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Published: 1 September 2014

Missing heat may be hiding deep in the Atlantic


More than a dozen theories have now been proposed for the so-called global warming hiatus, ranging from air pollution to volcanoes to sunspots. A new study shows that the heat absent from the surface is plunging deep in the north and south Atlantic Ocean, and is part of a naturally occurring cycle.

Atlantic Ocean waves crash on the shore.
Atlantic Ocean waves crash on the shore.
Credit: Kim Seng CC BY-NC-ND 2.0

According to the University of Washington (UW) study, just published in Science, subsurface ocean warming explains why global average air temperatures have flatlined since 1999 despite greenhouse gases trapping more solar heat at the Earth’s surface.

‘Every week there’s a new explanation of the hiatus,’ said corresponding author Ka-Kit Tung, a UW professor of applied mathematics and adjunct faculty member in atmospheric sciences.

‘Many of the earlier papers had necessarily focused on symptoms at the surface of the Earth, where we see many different and related phenomena. We looked at observations in the ocean to try to find the underlying cause.’

The results show that a slow-moving current in the Atlantic, which carries heat between the two poles, sped up earlier this century to draw heat down to 1500 metres.

Tung and co-author, Xianyao Chen of the Ocean University of China, used recent observations of deep-sea temperatures from Argo floats, which sample the water to a depth of 2000 metres. The data show an increase in heat sinking around 1999, when the rapid warming of the 20th century stopped.

‘There are recurrent cycles that are salinity-driven that can store heat deep in the Atlantic and Southern oceans,’ Prof Tung said. ‘After 30 years of rapid warming in the warm phase, now it’s time for the cool phase.’

In an earlier study, the researchers proposed that rapid warming in the last two and a half decades of the 20th century was roughly half due to global warming and half to the natural Atlantic Ocean cycle that kept more heat near the surface. When observations show the ocean cycle flipped, in about 2000, the current began to draw heat deeper into the ocean, working to counteract human-driven warming.

The cycle starts when saltier, denser water at the surface northern part of the Atlantic, near Iceland, causes the water to sink. This changes the speed of the huge current in the Atlantic Ocean that circulates heat throughout the planet.

‘When it’s heavy water on top of light water, it just plunges very fast and takes heat with it,’ Tung said.

The oscillations have a natural switch. During the warm period, faster currents cause more tropical water to travel to the North Atlantic, warming both the surface and the deep water. At the surface this warming melts ice. This slowly makes the surface water there less dense and after a few decades puts the brakes on the circulation, setting off a 30-year cooling phase.

However, Prof Tung pointed out that now, ‘we are not talking about a normal situation because there are so many other things happening due to climate change’.

Source: University of Washington







Published: 4 July 2011

Assured sustainability reporting – navigating obligations

Nick Fleming

As the way in which organisations address environmental, social and governance (ESG) issues comes under increasing scrutiny, sustainability reporting is gathering importance and momentum. Yet reporting must be seen as a product of sustainable business practices, not the focus of it.

Emphasis on more robust sustainability reporting is helping to drive the wider assessment and reform of companies’ associated supply chains and logistics infrastructure.
Emphasis on more robust sustainability reporting is helping to drive the wider assessment and reform of companies’ associated supply chains and logistics infrastructure.
Credit: iStockphoto

While sustainability reporting is new territory for some organisations, many leading businesses have been engaged in reporting for over a decade. Indeed, sustainability reporting is typically one of the first vehicles for engagement with the topic and issues of sustainability, often at the encouragement of a few passionate staff.

However, the call for greater organisational accountability and transparency is growing. An increasing number of shareholder resolutions are placing pressure on company boards to ensure they are effectively identifying, disclosing and addressing ESG risks. Institutional investors are already using ESG data to differentiate firms and guide investment decisions.1

Powerful customers are also forcing their suppliers to become more transparent. The classic example is Walmart, which launched a supplier sustainability initiative in July 2009. Locally, Woolworths recently announced its own Sustainable Fish Sourcing Strategy.2

There is also an expectation for assurance. This reflects a stakeholder desire for reports to be relevant, reliable and free from bias, while the reporting organisation wishes to build a case for lower costs for finance and insurance. This all takes time and money; reporting can be a costly exercise and carries risks.

The banking sector provides an insight to the challenges posed by sustainability reporting. In Australia, banks have typically lead sustainability reporting and have performed well against international benchmarks such as the Dow Jones Sustainability Index. Yet this year, the big four banks have been publically criticised over their involvement with coal-fired power stations.3 People ask how an organisation that receives sustainability accolades can also finance environmental pollution. This questions the connectivity between sustainability reporting and governance.

Scrutiny is also being applied by the regulators. The Australian Competition and Consumer Commission has prosecuted cases against companies such as GM Holden and Prime Carbon for overstating their ‘green’ credentials. It’s clear that inaccurate communication on ESG matters presents serious risks to an organisation’s reputation – and that of the rating or assurance agency.

These issues have been behind recent reviews of reporting guidelines and benchmarking methods.4,5 The reviews found that ratings and reporting tend to be backward-looking measures of compliance with ‘good practice’, failing to enable a meaningful assessment of an organisation’s ability to create and sustain value, in the short and longer term.

What’s lacking is adequate interrogation and reporting of the strategic capabilities and the core competencies required to underpin business continuity and delivery of sustainable outcomes; that is, a truly sustainable enterprise.

However, the push for integrated financial and non-financial (sustainability) reporting may offer a silver lining – the trigger to focus conversations among executives and boards about the things that will drive genuine business continuity, profitability and sustainability. Without these conversations, there will neither be the understanding, focus nor commitment to cultivate truly sustainable enterprises.

The adage ‘What gets measured gets managed’ remains true; as does ‘It’s what you do, not what you say, that counts’. Reporting without subsequent actions to manage risks and create value is meaningless, and arguably harmful.

While there are growing market and stakeholder pressures for integrated reporting of financial and ESG matters, reporting should only be entered into with an eye on:

  1. material business risks

  2. core competencies for organisational continuity

  3. a core set of meaningful performance measures that offer real insight

  4. integrating reporting into governance

  5. commitment to real action in response to identified risks and opportunities.

Organisations that assume this approach take sustainability reporting beyond a ‘nice?to?have’ PR exercise to a ‘must?have’ business improvement tool. It’s a factor in the superior financial performance demonstrated by ethical and sustainable organisations. Getting it right is good for business – and good for communities.

Dr Nick Fleming is Chief Sustainability Officer Sinclair Knight Merz, leading the application of sustainability thinking in business operations and client services. Through his Sustainable Enterprise column, Nick provides insight to how businesses and organisations are effectively putting sustainability theory into practice.


1 Ernst & Young (2011). Shareholders press boards on social and environmental risks. tinyurl.com/social-environmental-risks
2 tinyurl.com/sustainable-fish
3 Greenpeace (2011). Pillars of pollution. www.greenpeace.org.au/climate/GI-profundo.php
4 Eccles RG, Cheng B, Saltzman D (Eds) (2010). The landscape of integrated reporting: reflections and next steps. Harvard Business School. tinyurl.com/integrated-reporting
5 SustainAbility (2011). Rate the raters: uncovering best practices. www.sustainability.com/library/rate-the-raters-phase-one




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