'Best estimate' for impact of melting ice on sea level rise

Researchers have published their most advanced calculation for the likely impact of melting ice on global sea levels.

Researchers say they now have the most accurate estimate yet for the impact of the melting of ice sheets

The EU-funded team says the ice sheets and glaciers could add 36.8cm to the oceans by 2100.

Adding in other factors, sea levels could rise by up to 69cm, higher than previous predictions.

The researchers say there is a very small chance that the seas around Britain could rise by a metre.

The last Intergovernmental Panel on Climate Change (IPCC) report was highly detailed about many aspects of Earth's changing climate in the coming decades.

Advanced models

While it estimated that sea levels could rise by 18-59cm by 2100, the report was very unsure about the role played by the melting of ice sheets and mountain glaciers.

To fill the void, the EU-funded experts from 24 institutions in Europe and beyond tried to produce more accurate figures on the melting of Antarctica and Greenland and how this might swell the oceans.

Called Ice2sea, the group of scientists has made what it terms the "best estimate" yet of the impact of melting based on a mid-range level of carbon emissions that would increase global temperatures by 3.5C by the end of this century.

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"For that one scenario we have an ice sheet and glaciers contribution to sea level rise of between 3.5 and 36.8cm by 2100," said Prof David Vaughan from the British Antarctic Survey, who is the co-ordinator of the Ice2sea programme.

While the range is wide, the scientists say it is a relatively robust calculation and based on several advances in modelling since the last IPCC report.

"In order to be able to model the ice sheet properly, you need to be able to resolve things down to hundreds of metres," said Prof Tony Payne from the University of Bristol.

"That's quite a task when an ice sheet is a thousand kilometres or more in size; that's a very demanding computational task. What we found is that the Pine Island Glacier, the poster child of sea level rise in the Antarctic - that will continue through to the end of the century and very little else happens."

Despite the improvements, there are still many factors that are difficult to include in models. To get around this, the leading researchers were asked to estimate the worst-case scenarios.

They concluded there was a one-in-20 chance that the melting ice would drive up sea levels by more than 84cm, essentially saying there is a 95% chance it would not go above this figure.

While ice melt is a major contributor to the height of the seas, there are other important factors especially thermal expansion caused by the warming of the waters. This contributes about a third of the observed 3mm rise in sea levels every year.

Taken together with the ice melt estimate, the scientists say the overall, maximum impact on the seas by 2100 will be a rise of 69cm - just 10cm higher than the IPCC projection in 2007, termedAR4.

"What we are talking about is a reduction in uncertainty - we find we haven't changed the number enormously compared to AR4," said Prof Vaughan. "We've added maybe another 10cm but the level of certainty we have around that is actually higher than it was in the AR4."

The researchers also included projections for sea level rise in Europe that includes the effects of thermal expansion, ice melt and storm surges. In these scenarios, the British Isles could face an increase of slightly over a metre by 2100 - enough to overwhelm the Thames Barrier and see London flooded once every 10 years.

But the scientists stress that there is a 95% chance that these numbers will not be reached.

"The previous IPCC identified this gap in our knowledge. We've addressed that gap and what we've found is not scary," said Prof Payne.

"We're always talking about tens of centimetres, maybe a metre tops. None of the experiments are suggesting 2, 3, 4m and that's different to the literature that existed before Ice2sea."

However, the scientists stressed that sea level rise in line with their projections could still make some islands in the Pacific uninhabitable. And if global emissions of carbon dioxide are not curtailed then the actual level of the sea by 2100 could be significantly higher than the Ice2Sea estimates.

By Matt McGrathEnvironment correspondent, BBC News

Indian tigers facing extinction, because of DNA

Scientists say tigers in India could become extinct because of a lack of diversity in the DNA of the breed 

It's estimated there are now fewer than 2,000 tigers in the whole world, and experts think 60% of those are in India.

In the early 1900s there were an estimated 100,000 tigers in India alone.

Since then numbers have dwindled, mainly because they used to be hunted by British officials and Indian royalty.

Experts say trophy hunting reduced the animal's numbers from 40,000 in just 100 years.

Since then though, despite conservationists' efforts to change culture and protect the species, the numbers have continued to drop.

Loss of habitat

Prof Bruford of the Cardiff School of Biosciences has been leading the research, he said there are now several other factors that are causing the threat of extinction.

He explained that 'a loss of habitat... meaning lower population sizes, means their gene pool is no longer mixing across the subcontinent."

He said this means groups of tigers are living in very separate areas and because of human populations and changes to the landscape groups of tigers will no longer mix.

This he says causes the problem of 'inbreeding' because the tigers that are grouped together are now more likely to share the same genes.

Mr Bruford said: "This is important because tigers, like all other species, need genetic diversity to survive - especially under climate change - so what diversity remains needs to be managed properly so that the Indian tiger does not become inbred, and retains its capacity to adapt."

From CBBC -Animals

'Dramatic decline' warning for plants and animals

More than half of common plant species and a third of animals could see a serious decline in their habitat range because of climate change.

Terrible News!

The study looked at the impacts of rising temperatures on nearly 50,000 common species

New research suggests that biodiversity around the globe will be significantly impacted if temperatures rise more than 2C.

But the scientists say that the losses can be reduced if rapid action is taken to curb greenhouse gases.

The paper is published in the journal, Nature Climate Change.

An international team of researchers looked at the impacts of rising temperatures on nearly 50,000 common species of plants and animals.

They looked at both temperature and rainfall records for the habitats that these species now live in and mapped the areas that would remain suitable for them under a number of different climate change scenarios.

The scientists projected that if no significant efforts were made to limit greenhouse gas emissions, 2100 global temperatures would be 4C above pre-industrial levels.

In this model, some 34% of animal species and 57% of plants would lose more than half of their current habitat ranges.

According to Dr Rachel Warren from the University of East Anglia, this would have major impacts for everyone on the planet.

"Our research predicts that climate change will greatly reduce the diversity of even very common species found in most parts of the world. This loss of global-scale biodiversity would significantly impoverish the biosphere and the ecosystem services it provides," she said.

"There will also be a knock-on effect for humans because these species are important for things like water and air purification, flood control, nutrient cycling, and eco-tourism."

The projected impacts on species will be felt more heavily in some parts of the world such as sub-Saharan Africa, Central America, the Amazon region and Australia.

However the researchers say that if global emissions of greenhouse gases are cut rapidly then the impact on biodiversity could be significantly curbed. If global emissions reach their peak in 2016 and temperature rises are held to 2C, then losses could be cut by 60%.

"The good news is that our research provides new evidence of how swift action to reduce CO2 and other greenhouse gases can prevent the biodiversity loss by reducing the amount of global warming to 2C rather than 4 degrees, said Dr Warren.

"This would also buy time – up to four decades - for plants and animals to adapt to the remaining 2 degrees of climate change."

From BBC News- Sci/Environment