On current trends, in just over 10 years from now the amount of power spent running and connecting to the world's communications networks will equal the total 2010 global energy supply.
That's if current technology is used.
Fortunately, as Rod Tucker, emeritus professor of engineering at Melbourne University, pointed out in a seminar on green computing in Auckland earlier this month, it can be largely offset by steady improvements in the power consumption of computers, servers, routers and all the other bits of silicon and metal that move bits around.
Replacing equipment when the depreciation schedule demands it, rather than sweating extra months or years out of that server or PC, is better for the planet.
Green computing isn't high on the priority list for most New Zealand firms surveyed by technology research firm IDC, but saving cost is - and that could make them look green sooner rather than later.
Vernon Turner, IDC's Boston-based senior vice-president for research on sustainability, says the information and communications technology sector can play a significant role in reducing greenhouse gas emissions.
He says that will mean talking to policymakers - but since many governments around the world seem to be avoiding leadership on the issue, industry may have to step up.
Challenges to green IT include the fact business and operational requirements will take priority over environmental concerns, and it can be hard to find benchmarking data to show any progress - just look at the resistance to accepting data that shows that climate change even exists.
There is not enough renewable energy currently available to drive all of the initiatives people may want to do, and there aren't that many people around who can give good advice on what to do.
Turner says it's rare for organisations to have dedicated staff responsible for sustainability, but it is possible to argue such staff could pay for themselves in future savings.
There is a tendency in New Zealand to feel our total carbon production is too low to mean savings will make any significant difference to climate change, but Turner says there's no room for smugness, especially if our trading partners start demanding action.
New Zealand's record on carbon emissions doesn't look so flash either. While it only amounts to 9 tonnes per person, when you compound annual growth between 1990, the benchmark for the Kyoto Accord, and 2006, the last year with figures useful for comparison, the growth rate stood at 72 per cent.
That probably reflects population growth through migration and the dairy boom.
In contrast, Australia's compound growth rate was 51 per cent - its reliance on coal-fired power stations meant twice the volume of carbon was produced per person.
The United States also produces about 17 tonnes of carbon per person, but its compound growth rate was a mere 17 per cent.
The current IT infrastructure contains a massive carbon footprint, but shifting to something greener can't be done overnight.
It will require energy-efficient devices with lower power consumption and high performance, as well as energy-efficient networks.
Turner says waste management, recycling and re-manufacturing of infrastructure need to be measurable and accountable - it's not good enough just to ship scrap off to China or India.
IT can contribute to savings through smarter energy generation and distribution, smarter buildings and reduction in transportation.
Smart grids and smart meters can lower power use and allow the orderly integration of renewable sources such as wind and solar power into the grid.
Energy management systems, smarter building design and more teleworking can reduce the drain of our workplaces on the environment.
IT can also cut energy use in industry through things such as intelligent motor controllers and automation of industrial processes.
Turner says it's not pie-in-the-sky stuff. There are technologies with the potential to reduce emissions in energy, transport, buildings and industry that are mature enough now that given reasonable investment, they could be implemented in three years.
Broadband is especially important, as it has the potential to decentralise business and make physical daily travel much less necessary.
Turner says further investment in telecommunications and network services will enhance New Zealand's ability to improve to move up the sustainability index.
He estimated New Zealand could save more than 10 million tonnes of carbon by 2020 through IT, including 24 per cent from power savings, 22 per cent from smarter buildings, 10 per cent from industry and 44 per cent in the transport sector.
Turner says an area in which IT will make a big impact is the shift to cloud computing and the efficiencies that can be driven through virtualisation and consolidation.
Every watt saved in the data centre means four less watts that need to be generated at the power station, because of reductions in cooling, lighting, networks and other infrastucture.
Every server removed from the data centre through virtualisation saves 10 tonnes of carbon emissions through its lifecycle.
Data has an energy cost. It may be far more energy efficient to send data by airmail than over the internet, but the difference between flying someone from Australia to New Zealand for a business meeting has 200 times the greenhouse impact as conducting the meeting by videoconference.
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