Getting it Wright on sea level rise

Sea level rise of up to 40cm around New Zealand by the middle of this century is already locked in and will cause significant problems for coastal communities and infrastructure, according to a new report just released by Dr Jan Wright, the Parliamentary Commissioner for the Environment. The report — Changing Climate and Rising Seas: Understanding the Science [pdf] — provides an overview of why sea levels are currently rising and why they are expected to continue rising over the rest of this century and beyond. A follow-up report due next year will “show in some detail which areas of the coastline around the country are most vulnerable to sea level rise and assess the risk to infrastructure in those areas”.

Introducing the report, Dr Wright said that the scientific evidence is now irrefutable. “The climate is changing and causing the sea to rise”.

“A rise of 30 cm may not sound much, but its impact will be very costly for many landowners. Damaging coastal floods will become increasingly frequent. The insurance industry is becoming aware of, and responding to, the increased flooding risk. Some councils and communities have already started to face hard questions.”

Commenting on the report for the Science Media Centre, Associate Professor Nancy Bertler of the Joint Antarctic Research Institute, Victoria University of Wellington/GNS Science, said:

The report provides an excellent summary on the current knowledge of past and future sea level rise including the main drivers and the regional patterns. Dr. Wright highlights the concern of the scientific community on the possibility of substantial and abrupt future contributions from the West Antarctic ice sheet.

Additional important considerations are that: worldwide over 200 million people live within one metre of sea level. The last time atmospheric carbon dioxide concentration was at 400 ppm (3-5 million years ago) the associated global temperatures caused the Greenland and West Antarctic ice sheets to catastrophically collapse – raising global sea level by around ten to twenty metres.

The rate at which sea level will rise has important implications on our ability to adapt. New research suggests that sea level could rise as quickly as 4 metres per 100 years (or 1 metre per 25 years). Assuming even a modest global sea level increase of 50 cm by 2100 (IPCC scenario RCP 4.5), the frequency of coastal inundation in New Zealand is predicted to increase by a multiplier of 1000 times.

Under such a scenario, an annual event becomes a daily event, a ‘100 year’ event occurs several times per year. As an approximation: every 0.1m rise triples the frequency of inundation events.

Dr Wright focusses on the near term implications for New Zealand, a sensible choice given the tendency to dismiss sea level rise as a problem for the distant future, but in my view she misses an opportunity to spell out the strong relationship between atmospheric CO2 levels and equilibrium sea level. The last time CO2 stood at 400 ppm, global sea level was about 20m higher than today. That’s where we’re heading, unless we can get greenhouse gas levels down, and it has very important implications for emissions policy. But I’m nit-picking…

Changing Climate and Rising Seas is a very readable introduction to the science of sea level rise, and gives a very clear picture of the state of current knowledge. It’s a welcome addition to what passes for national discourse on the inevitability of climate change and the necessity of adapting to what it brings. Next year’s report on regional impacts will be even more important.

Bangladesh: lessons in adaptation

A basket case, said Henry Kissinger of Bangladesh in 1974 after the civil war that liberated it from West Pakistan (the side he backed). Mark Hertsgaard in Hot (reviewed here) reports a rather different picture. I thought it worth dwelling longer on what he has to say about Bangladesh than was possible in the review because he shows the Bangladeshis as far from passive even in the face of what look like daunting odds, and because he underlines the case for assistance.


Bangladesh’s ambassador to the US, in conversation with Hertsgaard, firmly refutes the Kissinger perspective.

We are now feeding ourselves, 140 million people. We have cut our population growth rate in half. All Bangladeshi children are immunized against major childhood diseases. Our economy has grown an average 5.5 percent a year over the last seventeen years. We are not a basket case at all.

Hertsgaard acknowledges the advances, but recognises the threat they are under from climate change. The vulnerability of Bangladesh is well known. Two-thirds of the country stands less than sixteen feet above sea level. The three feet of sea level rise that Hertsgaard regards as unavoidable will displace an estimated 20 million Bangladeshis. Soil and water in coastal regions are already becoming too salty to deliver traditional rice yields. There’s plenty to suggest that Bangladesh appears doomed in the face of fifty more years of global warming. However, says Hertsgaard, spend some time inside the country and things look different.

He singles out the human factor. It counts for a lot in adapting to climate change. Bangladeshi biologist, Saleemul Huq, an influential advocate for the poor within the global climate change discussions, spoke to him of the resilience developed by people who have been dealing with floods and other disasters for centuries, “so they have greater capacity than rich people who are not used to facing catastrophe”. The months Huq spent researching among river communities of fishing families were an eye-opener for him, brought up in more favoured circumstances.

I got to know the poor as individuals, not as an abstraction. I saw they were extremely resilient and often ingenious at coping with the circumstances they faced.

Huq and others have subsequently developed an approach called Community-Based Adaptation in which experts on climate change impacts work together with poor communities in a dialogue of equals where local solutions which draw on the experience of local people can be devised.

Hertsgaard describes some of the adaptation measures he saw when visiting the Bangadeshi countryside. In one village a farmer had taken some simple steps to protect his family against the storm surges of cyclones. With NGO help he had elevated his mud and thatch house five feet above ground, on a mound of packed dirt with hard dirt steps leading up to the entrance. He explained to Hertsgaard that it had worked well and that during the last two cyclones they hadn’t had to go to the cyclone centre, which gets very crowded and short on food and water. Their own food, rice and fish, was kept dry during the floods in a basket made from tightly woven strands of bamboo, which floats.

In another village they relied on “floating gardens”. The villagers wove water hyacinth plants into a watertight mesh. The one Hertsgaard saw measured about fifteen feet long and ten feet wide and floated in one of the many ponds in the village. The mesh was covered with a few inches of topsoil, which was planted with vegetables. Since the structure floated it simply rose higher in flood inundation. The same village was also seeking to diversify its income sources by establishing, with NGO help, a tree nursery that grew mango and other fruit trees as well as medicinal herbs. Seedlings were sold in the local market.

These are very local and specific small measures, but the Bangladeshi government, in spite of its frequent dysfunctional bouts, has also been working on the wider picture for the past twenty years. With help from foreign donors it has invested $10 billion to bolster defences against floods, cyclones and drought. It has also pursued climate-focused agricultural research and is testing varieties of rice that could survive immersion in salt water for longer than two weeks. If successful that would help farmers cope with flash floods that mix sea and river water and will occur more frequently as sea levels rise. The government has developed an action plan to prepare for climate change on many fronts. But it will need money. Early estimates suggest that the first five years of work on the plan would cost about $5 billion. Some of this Bangladesh itself will pay for, but it can’t meet it all and it calls on the international community “to provide the resources needed to meet the additional costs of building climate resilience”.

Huq puts the obligation of the rich countries this way:

It is poor countries that are suffering the brunt of climate change, but it is the rich countries’ greenhouse gas emissions that caused this problem in the first place. If we follow the principle of “the polluter pays” they are obligated to pay damages. It is important to understand that this is not charity, like money given to poor countries for economic development. This is compensation.

US chief climate change negotiator Todd Stern told the Copenhagen climate summit that he “absolutely” rejected the suggestion that the US owes a “climate debt” to the rest of the world. Hertsgaard comments that as a lawyer himself Stern must surely know that in a court of law damages are damages, regardless of one’s intent.

I appreciated the attention Hertsgaard gave to the way Bangladesh is trying to face up to the challenges of climate change adaptation. The changes are real for them. They may be congruent with challenges they have long faced as part of their normal life, but they are mounting and threatening. Some of the adaptive measures he describes may turn out to have only been buying time as the sea continues its inexorable rise, but they are worthy of respect. They are also worthy of assistance.

The poor ask far less of life than we are accustomed to demand and the help they are seeking is not large by our standards. We would help them most, of course, by seriously taking in hand the task of drastically reducing greenhouse gas emissions, but while we continue to refuse this we at least owe them a measure of compensatory assistance.

On an island: coping with sea level rise

A recent Rowntree Foundation report on the vulnerability to the effects of climate change by mid-century of Britain’s coastal communities has attracted some media attention. It struck me as underlining the relevance of one of the chapters in the book Adapting to Climate Change which I recently reviewed on Hot Topic. The chapter, on adaptive governance for a changing coastline, noted a strategic shift in national coastal management policy in England away from investing in expensive ‘hard’ engineered defence towards designing a more naturally functioning coastline. This means that many coastal communities now face great unease and anxiety about their future, since the new policy preferences for retreat and realignment mean no future guarantees for protection.

[See end for comments by Gareth.]

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Dealing with sea level rise: retreat, defend, or attack?

As a handy follow-up to Bryan’s post yesterday about calls to plan for sea level rise of about two metres over the coming century, a new report, Facing up to rising sea levels [PDF], examines how two British coastal cities, Portsmouth and Hull, might cope. According to the Guardian coverage, Hull could become a “Venice-like waterworld” (which is a considerable challenge to my imagination) and Portsmouth a new Amalfi (ditto). Set aside the hyperbole, however, and the report — a joint effort by the Royal Institute of British Architects and the Institution of Civil Engineers — is an examination of how the cities could respond to sea level rise by building defences, managing a planned retreat, or by building out and over the sea as it rises. The results are a fascinating look at how ingenuity in the face of a severe challenge can create interesting environments — if not, perhaps, a new Venice in northeast England.

Wade in the water

Estimates of the sea level rise that will result from continued global warming continue to increase, with two recent papers adding more evidence that the IPCC AR4 projections were unrealistically low. The rise this century could be as high as 1.9 metres, and the long term response to a warming limited to 2ºC could be 6 – 9 metres the studies suggest. There are also signs that New Zealand planners are beginning to take the issue seriously, with Nelson and Wellington both considering the impacts of sea level rises of over a metre.

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