Washington: A recent study has revealed that rapid climatic changes, combined with increasing population, economic growth and land subsidence, could cause global flood losses worth 52 billion dollars by 2050. 'Future Flood Losses in Major Coastal Cities' is part of an ongoing project by the Organisation for Economic Co-operation and Development (OECD) to explore the policy implications of flood risks due to climate change and economic development. Average global flood losses in 2005 that was estimated at about US 6 billion dollars per year could see more than nine-fold increase in the global risk of floods in large port cities between now and 2050 with projected socio-economic change, the researchers said.
The cities that were ranked most 'at risk' today among those of 136, as measured by annual average losses due to floods, includes: Guangzhou, Miami, New York, New Orleans, Mumbai, Nagoya, Tampa-St. Petersburg, Boston, Shenzen, Osaka-Kobe, and Vancouver.
The United States and China were among the countries at greatest risk from coastal city flooding, the study added.
Miami, New York City and New Orleans are the three American cities that were held responsible for 31 per cent of the losses across the 136 cities due to their high wealth and low protection level.
Adding Guangzhou, the four top cities explained 43 per cent of global losses as of 2005.
The study has also found out that because flood defences have been designed for past conditions, even a moderate rise in sea-level would lead to soaring losses in the absence of adaptation.
Meanwhile, coastal cities will have to improve their flood management, including better defences, at a cost estimated around US 50 billion dollars per year for the 136 cities.
According to Dr Stephane Hallegatte, from the World Bank and lead author of the study, 'There is a limit to what can be achieved with hard protection. Populations and assets will remain vulnerable to defence failures or to exceptional events that exceed the protection design.'
Hence, policy makers should consider early warning systems, evacuation planning, more resilient infrastructure and financial support to rebuild economies and help cities deal with disasters, when they do hit.
Source: ANI
LONDON: Rising ocean temperatures will upset natural cycles of carbon dioxide, nitrogen and phosphorous, a new study has warned
Plankton plays an important role in the ocean's carbon cycle by removing half of all CO2 from the atmosphere during photosynthesis and storing it deep under the sea — isolated from the atmosphere for centuries.
The study from the University of East Anglia shows that water temperature has a direct impact on maintaining the delicate plankton ecosystem of our oceans.
The new research means that ocean warming will impact plankton, and in turn drive a vicious cycle of climate change.
Researchers investigated phytoplankton — microscopic plant-like organisms that rely on photosynthesis to reproduce and grow.
"Phytoplanktons, including micro-algae, are responsible for half of the carbon dioxide that is naturally removed from the atmosphere. As well as being vital to climate control, it also creates enough oxygen for every other breath we take, and forms the base of the food chain for fisheries so it is incredibly important for food security," lead researcher Dr Thomas Mock, said.
"Previous studies have shown that phytoplankton communities respond to global warming by changes in diversity and productivity. But with our study we show that warmer temperatures directly impact the chemical cycles in plankton, which has not been shown before," said Mock.
Collaborators from the University of Exeter, who are co-authors of this study, developed computer generated models to create a global ecosystem model that took into account world ocean temperatures, 1.5 million plankton DNA sequences taken from samples, and biochemical data.
"We found that temperature plays a critical role in driving the cycling of chemicals in marine micro-algae. It affects these reactions as much as nutrients and light, which was not known before," said Mock.
"Under warmer temperatures, marine micro-algae do not seem to produce as many ribosomes as under lower temperatures. Ribosomes join up the building blocks of proteins in cells. They are rich in phosphorous and if they are being reduced, this will produce higher ratios of nitrogen compared to phosphorous, increasing the demand for nitrogen in the oceans.
"This will eventually lead to a greater prevalence of blue-green algae called cyanobacteria which fix atmospheric nitrogen," he added.
The study was published in the journal Nature Climate Change.
Source: PTI
