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The Indian sub-continent may lose close to 14,000 sq.km. of land with the rise of a one metre of sea level due to climate change.

“Total area loss due to marine intrusion into coastal areas of the Indian sub-continent is estimated at approximately 13,973 sq.km. and 60,497 sq. km. of land area under 1m (metre) and 6m sea-level rise scenarios, respectively,” says a report published in the latest issue of Journal of Threatened Taxa.

Prepared by a group of ecologists led by Dr M Zafar-ul Islam, the study presents an overview of the potential consequences of 1m and 6m sea-level rise for coastal conservation areas on the Indian sub-continent.

Sea level is rising due to thermal expansion of the ocean, mountain glacier melting, and discharge from ice sheets as a result of global warming.

Several coastal eco-regions and conservation areas are predicted to lose over half of their land areas to marine intrusion, particularly under the 6m sea level rise scenario.

The report warns that marine intrusion might affect 18 of the 48 eco-regions in India.

“Under the 1m sea level rise scenario, estimates of eco-region inundation range from 19 per cent to 59 per cent. While under the 6m sea-level rise scenario, estimates of eco-region inundation range from 27-58 per cent,” it says.

Under the 1m sea level rise scenario, the Godavari-Krishna mangrove eco-region is predicted to lose more than a quarter of its area, while the UNESCO World Heritage site of Sundarbans in West Bengal is predicted to lose more than half of its area.

While under the 6m sea level rise scenario, three eco-regions (Sundarbans freshwater swamp forests, Andaman Islands rain forests and Maldives Lakshadweep-Chagos Archipelago tropical moist forest) are predicted to lose more than a quarter of their land areas.

Three more (Sundarbans mangroves, Godavari-Krishna mangroves, and Rann of Kutch seasonal salt marsh) are predicted to lose more than half of their land area.

Seven protected areas — Bhitarkanika, Chilka Lake, Point Calimere, Interview Island, Lothian Island, Sajnakhali and Pulicat Lake — are expected to experience more than 50 per cent inundation under 1m sea level rise, and an additional four protected areas — Kachchh Desert, Velavadar, Pulicat, and Nal Sarovar — join this list under 6m sea level rise.

Out of the 22 coastal conservation areas, nine will be spared from the effects of marine intrusion under 1m sea-level rise, but only one will be spared under a 6m sea-level rise scenario, says the report.

Hundreds of species of flora and fauna, including globally threatened species, depend upon low-lying coastal eco-systems for their survival.

Several important biodiversity areas, including in particular protected and non-protected IBAs (Important Bird Areas) in the Bay of Bengal and Arabian Sea, have already been stressed by numerous anthropogenic impacts as well as by invasive species.

News

Queensland property values at risk as sea levels rise due to climate change, CSIRO and University of Queensland say

• by: Peter Hall
• From: The Courier-Mail
• June 18, 2013 12:00AM

RISING sea levels and intense storms will cut thousands of dollars from the value of low-lying homes in southeast Queensland, including Brisbane, according to an Australia-first climate change study.

Published in Geology, new research led by Monash University geologists has detected the first evidence that a passive margin in the Atlantic ocean is becoming active. Subduction zones, such as the one beginning near Iberia, are areas where one of the tectonic plates that cover Earth’s surface dives beneath another plate into the mantle — the layer just below the crust.

Lead author Dr João Duarte, from the School of Geosciences said the team mapped the ocean floor and found it was beginning to fracture, indicating tectonic activity around the apparently passive South West Iberia plate margin.

“What we have detected is the very beginnings of an active margin — it’s like an embryonic subduction zone,” Dr Duarte said.

“Significant earthquake activity, including the 1755 quake which devastated Lisbon, indicated that there might be convergent tectonic movement in the area. For the first time, we have been able to provide not only evidences that this is indeed the case, but also a consistent driving mechanism.”

The incipient subduction in the Iberian zone could signal the start of a new phase of the Wilson Cycle — where plate movements break up supercontinents, like Pangaea, and open oceans, stabilise and then form new subduction zones which close the oceans and bring the scattered continents back together.

This break-up and reformation of supercontinents has happened at least three times, over more than four billion years, on Earth. The Iberian subduction will gradually pull Iberia towards the United States over approximately 220 million years.

The findings provide a unique opportunity to observe a passive margin becoming active — a process that will take around 20 million years. Even at this early phase the site will yield data that is crucial to refining the geodynamic models.

“Understanding these processes will certainly provide new insights on how subduction zones may have initiated in the past and how oceans start to close,” Dr Duarte said.

An international team led by Professor Edward Hanna from the University of Sheffield’s Department of Geography used a computer model simulation (called SnowModel) and satellite data to confirm a record surface melting of the GrIS for at least the last 50 years — when on 11 July 2012, more than 90 percent of the ice-sheet surface melted. This far exceeded the previous surface melt extent record of 52 percent in 2010.

The team also analysed weather station data from on top of and around the GrIS, largely collected by the Danish Meteorological Institute but also by US programmes, which showed that several new high Greenland temperature records were set in summer 2012.

The research, published today in the International Journal of Climatology, clearly demonstrates that the record surface melting of the GrIS was mainly caused by highly unusual atmospheric circulation and jet stream changes, which were also responsible for last summer’s unusually wet weather in England.

The analysis shows that ocean temperatures and Arctic sea-ice cover were relatively unimportant factors in causing the extra Greenland melt.

Professor Hanna said: “The GrIS is a highly sensitive indicator of regional and global climate change, and has been undergoing rapid warming and mass loss during the last 5-20 years. Much attention has been given to the NASA announcement of record surface melting of the GrIS in mid-July 2012. This event was unprecedented in the satellite record of observations dating back to the 1970s and probably unlikely to have occurred previously for well over a century.

“Our research found that a ‘heat dome’ of warm southerly winds over the ice sheet led to widespread surface melting. These jet stream changes over Greenland do not seem to be well captured in the latest Intergovernmental Panel on Climate Change (IPCC) computer model predictions of climate change, and this may indicate a deficiency in these models. According to our current understanding, the unusual atmospheric circulation and consequent warm conditions of summer 2012 do not appear to be climatically representative of future ‘average’ summers predicted later this century.

“Taken together, our present results strongly suggest that the main forcing of the extreme GrIS surface melt in July 2012 was atmospheric, linked with changes in the summer North Atlantic Oscillation (NAO), Greenland Blocking Index (GBI, a high pressure system centred over Greenland) and polar jet stream which favoured southerly warm air advection along the western coast.

“The next five-10 years will reveal whether or not 2012 was a rare event resulting from the natural variability of the NAO or part of an emerging pattern of new extreme high melt years. Because such atmospheric, and resulting GrIS surface climate, changes are not well projected by the current generation of global climate models, it is currently very hard to predict future changes in Greenland climate. Yet it is crucial to understand such changes much better if we are to have any hope of reliably predicting future changes in GrIS mass balance, which is likely to be a dominant contributor to global sea-level change over the next 100-1000 years.”