{"id":17925,"date":"2021-02-23T06:32:16","date_gmt":"2021-02-22T21:32:16","guid":{"rendered":"https:\/\/coralreefpalau.org\/?page_id=17925"},"modified":"2021-02-27T13:48:53","modified_gmt":"2021-02-27T04:48:53","slug":"climate-change-in-palau","status":"publish","type":"page","link":"https:\/\/coralreefpalau.org\/projects\/climate-change-in-palau\/","title":{"rendered":"Climate Change in Palau"},"content":{"rendered":"

[vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”grid” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern” css=”.vc_custom_1494900031563{padding-top: 75px !important;padding-bottom: 75px !important;}”][vc_column][vc_single_image image=”15753″ img_size=”full” qode_css_animation=”” css=”.vc_custom_1491176500169{margin-bottom: 25px !important;}”][vc_column_text]<\/p>\n

Climate change in Palau<\/span><\/h3>\n

[\/vc_column_text][vc_column_text]Climate change has many complex layers, including the multiple factors that can affect weather patterns and the subsequent ecological impacts. Through this project, we work on making this information more accessible and easy to understand for the general audience. With information drawn from the 2020 Pacific Islands Regional Climate Assessment report<\/a>, the video presented provides simple and basic ideas at the elementary level behind climate change and its impact on Palau. This web page complements the video by providing a more in depth look at patterns of key parameters of climate change: sea temperature and sea level in Palau. Here, we focus on how climate change specifically affects Palau using a 20-year data set to look at short term variation of sea temperature and sea level in relation to ENSO events and overall long term trends.[\/vc_column_text][vc_empty_space height=”25px”][vc_video link=”https:\/\/www.youtube.com\/watch?v=TlME46RSFy4&feature=youtu.be”][\/vc_column][\/vc_row][vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern” el_id=”img-gallery” el_class=”h-gallery”][vc_column][vc_gallery type=”image_grid” images=”17964,17965,16703″ img_size=”full” column_number=”3″ grayscale=”no” images_space=”gallery_without_space”][\/vc_column][\/vc_row][vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”grid” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern” background_color=”#39a694″ css=”.vc_custom_1493948630977{padding-top: 100px !important;padding-bottom: 100px !important;}”][vc_column][vc_column_text el_class=”yellow-link-teal-bg”]<\/p>\n

El Ni\u00f1o and La Ni\u00f1a in Palau: El Ni\u00f1o\u2013Southern Oscillation (ENSO)<\/span><\/h3>\n

In Palau, located in the far western Pacific, ENSO extremes produce conditions that are different from other geographic areas of the central and eastern Pacific. Palau\u2019s local conditions relative to the ENSO phase are often misunderstood. El Ni\u00f1o produces hot ocean water in the far eastern Pacific, but very cool sea water temperatures in Palau. La Ni\u00f1a produces cool ocean water in the eastern Pacific, but very warm sea water temperatures in Palau. Sea level also differs dramatically in Palau between El Ni\u00f1o (low sea level) and La Ni\u00f1a (high sea level) episodes. Strong El Ni\u00f1o and La Ni\u00f1a events produce extreme conditions with dire consequences. Moderate and weak events produce less dramatic conditions. These El Ni\u00f1o and La Ni\u00f1a fluctuations in Palau are summarized below.<\/span>[\/vc_column_text][\/vc_column][\/vc_row][vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”grid” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern” css=”.vc_custom_1494900031563{padding-top: 75px !important;padding-bottom: 75px !important;}”][vc_column][vc_column_text][\/vc_column_text][qode_elements_holder number_of_columns=”two_columns”][qode_elements_holder_item vertical_alignment=”middle” advanced_animations=”no” item_padding=”0px 25px 0px 0px”][vc_column_text]El Ni\u00f1o<\/strong> \u2013 Low sea water temperatures (due to shallow thermoclines) and low mean sea level (MSL). This is generally good for corals and for Jellyfish Lake. However, extreme low mean sea levels can fatally expose shallow water corals to air. Strong El Ni\u00f1o events produce extreme droughts in Palau.[\/vc_column_text][\/qode_elements_holder_item][qode_elements_holder_item vertical_alignment=”middle” advanced_animations=”no”][vc_single_image image=”17953″ img_size=”full” onclick=”link_image” qode_css_animation=””][\/qode_elements_holder_item][\/qode_elements_holder][qode_elements_holder number_of_columns=”two_columns”][qode_elements_holder_item vertical_alignment=”middle” advanced_animations=”no”][vc_single_image image=”17956″ img_size=”full” onclick=”link_image” qode_css_animation=””][\/qode_elements_holder_item][qode_elements_holder_item vertical_alignment=”middle” advanced_animations=”no” item_padding=”0px 0px 0px 25px”][vc_column_text]La Ni\u00f1a<\/strong> \u2013 High sea water temperatures and high mean sea level (MSL). This can cause coral bleaching and mortality throughout the water column in an extreme event, and was the cause of the massive coral bleaching in Palau in 1998. Mean sea level is also high, but this does not adversely affect reefs through aerial exposure. Strong La Ni\u00f1a events can produce extreme amounts of rain, causing environmental damage.[\/vc_column_text][\/qode_elements_holder_item][\/qode_elements_holder][vc_column_text]Images reproduced by permission of Bureau of Meteorology, \u00a9 2017 Commonwealth of Australia<\/p>\n

In Palau, El Ni\u00f1o and La Ni\u00f1a variation occurs regularly and has effects on most physical parameters, including sea water temperature, mean sea level (MSL), amount of rain etc. This variation is integral to the marine environment and underlies much of the diversity of conditions which support the marine habitats of Palau. Let\u2019s take a look at some of these specific parameters.[\/vc_column_text][\/vc_column][\/vc_row][vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern” el_id=”img-gallery” el_class=”h-gallery”][vc_column][vc_gallery type=”image_grid” images=”17968,17969,17970″ img_size=”full” column_number=”3″ grayscale=”no” images_space=”gallery_without_space”][\/vc_column][\/vc_row][vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”grid” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern” background_color=”#39a694″ css=”.vc_custom_1493948630977{padding-top: 100px !important;padding-bottom: 100px !important;}”][vc_column][vc_column_text el_class=”yellow-link-teal-bg”]<\/p>\n

Mean Sea Temperature<\/span><\/h3>\n

Short Term Temperature Variation tied to ENSO<\/strong>
\nWhen looking at the mean sea water temperatures (for weeks, months and years) along the outer reef slopes of Palau, they show a highly variable environment with respect to temperature and depth, with ecological consequences. Much of the variation can be tied to ENSO conditions, El Ni\u00f1o and La Ni\u00f1a, cycling over intervals of several years. El Ni\u00f1o is associated with cool water temperatures both near the surface and at depths, such as in 2015-2016. La Ni\u00f1a has warm temperature along the entire reef slope, such as in 2010-2011. The red line shows the coral ‘bleaching threshold’ of 30.0\u00baC. Dotted lines show the trend lines of temperature at different depths. If only shallow depths (about 15-20 m) are considered, the variability is less, but still responds to ENSO conditions.<\/span>[\/vc_column_text][vc_empty_space height=”25px”][vc_single_image image=”17938″ img_size=”full” qode_css_animation=””][vc_empty_space height=”25px”][vc_column_text el_class=”yellow-link-teal-bg”][\/vc_column_text][vc_column_text el_class=”yellow-link-teal-bg”]Long Term Temperature<\/strong>
\nOver the last 20 years, temperatures on Palau\u2019s reefs have gradually increased at a rate of about 0.2-0.3\u00baC per decade (black line), rates which are close to the global rates of ocean temperature rise. Since 2010, there have been increasing occasions when shallow temperatures creep up above the 30\u00baC \u201cbleaching threshold\u201d (red line) for days to weeks. Unfortunately there is no comprehensive in situ<\/em> data for Palau during the 1997-1998 El Ni\u00f1o\/La Ni\u00f1a, which culminated in the horrific summer 1998 bleaching event. The general trend of rising water temperatures around Palau is worrying; by the mid-21st century temperatures will more often be close to the 30\u00baC level, and for longer periods.<\/span>[\/vc_column_text][vc_empty_space height=”25px”][vc_single_image image=”17939″ img_size=”full” qode_css_animation=””][vc_empty_space height=”25px”][vc_column_text el_class=”yellow-link-teal-bg”][\/vc_column_text][vc_column_text el_class=”yellow-link-teal-bg”]Impacts<\/strong>
\nGenerally, coral bleaching is associated with La Ni\u00f1a in Palau. During El Ni\u00f1o, when temperatures are low, deep mesophotic reefs become so cold that temperature becomes the limiting factor in the survival of deep reef corals (which do not do well in temperatures below 18-20\u00baC for long periods). A cursory look at the temperature by depth figure above shows that these cold conditions occur in the 57 to 90 m depth range.<\/span><\/p>\n

On a purely physical level, it is new environmental territory for Palau\u2019s reef corals as temperatures approach 30\u00baC more often and for longer periods . The abilities of stony corals and their symbionts to adapt to rising temperatures is uncertain, but qualitative evidence supports some ability to adapt to higher temperature conditions.<\/span>[\/vc_column_text][\/vc_column][\/vc_row][vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern” el_id=”img-gallery” el_class=”h-gallery”][vc_column][vc_gallery type=”image_grid” images=”17971,17972,17973″ img_size=”full” column_number=”3″ grayscale=”no” images_space=”gallery_without_space”][\/vc_column][\/vc_row][vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”grid” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern” css=”.vc_custom_1494900031563{padding-top: 75px !important;padding-bottom: 75px !important;}”][vc_column][vc_column_text el_class=”yellow-link-teal-bg”]<\/p>\n

Mean Sea Level<\/span><\/h3>\n

Tides in Palau are measured against the Palau datum, in either millimeters or inches\/feet. The former is preferred for any serious discussion of tides and sea levels, while the latter is often used in tide prediction tables.[\/vc_column_text][vc_column_text el_class=”yellow-link-teal-bg”]Short Term Sea Level Variation tied to ENSO<\/strong>
\nPalau has a semi-diurnal tide, two highs and two lows on a quasi-daily timing. The differences between high and low can be on the order of 2 meters over a single day on spring tides, or less than 1 m during neap tide periods. During El Ni\u00f1o events, mean tide is lower than usual, eg. 1998, and during La Ni\u00f1a events, mean tide is higher than usual, eg. 1988\/89.<\/p>\n

There is incredible short-term variability in Palau\u2019s mean sea level that overwhelms and disguises the long term upward trend. This variation in mean sea level (MSL) is driven by ENSO and local oceanographic conditions, rather than conditions controlling global rates of sea level rise.[\/vc_column_text][vc_empty_space height=”25px”][vc_single_image image=”17975″ img_size=”full” qode_css_animation=””][vc_empty_space height=”25px”][vc_column_text]The changes in mean sea level over months to years are often confusing as multiple things can occur at once, some working together, some working in opposition to each other. As the figure above shows, the day to day MSL varies up and down by about 300 mm over periods of weeks to months. An observer may see a dramatic rise or decrease in sea level (other than the daily tides) and think they are seeing the results of global sea level rise, when in fact it is simply variation caused by ENSO, or El Ni\u00f1o\/La Ni\u00f1a variation. Scientists can be fooled also if they limit their perspective to a small time period without looking at the big picture.[\/vc_column_text][vc_column_text]An extreme example of this variation is the time period at the end of 2015 and early 2016, indicated above by the red arrow. This period represents the shift between a strong El Ni\u00f1o and La Ni\u00f1a which was documented by Sch\u00f6nau et al. 2019<\/a>.[\/vc_column_text][vc_column_text]This is also seen in the graphs below, mean sea level (upper) and sea water temperature (lower). MSL dropped slowly and gradually by 600 mm (60 cm) between mid-2013 and the end of February 2016 as El Ni\u00f1o developed, a decrease of about 0.66 mm per day over 960 days. That\u2019s a very small number, less than 1 mm per day. What happened next was almost oceanographically unbelievable! The ENSO state rapidly changed from a strong El Ni\u00f1o to a La Ni\u00f1a. In early March 2016, MSL started rising in Palau, rocketing up the 600 mm in only ~ 70 days, reaching a rate of nearly 8 mm PER DAY for much of the time (upper graph). With mean sea level being interrelated with temperature, the water temperature climbed from some of the lowest shallow water temperatures ever seen in Palau to ~ 30\u00baC (lower graph) over this very short time period. This 30\u00baC temperature on Palau\u2019s reefs is associated with coral bleaching. Fortunately the La Ni\u00f1a was short lived, and the ENSO state returned to neutral quickly, resulting in more typical temperatures and mean sea level conditions.[\/vc_column_text][vc_empty_space height=”25px”][vc_single_image image=”17941″ img_size=”full” qode_css_animation=””][vc_empty_space height=”25px”][vc_column_text]Long Term Sea Level<\/strong>
\nGlobally sea levels are rising at about 3 mm per year, the result of melting of ice on land and thermal expansion of the water column with rising temperatures. If the last 60 years are considered, based on Palau\u2019s tide gauge data from Malakal, Palau fits right into this upward trend of 3 mm per year (see long term sea level graph above, red line).<\/p>\n

Another way to look at mean sea level rise in Palau is to look at the trend of the highest high tides, and the lowest low tides- BOTH show an upward trend. The gold line shows an upward trend for the lowest sea level recorded in one year, and the green line shows an upward trend for the highest sea level recorded in one year, since 1971.[\/vc_column_text][vc_empty_space height=”25px”][vc_row_inner row_type=”row” type=”full_width” text_align=”left” css_animation=””][vc_column_inner width=”1\/2″][vc_single_image image=”17942″ img_size=”full” qode_css_animation=””][\/vc_column_inner][vc_column_inner width=”1\/2″][vc_single_image image=”17943″ img_size=”full” qode_css_animation=””][\/vc_column_inner][\/vc_row_inner][vc_empty_space height=”25px”][vc_column_text]Impacts<\/strong>
\nProlonged low sea levels can affect reefs. In Palau from mid-2010 to mid-2013 corals grew up to their limits during the high MSL, and in early 2016 extremely low MSL caused prolonged exposure to air on low tides of these same corals. Many of these corals died, as documented by Colin and Schramek 2020 below.<\/p>\n

Higher than usual sea levels can lead to coastal erosion and flooding of low lying areas, taro patches and buildings along the coast. Salt water inundation into taro patches and homes along the coast usually occurs during La Ni\u00f1a events. During neutral or El Ni\u00f1o events, with normal to lower than usual sea levels, these areas are not flooded. An understanding of the variation of mean sea level during ENSO events is particularly important for building homes and structures near the coast, especially if building during an El Ni\u00f1o phase. Imagine land-filling and building according to the low mean sea level during an El Ni\u00f1o phase, only to be inundated during a neutral or La Ni\u00f1a event when mean sea levels are higher.[\/vc_column_text][vc_empty_space height=”25px”][vc_video link=”https:\/\/www.youtube.com\/watch?v=_5wUKd8WHGE&list=PLJCjKR2LY1a-54GNIbQpfY7Qbr2RsMaxE&index=”][vc_column_text][\/vc_column_text][\/vc_column][\/vc_row][vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”grid” angled_section=”no” text_align=”center” background_image_as_pattern=”without_pattern” background_color=”#39a694″ css=”.vc_custom_1614032748359{padding-top: 100px !important;padding-bottom: 100px !important;}” z_index=””][vc_column][vc_column_text el_class=”yellow-link-teal-bg”]<\/p>\n

This climate change summary for Palau is supported by Canada Fund for Local Initiatives.<\/span><\/h3>\n

[\/vc_column_text][vc_empty_space height=”25px”][vc_single_image image=”17961″ img_size=”full” alignment=”center” qode_css_animation=””][\/vc_column][\/vc_row][vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern”][vc_column][vc_single_image image=”17958″ img_size=”full” alignment=”center” qode_css_animation=””][\/vc_column][\/vc_row]<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

[vc_row css_animation=”” row_type=”row” use_row_as_full_screen_section=”no” type=”grid” angled_section=”no” text_align=”left” background_image_as_pattern=”without_pattern” css=”.vc_custom_1494900031563{padding-top: 75px !important;padding-bottom: 75px !important;}”][vc_column][vc_single_image image=”15753″ img_size=”full” qode_css_animation=”” css=”.vc_custom_1491176500169{margin-bottom: 25px !important;}”][vc_column_text] Climate change in Palau [\/vc_column_text][vc_column_text]Climate change has many complex layers, including the multiple factors that can affect weather patterns and the subsequent ecological impacts. Through this…<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":17588,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"full_width.php","meta":{"footnotes":""},"_links":{"self":[{"href":"https:\/\/coralreefpalau.org\/wp-json\/wp\/v2\/pages\/17925"}],"collection":[{"href":"https:\/\/coralreefpalau.org\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/coralreefpalau.org\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/coralreefpalau.org\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/coralreefpalau.org\/wp-json\/wp\/v2\/comments?post=17925"}],"version-history":[{"count":0,"href":"https:\/\/coralreefpalau.org\/wp-json\/wp\/v2\/pages\/17925\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/coralreefpalau.org\/wp-json\/wp\/v2\/pages\/17588"}],"wp:attachment":[{"href":"https:\/\/coralreefpalau.org\/wp-json\/wp\/v2\/media?parent=17925"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}