Green Tau: issue 30

The challenge of rising sea levels for Pacific islands.

20th January 2022

Last week the Green Tau focused on Richmond and the likely effects of the increased risk of flooding arising from climate change. This week the focus will be on Tarawa, one of the 33 atolls that makes up the Pacific nation of Kiribati.  

Tarawa is one of the largest of Kiribati atolls and is home to one 60,000  people, about 53% of the total population. Seen from above, Tarawa is a long thin strip of land that curves to form two sides of a triangle, in the middle of which is a lagoon. (Atolls are islands created by volcanic action. The former crater forms a dip in the middle). The third side of the triangle is below sea level and is home to a coral reef. It has a very long coast line in proportion to its land area. The land is flat and low lying, rising to about 2-3m above sea level.  Beaches on the lagoon side tend to be wider and shallower than this on the ocean side.

Scientific research suggests that the rise in average sea levels for Tarawa, by 2100,  will be between 0.5  (if the global temperature increase is kept below 1.5C) to 1.2m (if the increase in the worst case is 5-6C). Present projections suggest we are on track for a 2.7C temperature rise – and a projected sea level rise for Tarawa of 0.6m. High tide is typically 1.2m above the mean sea level, but is subject to variation. For example tide levels rise during periods when the El Niño weather system is dominant because the high pressure lifts sea levels. Because of its shape, with along coast lines and narrow low lying land mass, Tarawa – like many similar atolls and islands – is very vulnerable to rising seas levels. The people of Tarawa can see that before the end of this century they may no longer have an island on which to live! 

Sea levels also rise markedly when drive by cyclones. The Republic of Kiribati used not to be affected by tropical cyclones but with increasing global temperatures and changing weather patterns, this is no longer so. Not only do cyclones produce flooding with high waves, but the strong winds are particularly destructive to low lying lands such as on Tarawa with the winds breaking sea defences, ripping up vegetation and blowing away soil. (Soil depths are already shallow because these volcanic atolls are relatively youthful in geological terms). 

Tarawa is located on the Equator and it has a tropical rainforest climate. It rains on average every other day, with a high of rainfall of about 300mm a month in January and a minimum of 100mm in September. This ensures that the  water table is regularly topped up.  However the land above sea level at Tarawa is narrow, with saline after on both sides. Rising sea levels leads to the contamination of freshwater supplies with salt. This reduces water for drinking etc as well as damaging agricultural crops and plant life generally. 

Rising global temperature affect not just the air but also ocean temperatures. Since preindustrial times, global sea surface temperatures have risen by 0.7C. The rate of increase has risen in recent decades and particularly so in the last 6 years. Temperatures rises are not uniform and have been more marked in the southern Pacific waters. The IPCC predicts sea temperatures may rise by 1.2 to 3.2C by 2100 (depending on our ability to reduce carbon emissions). Rising sea temperatures affect marine life generally and reefs in particular. Temperature rises in the region of 1C can cause the bleaching of coral reefs. This draining of colour shows that the coral is stressed, and is likely to die.  Associated with heat rises accentuated by El Niño, Tarawa has had repeated incidences of coral bleaching. When coral reefs die and break down, they no longer protect local shores from erosion nor protect lagoons from destructive waves that destroy the particular ecology of those calmer waters. The loss of coral reefs also leads to losses  of  marine biodiversity.

Tarawa and the rest of the atolls in the Republic of Kiribati are not alone in facing these devastating effects of climate change. In 1990 they and other similarly vulnerable countries formed the Alliance of Small Island States to give themselves collectively a more voluble voice in discussion and proposals around the climate crisis. The AOSIS was a particularly strong presence at the Paris Climate Conference in 2015. Their voice was also heard at the Glasgow COP last year although because of covid fewer delegates were able to attend. One of those unable to travel was the former President of Kiribati, Anote Tong. Speaking from home, he told ITV News that beyond 2030 “our very existence might be in jeopardy”. 

In 2012 Tong bought a 2700 hectare estate on the island of Vanue Levu in Fiji as a refuge for the citizens of Kiribati, plus a further 2000 hectares in 2014. Between 2003 and 2015 the Kiribati Adaptation Plan was executed using money raised by the United Nations from wealthy donors such as Australia This included projects such as planting mangrove palms to limit coastal erosion, strengthening sea wall defences, and installing rainwater butts to help safeguard fresh water supplies. 

In 2020 the new President of Kiribati, Taneti Maamau, announced plans, in conjunction with China, to artificially build up parts of Tarawa, to raise them above projected sea level rises.

In the mean time other adaptations projects are on going to improve the islanders’ living standards and build up their resilience in the face of flooding. These include encouraging islanders to develop traditional food gardens to protect against sudden food shortages (much of Kiribati’s food is imported), developing fish management schemes to prevent over fishing, and increasing provision shade to protect people from adverse temperatures. Consideration is now being given to using the land bought in Fiji to provide food for Kiribati. It seems that due to poverty, the people of Kiribati are not well equipped to cope with the extra demands and risks of the climate crisis. Equally important are these projects designed to improve their living standards, health and well being.

Counting On …

8th November 2021

Today’s agenda at COP26 features adaptation, loss and damage. The extreme weather conditions we have seen in recent years – droughts and wildfires, floods and heat waves, storms and cold snaps – are here to stay as a direct consequence of the 1C warming that has already taken place. Current efforts at COP26 will hopefully constrain further rises in temperature to no more than 1.5C.

Across the globe, communities are and will have to adapt to the changes that are happening in weather patterns. In the UK we need plan how we cope with more frequent and deeper floods, spasmodic heat waves and irregular growing seasons. In the Pacific region where there are many low lying islands and around river deltas such as in Bangladesh, there is the need to plan for rising sea levels  which not only submerged land where people live but also salinates water used for drinking and farming. Many sub Saharan regions are faced with prolonged heat waves that make daily life and farming near impossible. Whilst other regions will feel the affects of drought as rivers that are normally fed during the summer by the slow melt of glaciers, dry up as the glaciers disappear altogether. 

Time and again, the solution lies with trees, whether that is trees that interrupt, and delay the speed with which falling rain becomes flood water, trees that stabilise coasts vulnerable to erosion, tree shade that reduces experienced daytime temperatures, or trees that provide shade for crops and whose roots retain moisture in the soil. 

 “Locally, trees provide most of their cooling effect by shading. How warm we feel actually depends less on local air temperature, and more on how much electromagnetic radiation we emit to, and absorb from, our surroundings. A tree’s canopy acts like a parasol, blocking out up to 90% of the sun’s radiation, and increasing the amount of heat that we lose to our surroundings by cooling the ground beneath us.All up, the shade provided by trees can reduce our physiologically equivalent temperature (that is, how warm we feel our surroundings to be) by between seven and 15°C, depending on our latitude. So it’s no surprise that, in the height of summer, people throng to the delicious coolness of the shade provided by London parks, Parisian boulevards, and Mediterranean plazas.

Trees can also cool down buildings – especially when planted to the east or west – as their shade prevents solar radiation from penetrating windows, or heating up external walls. Experimental investigations and modelling studies in the USA have shown that shade from trees can reduce the air conditioning costs of detached houses by 20% to 30%.”

https://theconversation.com/can-trees-really-cool-our-cities-down-44099

Eco tip: how to keep cool in hot weather

  1. Drink lots of fluids.
  2. Dress in loose light coloured and light weight clothes. Go bare foot. Wear a sun hat.
  3. Close curtains and open windows to keep the sun out and air moving through the room. Open windows on different sides of the house and different floors to encourage air to move through the house. 
  4. Turn off unused electrical appliances, even those on sleep may be emitting extra heat into the room.
  5. Hang wet towels over or near an open window, or place a bowl of water or ice by the window. Air moving through or across will absorb the moisture and cool the room. 
  6. Shade the outside of the window to prevent the glass from heating up and radiating heat into the room. You could use a sheet or towel as an ad hoc shade. Or place a gazebo or sun parasol to shade the window. Longer term consider fixing an awning to shade south facing windows. Or erect a pergola outside and allow climbing plants to shade the window.
  7. Sit with your feet in a bowl of cold water. Keep damp flannels in the fridge for a cool wipe.
  8. Freeze a plastic bottle of water (don’t completely fill the bottle as frozen water expands)  and use it as a cold ‘hot’ water bottle. To avoid ice burns wrap in a towel before placing it on your skin. Alternatively place in your bed at night.
  9. Fill a sock with rice, secure the end and place in the freezer. Use as a cold pad or as cold ‘hot’ water bottle in your bed. 
  10. Get up early and start your day while it is still cool. Catch up on sleep later with an siesta when its hot.
  11. Have you a tip to share?

The Green Tau Issue 7 11th July 2021 Are extreme weather events here to stay?

Extreme weather conditions – floods, droughts, wild fires, heat waves, hurricanes, blizzards -are now more frequent and more severe. 

http://www.max pixel.net Orange Heat Danger Blaze Smoke Blazing Wildfire

The energy that creates weather comes from the sun. The sun’s heat warms land, sea and air where differences in temperature create ocean currents and air currents – winds. When air moves across the seas it picks up moisture which ultimately becomes rain. The hotter the air the more water is taken up and held in the air. Again heat becomes a determinate of rain fall patterns – both quantity and intensity of rain fall (or snow etc) – eg monsoons in India after their hot season.

Air, land and sea are all heated directly by the sun. They are also heated indirectly by radiant heat from the earth. During the course of a day, in the absence of cloud cover, air temperatures will rise further as the heat from the sun is supplemented by heat radiating back from the earth. If the lack of cloud cover persists overnight, the radiant heat is lost into the upper atmospheres and the air temperatures drop. If however it is a cloudy night, the cloud will act like insulation keeping in the warmer temperatures. 

Given that the sun has always been there, why are temperatures now increasing at a rate that are creating extreme weather events? 

The Earth’s atmosphere is a mix of oxygen, nitrogen, carbon dioxide plus smaller quantities  of other gases. Of these carbon dioxide is particularly good at absorbing heat and thus preventing extremely low temperatures when the earth’s surface is not receiving direct sunlight. Since the beginning of the Industrial Age we humans have been burning increasingly large amounts of fossil fuels such as coal, oil and gas. As these burn they release carbon dioxide. As levels of carbon dioxide in the atmosphere have increased so the insulating effect has also increased, and with it global temperatures – and with that an increase in extreme weather events.

Global annual average temperature (as measured over both land and oceans) has increased by more than 1.5°F since 1880 (through 2012). Red bars show temperatures above the long-term average, and blue bars indicate temperatures below the long-term average. The black line shows atmospheric carbon dioxide (CO2) concentration in parts per million (ppm), indicating a clear long-term global warming trend.

(Figure source: 2014 National Climate Assessment, updated from Karl et al. 2009)

The UN reported that across the world, between 2000-2019, there were 7,348 major disasters, claiming 1.23 million lives, affecting 4.2 billion people and causing £2.3tn in economic losses. Whilst in the UK flooding affected the Midlands and northern England in 2019 after the wettest November on record, and again in 2020 affecting Wales and southern England. The freezing temperatures of the ‘Beast from the East’ in February 2018 were followed by a heat wave from May to July with wild fires in areas near Manchester. 

Since 1950 carbon levels in the atmosphere have risen from 311 parts per million to the current level of 414 ppm whilst average global temperatures have risen by just under 1C. The Paris Agreement set out to keep global temperature rises below 2C max and ideally below 1.5C, requiring  global carbon dioxide emissions must be reduced to net zero by 2050. As this is not going to reduce temperatures below where they are now, extreme weather events are something we have to accept and adapt to. 

Adapting to our new climate is one issue that will be addressed at the COP26 climate conference. It is also something that we can work at too. Insulating homes not only keeps them warmer in colder months, it also keeps them cooler in hot months. Win win plus reduces energy needs for cooling / heating. Planting trees creates shade and because of the way they ‘breathe’ reduce temperatures further by absorbing heat. In Rotterdam a 10% increase in tree cover produced a 1.3C reduction in temperatures ( Klok et al. 2012). Trees also lock away carbon dioxide and slow the rate at which rain water fills soils and drains so reducing the risk of flooding. A further win win solution.  

Urban areas heat up faster than others because they have large areas of concrete and tarmac which readily radiate the sun’s heat back into the atmosphere. Reducing these or replacing them with grass or vegetative cover again reduces high summer temperatures. Creating cool areas around buildings with verandas, planting in trellises and planting in general will cool the air coming into the buildings as well as providing areas of shelter from the heat.