line with the goals of the Paris Agreement.

* Create detailed climate change action strategies for tourism management and development at vulnerable sites.

* Fully integrate climate change impacts and preparedness into national and site-level tourism planning, policies and strategies.

* Develop management tools for collecting data on tourism and climate impacts.

* Implement polices and action on climate change and tourism that are gender-responsive and participatory.

* Develop tourism investment guidelines that encourage inclusive and equitable development.