Published: 27 January 2015

Sea-level rise from 1990 to present higher than previously thought

The acceleration in global sea level from the 20th century to the last two decades has been significantly larger than scientists previously thought, according to a new study.

Building sea-walls, Tarawa, Kiribati: some low-lying islands are already experiencing the impact of rising sea levels.

Credit: Lauren Day/World Bank/flickr under CC BY-NC-ND 2.0

The study, co-authored by Carling Hay, a post-doctoral fellow with Harvard University, and Eric Morrow, a recent PhD graduate, shows previous estimates of global sea-level rise for the period 1900–1990 had been over-estimated by as much as 30 per cent. The report, however, confirms previous estimates of sea-level change since 1990, suggesting that the rate of sea-level change is increasing more quickly than previously believed.

The new work is described in a paper published in Nature.

‘What this paper shows is that sea-level acceleration over the past century has been greater than had been estimated by others,’ Morrow said. ‘It's a larger problem than we initially thought.’

‘Scientists now believe that most of the world's ice sheets and mountain glaciers are melting in response to rising temperatures.’ Hay added. ‘Melting ice sheets cause global mean sea level to rise. Understanding this contribution is critical in a warming world.’

Previous estimates had placed sea-level rise at 1.5–1.8 millimetres annually over the 20th century. Hay and Morrow, however, suggest that from 1901 until 1990, the figure was closer to 1.2 millimetres per year. But scientists agree that global sea level has risen by about 3 millimetres annually since that time, so the new study points to a larger acceleration in global sea level.

‘Another concern with this is that many efforts to project sea-level change into the future use estimates of sea level over the time period from 1900 to 1990,’ Morrow said. ‘If we've been over-estimating the sea-level change during that period, it means that these models are not calibrated appropriately, and that calls into question the accuracy of projections out to the end of the 21st century.’

To obtain their improved estimate of 20th century global sea level, Hay and Morrow approached the challenge of estimating sea-level rise from a completely new perspective.

Typically, Hay said, estimates of sea-level rise are created by dividing the world's oceans into sub-regions, and gathering records from tide gauges – essentially yard-sticks used to measure ocean tides – from each area. Using records that contain the most complete data, researchers average them to create estimates of sea level for each region, then average those rates to create a global estimate.

‘But these simple averages aren't representative of a true global mean value’ Hay explained. ‘Tide gauges are located along coasts, therefore large areas of the ocean aren't being included in these estimates. And the records that do exist commonly have large gaps.

‘Part of the problem is related to the sparsity of these records, even along the coastlines,’ Morrow said. ‘It wasn't until the 1950s that there began to be more global coverage of these observations, and earlier estimates of global mean sea-level change across the 20th century were biased by that sparsity.

‘We know the sea level is changing for a variety of reasons,’ Hay said. ‘There are ongoing effects due to the last ice age, heating and expansion of the ocean due to global warming, changes in ocean circulation, and present-day melting of land-ice, all of which result in unique patterns of sea-level change. These processes combine to produce the observed global mean sea-level rise.’

The new estimates developed by Hay and Morrow grew out of a separate project aimed at modelling the physics that underpin sea-level ‘fingerprints’.

To their surprise, Hay said, it quickly became clear that previous estimates of sea-level rise over most of the 20th century were too high.

‘We expected that we would estimate the individual contributions, and that their sum would get us back to the 1.5–1.8 mm per year that other people had predicted,’ Hay said.

‘But the math doesn't work out that way. Unfortunately, our new lower rate of sea-level rise prior to 1990 means that the sea-level acceleration that resulted in higher rates over the last 20 years is really much larger than anyone thought.’

Source: EurekAlert!

Published: 27 January 2015

Can the property development industry deliver climate-ready cities?

Eddo Coiacetto

Developers often cop criticism for being environmental vandals who’d do anything in the name of profit. But the industry is complex, ranging from one-off ‘mum and dad’ investors to global corporations. One thing they all have in common is that what they produce – residential and commercial developments – will need to perform in future environments that may call into question how or why the structures were built in the first place.

Gold Coast skyline, 2012: Coastal development in south-east Queensland may be impacted by more powerful storm surges and sea-level rise.

Credit: Mike R under CC BY-SA 2.0

There is no ‘typical’ property developer. Private property development is a complex, high-risk industry in which the developer is the entity, person or institution that manages the risks of development.

Unlike builders, developers do not have to be qualified, accredited or registered. While some may come from land-related professions and trades, others may be from unrelated fields, such as mining. Firms can be created specifically for a development project, then dissolve on project completion.

Can an individual developer deliver climate-ready developments? To an extent, some already do. The question though, is whether the entire collective of developers responsible for building cities – the development industry – can do it.

The question is important because developers play a key role in shaping cities.¹ Developments contribute to climate change because they impact on energy consumption and greenhouse emissions. New buildings and houses also affect the degree of exposure of users and residents to heatwaves, flooding and other extreme weather events. The extent to which they do depends on factors like:

location
site features
building features, and
private governance arrangements, such as covenants, easements and body corporate rules that developers put it place for users.

Regulation seeks to influence the above characteristics. But land use planning has had little traditionally to say about private governance arrangements. And building standards are relatively unproblematic and acceptable to developers: there is even a significant degree of industry self-regulation via green rating schemes, for example.

Importantly, controlling the location of developments, and to a degree their design, is politically charged, since it profoundly impacts property values and development feasibility.

At this point, it’s worth defining what a ‘climate-ready’ development industry would look like. It would be one that:

has the capacity to, and which can change to, deliver – in both the short and longer-term – products that reduce or minimise users’ exposure to climate hazards, and products that contribute to reducing energy use and GHGs; and
is at the same time resilient to, and has the capacity to deal with, climate change consequences, both direct and indirect.²

Developers’ exposure to the risks of climate change is limited because their commitment to a project is short – from several months to, at most, a couple of decades – compared to the lifetime of that development and the timeframes of predicted climate change hazards, such as sea-level rise.

Further, developers differ in their capacity and willingness to respond to the risks of climate change. They include builders, solicitors, ‘mum and dad’ developers, large diversified global corporations, mining companies, financial institutions and superannuation companies. They may be individuals or corporations, and may also be one-time operators, occasional developers, or professionals. Some developer ‘entities’ merely manage a development project for a fee while passing the risk of development on to equity investors, who may be ordinary people trying to save for their retirement.

Each entity has a different way of operating and some have more power than others to shape their operating environment. That environment is made up of diverse opportunities and risks – such as market risks, site risks, funding risk and planning risk. Different developers respond to the same stimuli (risk or opportunity) in different, even opposite, ways to other developers.

The problem therefore is that there can be no generic industry-wide response to climate change or to a climate -related regulation/policy. In other words, a given policy will not work with all developers.

Take land-use zoning to control the location of development, for example. Some developers only seek out land that is zoned for what they want to use the land for. However, other developers, perhaps with more time or power on their side, search only for land that is not zoned and then seek to rezone it because landowners want too much for zoned land.

As mentioned, the climate risks are not the same for all developers. A developer specialising in marina developments in North Queensland may be exposed to sea-level rise, storm surge and cyclonic activity; whereas one specialising in retirement units in central Queensland may be exposed to bushfires, drought, heat stress and inland flooding.

This discussion has so far focused only on the development industry. But climate-ready development necessitates a whole-of-sector approach, including landowners, financiers, builders and suppliers, engineers, consultants, and designers.

The role of finance is central and critical because it is this capital that is placed at risk in a development.

Policy makers can support the development industry’s adaptation to climate change by providing timely, accessible information.³

Many government departments are the custodians (and originators) of substantial data banks, yet access is often difficult, time-consuming and expensive. Strategies to improve transparency and communication of government data – such as long-term forecasts of storm surge levels – would go a long way to improving development appraisals. The easier the access to information, the more informed the eventual decision: for example, developers might avoid locations and sites at serious risk from climate change impacts.

So, while the outlook for the development industry (and its products) may sound grim, we cannot afford be pessimistic, because climate change presents an unprecedented threat. The solution thus requires an unprecedented level of consistent and concerted action by all players in the property and financial sectors, including all levels of government.

Associate Professor Eddo Coiacetto from Griffith School of the Environment, Griffith University, is interested in improving the effectiveness planning practice by basing it on a sounder understanding of the realities of urban development. Eddo is one of 31 experts who’ve contributed to the edited collection, Responding to Climate Change, published by CSIRO Publishing.

¹ Squires G & Heurkens E (2015) International Approaches to Real Estate Development. Abingdon: Routledge.
² Coiacetto E (forthcoming) Climate change governance in private real estate development: essential concepts about development for feasible research, regulation and governance. In JR Knieling (Ed.) Climate Change Governance: Theory, Concepts and Praxis in Cities and Regions. Wiley.
³ Coiacetto E, Shearer H, Dodson J, Taygfeld P & Banhalmi-Zakar Z (2014 ) One man's meat is another man's poison: why 'who' the developer is matters in climate change adaptation in the development industry. In P Burton (Ed.) Responding to Climate Change: Lessons from an Australian Hotspot. CSIRO Publishing.

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