Editing Geography of Tuvalu (section)

===Environment – climate change issues===
{{Main|Climate change in Tuvalu}}
Since there are no streams or rivers and groundwater is not potable, most water needs must be met by catchment systems with storage facilities; beachhead erosion because of the use of sand for building materials; excessive clearance of forest undergrowth for use as fuel; damage to coral reefs from the bleaching of the coral as a consequence of the increase of the ocean temperatures and acidification from increased levels of carbon dioxide; Tuvalu is very concerned about global increases in greenhouse gas emissions and their effect on rising sea levels, which threaten the country's underground water table. Tuvalu has adopted a national plan of action as the observable transformations over the last ten to fifteen years show Tuvaluans that there have been changes to the sea levels.<ref name=NAP>{{cite web| title=Tuvalu's National Adaptation Programme of Action|work=Department of Environment of Tuvalu |date=May 2007|url= http://unfccc.int/resource/docs/napa/tuv01.pdf|access-date=7 September 2015}}</ref>

Because of the low elevation, the islands that make up this nation are threatened by current and future [[sea level rise]].<ref name="Krales">{{cite web| first= Amelia Holowaty|last=Krales|url= http://green.blogs.nytimes.com/2011/10/18/as-danger-laps-at-its-shores-tuvalu-pleads-for-action/|title=As Danger Laps at Its Shores, Tuvalu Pleads for Action| date =18 October 2011|work= The New York Times – Green: A Blog about Energy and the Environment|access-date=24 October 2011}}</ref> The highest elevation is {{convert|4.6|m|ft}} above sea level on [[Niulakita]],<ref name="JL">{{cite journal|first=James|last=Lewis|title =Sea level rise: Some implications for Tuvalu |journal=The Environmentalist|volume=9|issue=4|pages=269–275| date =December 1989|doi=10.1007/BF02241827|s2cid=84796023 }}</ref> which gives Tuvalu the second-lowest maximum elevation of any country (after the [[Maldives]]). However, the highest elevations are typically in narrow storm dunes on the ocean side of the islands which are prone to over topping in tropical cyclones, such as occurred on [[Funafuti]] with [[Cyclone Bebe]].<ref name="bom2">{{cite book |last1=  |first1= |title= Tropical Cyclones in the Northern Australian Regions 1971–1972|url= |format= |accessdate=  |year=1975|publisher= Bureau of Meteorology, Australian Government Publishing Service |location= |language= |isbn=|oclc= |doi= |id= |page= |pages=|chapter=|quote= |bibcode= }}</ref>

[[File:Ocean side Funafuti.jpg|thumb|left|300px|Ocean side of [[Funafuti]] atoll showing the storm dunes, the highest point on the atoll.]]

Tuvalu is mainly composed of coral debris eroded from encircling reefs and pushed up onto the islands by winds and waves.<ref name="NG15">{{cite web| last = Warne | first = Kennedy | work= National Geographic  |title= Will Pacific Island Nations Disappear as Seas Rise? Maybe Not – Reef islands can grow and change shape as sediments shift, studies show |date =13 February 2015|url= http://news-beta.nationalgeographic.com/2015/02/150213-tuvalu-sopoaga-kench-kiribati-maldives-cyclone-marshall-islands/|archive-url= https://web.archive.org/web/20150214031223/http://news-beta.nationalgeographic.com/2015/02/150213-tuvalu-sopoaga-kench-kiribati-maldives-cyclone-marshall-islands/|url-status= dead|archive-date= 14 February 2015| access-date=14 February 2015}}</ref> Paul Kench at the [[University of Auckland]] in New Zealand and Arthur Webb at the [[South Pacific Applied Geoscience Commission]] in [[Fiji]] released a study in 2010 on the dynamic response of reef islands to sea level rise in the central Pacific. Tuvalu was mentioned in the study, and Webb and Kench found that seven islands in one of its nine atolls have spread by more than 3 per cent on average since the 1950s.<ref name="new-rep">{{cite magazine|first=Bradford |last=Plumer |title=Pacific Islands Defying Sea-Level Rise—For Now | date=7 June 2010 |url=https://newrepublic.com/blog/the-vine/75348/pacific-islands-defying-sea-level-rise-least-now |magazine= New Republic |access-date=11 October 2015}}</ref> One island, [[Funamanu]], gained 0.44 hectares, or nearly 30 per cent of its previous area. In contrast, [[Tepuka Vili Vili]] has suffered a net loss in area of 22 percent since 1896. The shape and orientation of the reef has also changed over time.<ref name="NG15"/>

Further research by Kench et al., published in 2018 identifies rising sea levels as creating an increased transfer of wave energy across the reef surfaces of the atolls of Tuvalu, which shifts sand, resulting in accretion to island shorelines. Over 4 decades, there had been a net increase in land area of the islets of 73.5 ha (2.9%), although the changes are not uniform, with 74% increasing and 27% decreasing in size.<ref name="PSK"/> However, this process does not result in additional habitable land.<ref name="ktm519"/>

The storm surge resulting from a [[tropical cyclone]] can dramatically shift coral debris. In 1972 Funafuti was in the path of [[Cyclone Bebe]]. Tropical Cyclone Bebe was a pre-season [[tropical cyclone]] that impacted the [[Gilbert Islands|Gilbert]], [[Tuvalu|Ellice Islands]], and [[Fiji]] island groups.<ref name="BOM1975">Bureau of Meteorology (1975) ''Tropical Cyclones in the Northern Australian Regions 1971–1972'' Australian Government Publishing Service</ref> The storm surge created a wall of coral rubble along the ocean side of [[Fongafale]] and [[Funafala]] that was about {{convert|10|mi}} long, and about {{convert|10|to|20|ft|m}} thick at the bottom.<ref name="HB72">{{cite web |last=Resture|first= Jane|title= Hurricane Bebe 1972 |url= http://www.janeresture.com/hurribebe/hurricanebebe2.htm|date=5 October 2009 |work= Tuvalu and the Hurricanes: 'The Hurricane in Funafuti, Tuvalu' by Pasefika Falani (Pacific Frank)|access-date=15 February 2015}}</ref> The cyclone knocked down about 90% of the houses and trees on Funafuti and contaminated sources of drinking water as a result of the system's storm surge and fresh water flooding.

Tuvalu is affected by [[perigean spring tide]] events which raise the sea level higher than a normal [[high tide]].<ref name="BBC">{{cite news|first=David|last=Shukman|title=Tuvalu struggles to hold back tide|date=22 January 2008|work=[[BBC News]] |url=http://news.bbc.co.uk/2/hi/science/nature/7203313.stm|access-date=5 August 2008}}</ref> The highest peak tide recorded by the [[Tuvalu Meteorological Service]] was {{convert|3.4|m|ft}} on 24 February 2006 and again on 19 February 2015.<ref>{{cite web|publisher=[[Radio New Zealand]] |date=24 February 2015|access-date=17 March 2015|title=Tuvalu surveys road damage after king tides|url=http://www.radionz.co.nz/international/pacific-news/266995/tuvalu-surveys-road-damage-after-king-tides}}</ref> As a result of historical sea level rise, the [[king tide]] events lead to flooding of low-lying areas, which is compounded when sea levels are further raised by [[La Niña]] effects or local storms and waves.<ref name="PDV-24-2-15">{{cite news |last1= Eliuta|first1= Niuone |title= Science says Tuvalu will drown within decades; the reality is worse |url=https://devpolicy.org/science-says-tuvalu-will-drown-within-decades-the-reality-is-worse-20240215/ |access-date=15 February 2024 |work=PolicyDevBlog|date=15 February 2024}}</ref> In the future, sea level rise may threaten to submerge the nation entirely as it is estimated that a sea level rise of {{convert|20|–|40|cm|in|abbr=off}} in the next 100 years could make Tuvalu uninhabitable.<ref name ="Patel">{{cite journal | vauthors = Patel SS | year = 2006 | title = A sinking feeling | url = http://www.scidev.net/pdffiles/nature/tuvalu.pdf | journal = Nature | volume = 440 | issue = 7085| pages = 734–736 | doi = 10.1038/440734a | pmid = 16598226 | bibcode = 2006Natur.440..734P | s2cid = 1174790 }}</ref><ref name="staff.acecrc.org.au">Hunter, J. A. 2002. [http://staff.acecrc.org.au/~johunter/tuvalu.pdf Note on Relative Sea Level Change at Funafuti, Tuvalu] {{webarchive |url=https://web.archive.org/web/20111007232502/http://staff.acecrc.org.au/~johunter/tuvalu.pdf |date=7 October 2011 }}. Retrieved 13 May 2006.</ref>

Tuvalu experiences westerly gales and heavy rain from October to March – the period that is known as ''Tau-o-lalo''; with tropical temperatures moderated by easterly winds from April to November. Drinking water is mostly obtained from rainwater collected on roofs and stored in tanks; these systems are often poorly maintained, resulting in lack of water.<ref name="PAK">{{cite web|first=P.A. |last=Kingston |title=Surveillance of Drinking Water Quality in the Pacific Islands: Situation Analysis and Needs Assessment |year=2004 |url=https://pacific-data.sprep.org/dataset/drinking-water-quality-pacific-island-countries/resource/43881d9e-831b-488e-b0a5 |work=Situation Analysis and Needs Assessment, Country Reports, WHO |access-date=2 January 2020}}</ref> Aid programs of Australia and the European Union have been directed to improving the storage capacity on Funafuti and in the outer islands.<ref name="10EDF">{{cite web|url=https://ec.europa.eu/europeaid/countries/tuvalu_en|title=Tuvalu – 10th European Development Fund|work=Delegation of the European Union|access-date=2 January 2020}}</ref>