Ten-year climate model unveiled

Scientists say they have developed a model to predict how ocean currents, as well as human activities, will affect temperatures over the next decade.
By including short-term natural events, such as El Nino, a UK team says it is able to offer 10-year projections.

Models have previously focused on how the globe will warm over a century.

Writing in Science, Met Office researchers project that at least half of the years between 2009 and 2014 are likely to exceed existing records.

However, the Hadley Centre researchers said that the influence of natural climatic variations were likely to dampen the effects of emissions from human activities between now and 2009.

But over the decade as a whole, they project the global average temperature in 2014 to be 0.3C warmer than 2004.

Currently, 1998 is the warmest year on record, when the global mean surface temperature was 14.54C (58.17F).

Doug Smith, a climate scientist at the Hadley Centre, explained how the new model differed from existing ones.

"On a 10-year timescale, both natural internal variability and the global warming signal (human induced climate change) are important; whereas looking out to 2100, only the global warming signal will dominate."

The latest assessment from the Intergovernmental Panel on Climate Change (IPCC), said that human activity was "very likely" causing the world to warm, and predicted the global average temperature were probably going to increase by 1.8-4.0C (3.2-7.2F) by the end of the century.

"It is the same model as used in the latest IPCC report's predictions for the coming century, but the difference is that it starts from the real observed status of the ocean and the atmosphere," Dr Smith, the paper's lead author, explained.

"Greenhouse gases and aerosols are also included, but it is really trying to predict any [natural] variability on top of that.

"We start with the present state of the ocean, and we try to predict how it is going to evolve," he told BBC News.

Better understanding

The model, called the Decadal Climate Prediction System (DePreSys), is based on a well established climate model already used by Hadley Centre scientists.

But in order to offer a projection for the coming decade rather than a century ahead, it also assesses the current state of the oceans and atmosphere.

This allows the researchers to predict how natural shifts, such as the El Nino phenomenon in the eastern Pacific and the North Atlantic Oscillation, will affect the global climate system.

They hope this data, when combined with projections of greenhouse gas and aerosol emissions from fossil fuels and volcanic eruptions, will present one of the most detailed outlooks to date.

"One reason why the 10-year projection has not been done before is because the ocean has traditionally had very poor observational coverage," Dr Smith said.

"They been very sparse and a little bit "noisy" so they have been difficult to interpret what the real temperatures were over large parts of the ocean."

However, recent improvements in data collection from satellites and in-situ instruments have allowed climatologists to improve their understanding of how ocean dynamics influence the climate system.

He added that decadal outlooks would provide businesses and politicians with meaningful information.

"Nearly all businesses have to make decisions on that sort of timescale; they plan for the next five to ten years.

"The climate has already changed, and it is continuing to change; people need the best information available to help them adapt to these changes."
-----------------
link