13. Climate Change and Adventure Tourism

By studying many different proxy data sources from places around the world, scientists have found evidence of global-scale climate change, from ice ages or glacial periods, when huge ice sheets covered most of Earth, to such as the present, when ice is largely confined to the polar and high mountain regions. According to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (2014), warming of the climate system is unequivocal. This is now evident from observations of increases in global average air and ocean temperatures that anthropogenically produced greenhouse gases (mainly carbon dioxide, CO₂) are contributing to the present warming of about 1.1 °C that has taken place since the late nineteenth century. Rising sea level is consistent with warming. Global average sea level has risen since 1961 at an average rate of 1.8 (1.3–2.3) mm per year, and since 1993 at 3.1 (2.4–3.8) mm per year, with thermal expansion, melting glaciers and ice caps, and the polar ice sheets contributing. Further warming will continue if emissions of greenhouse gases continue. The global surface temperature increase by the end of the twenty-first century is likely to exceed 1.5 °C relative to the 1850–1900 period for most scenarios and is likely to exceed 2.0 °C for many scenarios. The global water cycle will change, with increases in disparity between wet and dry regions, as well as wet and dry seasons, with some regional exceptions. The oceans will continue to warm, with heat extending to the deep ocean, affecting circulation patterns. Decreases are very likely in Arctic sea ice cover, northern hemisphere spring snow cover and global glacier volume. Global mean sea level will continue to rise at a rate very likely to exceed the rate of the past four decades. Changes in climate will cause an increase in the rate of CO₂ production. Increased uptake by the oceans will increase the acidification of the oceans. Future surface temperatures will be largely determined by cumulative CO₂, which means climate change will continue even if CO₂ emissions are stopped.