Category Archives: Subhra Priyadarsini

Ozone killing enough crops to feed millions of poor

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[http://www.natureasia.com/en/nindia/article/10.1038/nindia.2014.148]

Subhra Priyadarshini

Ozone pollution is destroying 12% of India’s annual cereal production – enough to feed 94 million people below the poverty line through the year. This startling estimate has been revealed in the first ever calculation of ozone pollution in the country¹.

A study by the Indian Institute of Tropical Meteorology (IITM), Pune points a finger at the absence of air quality standards to protect agriculture from ground-level ozone pollution, primarily from vehicles and cooking stoves.

Ground level ozone is the main component of smog and is formed when polluting vehicles, industries or burning matter emit nitrogen oxides, carbon monoxide and volatile organic compounds. These pollutants react with sunlight to form ground level ozone, which is killer for vegetations.

Sachin Ghude

IITM scientist Sachin Ghude and Veerabhadran Ramanathan, a professor of climate and atmospheric sciences at Scripps Institution of Oceanography, at the University of California San Diego carried out the modeling study, supported by emission inventories and crop production data. They quantified the impact of ozone on the yields of cotton, soybeans, rice and wheat crops in India for the year 2005, an year they used as representative of the first decade of the 21st century.

Through the simulation studies, the scientists estimated that wheat was the most impacted crop – every year the country was losing around 3.5 metric tonnes – followed by rice at around 2.1 metric tonnes, mostly in central and north India.

On national scale, this loss is about 12% of the cereals required every year (61.2 Mt) under the provision of recently implemented National Food Security Bill (September-2013) by Government of India, the duo report.

“This study, since it was led by Indian government institutions, should have a major impact on the country’s approach to air pollution mitigation. It should speed up India’s attempts to drastically cut pollution,” Ramanathan told Nature India. High surface ozone concentration over major agriculture regions in India, particularly the Indo-Gangetic Plains, one of the world’s most important fertile agricultural lands is a threat to the country’s food security, the scientists say. They estimate that ozone concentrations will only increase further in the future.

The greatest losses of rice and wheat crops were reported from Maharashtra, Madhya Pradesh, Gujarat, West Bengal and Uttaranchal states.

“The possible ways to minimize these losses is to reduce anthropogenic emissions especially from vehicular and Industrial source and cooking stoves,” Ghude points out. He says another alternative could be to breed ozone-tolerant crops.

Veerabhadran Ramanathan

Ramanathan says some off-the-shelf technologies could be put to use immediately to cut the most damaging pollution – the emission of nitrous oxides from the transportation sector. “This contributes to more than half of the nitrous oxides produced and controlling it would have a major impact in reducing ozone. In so doing, we will also reduce the global warming effect of ozone,” he says.

The study puts India’s economic losses from ozone-induced crop damage at $1.29 billion in 2005, mostly stemming from losses in rice and wheat crops.

References

1. Ghude, S. D. et al. Reductions in India’s crop yield due to ozone. Geophys. Res. Lett.(2014) doi: 10.1002/2014GL060930

New wildfire soot variety could upset all global warming estimates

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[http://www.natureasia.com/en/nindia/article/10.1038/nindia.2014.101]

Subhra Priyadarshini

Soot from wildfires across the world could actually be causing far more warming than our climate models account for. Hidden away from all scientific estimates is a newly-discovered form of soot – the ‘superaggregates’ – emitted from wildfires. Scientists have found that this kind of soot causes 90 per cent more warming than conventional sub-micrometer soot particles.

Current climate models make calculations of wildfire emissions based on sub-micrometer soot particles. The new findings suggest that if we were to reassess the warming from wildfires alone, the figure would go up many times.
The Nagarhole forest wildfire of 2012 that burnt thousands of acres to ashes.
WWT

The superaggregates came into light when scientists from the Desert Research Institute in Nevada-Reno, USA, were studying the massive 2012 wildfire in the Nagarhole National Forest of Karnataka. Studying aerosol samples over the Indian Ocean at the Maldives Climate Observatory on Hanimaadhoo Island, they found a new type of soot particle almost 10 times longer than normal and far more compact in shape than the sub-microscopic variety.

“We call these particles superaggregates because of their super-micron size. Conventional soot particles from diesel vehicles, cook stoves and other ‘contained’ combustion sources are sub-micron size aggregates,” one of the lead researchers Rajan Chakrabarty, presently a faculty member at the Washington University in St. Louis told Nature India.
Though ten times longer than conventional aggregates, the superaggregates have similar mass density. “This means although larger in size, these superaggregates can remain aloft in the atmosphere for the same lifespan (approximately a week) as conventional aggregates,” Chakrabarty said. This also means they get deposited on human lungs the very same way as conventional particles.
According to the scientists, the superaggregate form of soot has not been observed from wildfires before this study.
When they analysed the radiative properties, the scientists found that compared to spherical soot particles, these superaggregates could lead to 90% more warming in the atmosphere.
After detecting soot superaggregates from the 2012 Nagarhole sanctuary fire, the scientists went back to look at smoke samples from the 2010 Millerton Lake fire in Northern California, the 2011 Las Conchas fire in New Mexico, and some more wildfires near Mexico City. Not surprisingly, they found superaggregates in those samples too.
The scientists say though wildfires contribute significantly to global soot emissions, their aerosol formation mechanisms and particle properties are poorly represented in climate models. Superaggregates – previously unrecognized pollutants – could have considerable impact on climate and human health, they add.
“The higher heating effect of these particles, compared to volume-equivalent spheres, could change current estimates of climate forcing by models,” Chakrabarty added. He said multi-front future research in this area could lead to development of mechanical filtration systems to control public health impacts of soot superaggregates during large-scale wildfires.

 

References
1. Chakrabarty, R. K. et al. Soot superaggregates from flaming wildfires and their direct radiative forcing.Sci. Rep. (2014) doi: 10.1038/srep05508

Extra-terrestrial solar event triggered Uttarakhand cloudburst

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[http://www.natureasia.com/en/nindia/article/10.1038/nindia.2014.98]

Subhra Priyadarshini

Unplanned human activities in the Himalayan terrain coupled with some unusual extra-terrestrial events triggered the massive cloudburst over Kedarnath resulting in the catastrophic 2013 floods in Uttarakand region of India, according to new research.

Using NASA satellite data, Saumitra Mukherjee from the School of Environmental Sciences at New Delhi’s Jawaharlal Nehru University (JNU) suggests that a sudden rise in ‘proton flux’ from the Sun was responsible for the catastrophe. The change in land use pattern (such as construction of reservoirs on the Ganges and Alaknanda rivers) added fuel to fire and created havoc in Uttarakhand.
“The rise in proton flux – an unusual solar event where protons emitted by the Sun are accelerated to very high energies – was responsible for the anomalous rise in atmospheric temperature. High concentration of aerosol trapped in the atmosphere and glaciers in Indo-China border initiated a nucleation process in the concentrated water vapour to trigger formation of clouds for the torrential rain and cloud burst on 16 and 17 June 2013,” Mukherjee told Nature India.
Saumitra Mukherjee (right) with SEVAN scientists Karen Arakelyan (left) and David Pokhcaryan (middle)
JNU

NASA’s Sun Observatory Heliospheric Observatory (SOHO) satellite recorded a steep rise in solar proton flux above 10 MeV for 12 days from May 15 to 26). During the same period, the cosmic ray intensity was also recorded at an all-time high at New Delhi’s Jawaharlal Nehru University (JNU), which represents the regional cosmic ray data in the Space Environment Viewing and Analysis Network (SEVAN) of the Asian office of Aerospace Research.

This was just before the anomalous rise in atmospheric temperature in the Himalayan region, which Mukherjee says was initiated by the release of heat energy from the trapped proton drift. “After this event anomalous rise in cosmic ray was recorded. Rise in cosmic rays was instrumental in condensation of the clouds leading to the cloudburst in Kedarnath,” he explains.
The scientist suggests that it took 20 days and 6 hours for the mechanism (of heat transfer to cloud appearance) to initiate the cloudburst in Kedarnath. The heat from the Sun was captured in the ‘Van Allen’s belt’ (between the Sun and Earth), which further accelerated the protons. This extra-terrestrial influence led to rise in temperature to release the aerosol trapped in the glaciers and atmosphere in the Indo-China border to initiate the cloudburst.
Generally, increase in aerosol heating over the Indo-Gangatic plains in the pre-monsoon period leads to a strengthening of the Indian monsoon. The heat transfer from the protons to the atmosphere has affected not only the atmospheric water vapour but has been responsible for melting of glaciers which feed the river Ganges.
Mukherjee says the influence of the Sun, along with anthropogenic activities, on climate change needs more study, especially its manifestation in torrential rains. “This is a radical departure from previous principles but is consistent with existing observations,” he adds.  Mukherjee says his hypothesis does not change the general conclusion that increased proton flux from the Sun reserves trapped heat in geospecific locations which influence temporary change in the atmosphere.
The Kedarnath extreme weather event is a clear manifestation of climate change, he adds.
The devastating flood in Uttarakhand in was a combined impact of cloudburst in Uttarakhand, quick melting of glaciers at high altitude due to beating of ice sheet by raindrops and breaching of natural embankment of Chorabari Tal (north of Kedarnath) due to accumulation of excess surface runoff. Within 48 hours, 280 mm rainfall was recorded and about five feet of snow precipitated at higher altitudes.
Apart from Uttarakhand, Himachal Pradesh, northeast Rajasthan and Delhi also received torrential rainfall. In Delhi, it was an advent of early monsoon that broke the past record of 150 years.

 

References
1. Mukherjee, S. Extra terrestrial remote sensing and geophysical applications to understand Kedarnath cloudburst in Uttarakhand, India. J. Geophys. Remote Sens. (2014) doi:  10.4172/2169-0049.1000124

Climate change policy: What’s new for Asia?

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CDKN-IPCC-Whats-in-it-for-South-Asia-AR5_Page_01At a workshop discussing what the take homes for Asian countries might be from the latest assessment report of the Intergovernmental Panel on Climate Change (IPCC) — AR5 — it was pointed out that there wasn’t enough science coming out of developing countries to feed the database on emissions or warming in the larger climate change debate. Local scientists need to conduct more climate change related experiments, write more scientific papers and bolster regional science in order to make a case for these developing countries in the international discourse on climate change.

“We also need more authors from the developing world to participate in writing the chapters for the IPCC reports,” says Jonathan Lynn, Head of Communication at the IPCC. Lynn says though there is substantial science emanating from India now, some other small Asian countries such as Indonesia lag far behind. The IPCC collates scientific data from across the world to make predictions for future scenarios with the help of scientists, economists, policy makers and government representatives. Most of the work done by scientists in this process is voluntary and not paid for. Developing country scientists, who also do consultancy work for a living, would expect such work to pay off for their time — this could be one of the reasons why not many developing country scientists are interested in the job, Lynn says.

The IPCC assessment reports try to turn all available scientific evidence into something that would make sense to policy makers and businesses — therefore, the authors have explained the science at hand this time in terms of “risk management” parameters. “And since there are questions of ethics and equity involved in this highly political debate, we now have philosophers in the IPCC team to make sure those aspects are taken care of,” Lynn says.

Joyashree Roy, an economist from the Jadavpur University in Kolkata is the lead author of the industry chapter in IPCC’s assessment report five. She says Asia needs to urgently decouple the high energy sector from emissions. “Almost 44 per cent of the global emissions are from the energy and industry sectors of China and India — there lies an opportunity for south Asia. Can we think of a low emission-high energy scenario?”

Roy says population and economic growth are responsible for the surge in energy demand as well as emissions in south Asia.

Another IPCC author Navroz Dubash from New Delhi-based thinktank Centre for Policy Research points to an inherent dichotomy in the report — the number of countries which have adopted mitigation strategies or have a national action plan for climate change has gone up many times, especially in Asia post-2005. Simultaneously, the emission rates of Asia have zoomed and the world as a whole is hurtling at great speed into a carbon-based future. How is that possible, you wonder. “Well, there have been a slew of national policies in the last few years but they will take around 3-4 years to bear fruit. The more optimistic outlook would be to review the scenario in a couple of years and see if these policies have led to significant action,” he says.

Dubash says India will also benefit from the new stand of IPCC where ‘co-benefits’ of climate-friendly policies are being seen in new light. Earlier, IPCC talked of climate change mitigation plans as the main goal with parameters such as development or health as co-benefits. ”The idea now is that the concept of co-benefits could work both ways, meaning if a development project brings in climate change mitigation as a spin-off, it should be totally acceptable. This concept is at the core of India’s national plan and now IPCC has sanctified it — so there’s a huge opportunity.”

According to A R Paneerselvan, advisor to the executive director of Panos South Asia, an organisation informing public and policy debates on environment issues, there are talks of a south Asian intiative for climate related insurance. The insurance would cover farmers against any vulnerability stemming from climate change. The initiative is still at a nascent stage and there’s pressure from the cash crop sector in south Asian countries to make a case for climate-related insurance, he says.

As for IPCC’s fifth assessment report and what’s in it South Asia, London-based Climate and Development Network brought out a good primer that explains just this. The Intergovernmental Panel on Climate Change (IPCC) chairperson Rajendra Kumar Pachauri also spoke about what it means for India at an outreach programme in New Delhi today.

[http://blogs.nature.com/indigenus/2014/08/climate-change-policy-whats-new-for-asia.html]

Good science & good journalism: what’s the link?

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Posted in Indigenus blog

by Subhra Priyadarshini | Category: , ,, , 

In journalism, the more you write about a particular issue, the more chances you have of being heard by people who matter and of impacting public policy — that’s an obvious thing.

In science, the more you publish, the more you influence your peers and, in effect, people who matter. Now, that too is pretty obvious.

In many ways — especially when the issues are of immediate importance to you and me (such as the environment or health) — journalism and scientific publishing have a lot in common. They help create the buzz, bring matters to the fore and, if done well, could influence national policies. In many cases, a glaring scientific observation lends seamlessly to a brilliant work of high-impact journalism and vice-versa.

The latest IPCC working group report (fifth assessment report or AR5), as always and with reason, got a lot of media attention when it was released last month. There have been studies and more studies showing how media coverage of climate change issues peaks during IPCC negotiations and before and after the release of such ARs. However, there’s also much disappointment among negotiators and climate change communicators that effective coverage does not happen where it matters most.

During a south Asian climate change communicators’ meet last year, the issue of journalism versus activism was discussed at length as a section of journalists seemed to be gleefully crossing the line, created by modern journalism, to “do their bit for the society”. Some debated that we live in times when journalism is no longer considered a vocation, it is a profession guided mostly by advertising revenue, circulation/viewership and space/time crunch. However, most agreed that environment journalism is still that niche area where these lines often blur effortlessly.

Award winning environmental journalist Mark Schapiro says science lends itself seamlessly to great investigative stories.

The sentiments were echoed this month when a meet of global investigative journalists discussed how environmental journalism could be made more scientific and high-impact. The session discussed at length the many layers of environmental coverage, the use of scientific methodology and new age tools (satellite images, scientific literature and geotagged maps) to make sense of it all.

Taking this discussion to the next level — that is to ask ‘how environment journalists can make a difference’ — David Dodman of London-based International Institute of Environment and Development recently outlined what journalists in their role as communicators can do towards “strengthening the resilience of vulnerable citizens and infrastructure.”  They could advocate wise use of funds to improve living conditions and build resilience.

Dodman says urban populations in Africa and Asia live in places exposed to hazards, such as floods and tropical storms, which will become more frequent and intense in the coming decades. Many towns and cities lack the necessary basic infrastructure and resources to reduce the risk that such hazards pose,” he wrote in his blog. Urban residents are not always aware of the range of funds that their cities could use. Journalists can inform vulnerable citizens about them, so that citizens can in turn make the right demands from their authorities at different scales, he says.

A couple of months ago, an article in Nature Reviews Climate Change made a direct connection between pollution in a particular country/region to the number of scientific papers published in that country/region. The article accompanied by a beautiful map  concluded that the more the number of scientific papers produced from a country, the lesser are its pollution levels. “Good scientific research is necessary to provide the basis for the implementation of policies that aim to control harmful environmental agents, helping society to decide a course of action,” write Lais Fajersztain and colleagues in the paper.

They also infer from their study that governments that spend more on health care have more stringent air quality standards, probably because of greater governmental awareness of the adverse health effects of air pollution and the consequent establishment of air pollution control measures to avoid increased health costs. The researchers found that scientific research on the impact of air pollution on health is concentrated mainly in North America and Europe, China, Australia, Brazil and Japan. Such research is practically nonexistent in Africa, India and other South American countries — developing countries were found to contribute only 5% of the total research.

The map depicted a comparative panel of the number of papers produced from 1983 to date on malaria, water quality and air pollution, using the Web of Science database. “There was a marked imbalance between levels of air pollution and local scientific production: a more balanced scenario emerges when waterborne diseases and malaria are considered,” the scientists wrote.

Now that is something to pick on. And it brings to fore another question: are countries traditionally doing well in science also producing the best journalistic works? The question, in turn, merits another scientific study.

Good science and good journalism will never cease to give-and-take.

Funerals, weddings skew South Asia emission figures

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[doi:10.1038/nindia.2013.137; Published online 19 October 2013]

Subhra Priyadarshini

Across South Asia, a disturbing and hitherto unaccounted amount of smoke is making its way stealthily into the air — the kind of smoke people chose to revere, inhale and quietly ignore. This is the smoke from tonnes of incense sticks in temples, mosques and graveyards as also from burning the dead in open funeral pyres. The smoke has been adding significantly to the region’s ‘brown carbon’ and ‘volatile organic compound’ emissions but remains completely missing from national health indices or international climate models.

A researcher measures brown carbon emissions at an open air cremation site in Chattisgarh, India. © PRSU

 

Scientists from Pandit Ravishankar Shukla University (PRSU) in Raipur, Chattisgarh along with colleagues from the Desert Research Institute (DRI) in Reno, Nevada, USA have now accounted for the first time how much these religious practices are actually contributing to national emissions in the region 1, 2.

It turns out that the funeral pyres alone could be contributing as much as 92 Gg/year (green house gas emissions per year) of light-absorbing carbon aerosols. This, they say, is equivalent to almost 23 percent of the total carbonaceous aerosol mass produced by human-burnt fossil fuels, and 10 percent of biofuels in the South Asian region.

Additionally, samples collected from marriage ceremonies, Muslim graveyards, Hindu and Buddhist temples in Chattisgarh state of India indicate emissions of massive quantities of carcinogenic volatile organic compounds (VOC). Extrapolated to a national scale, the figures turn out to be 0.001 Terra grams per year (Tg/yr), which the scientists term as ‘very huge’. (Total VOC emission estimate from all ritual activities was found to be 7.388 Tg/year out of which crematoria alone contributed 7.387 Tg/year).

Says Rajan Chakrabarty from DRI,” Our main motivation to investigate funeral pyres and widely-prevalent cultural practices in India stemmed from the lack of data about these emission sources in current regional emission inventories used by global climate models. Current inventories include pollutants primarily from technology-based (or energy production) sources such as fossil fuel and residential biofuel burning.”

Hence, when Shamsh Pervez from the PRSU in Chattisgarh visited DRI as a Fulbright fellow in 2011, the laid out the blueprint for the study. Their investigations began when Pervez returned to India.

An interesting thing the team found in funeral pyres were the organic carbon particles (and not black carbon) as primary emitters. These absorb sunlight and caused heating. “Conventional organic carbon aerosols are treated in climate models as non-absorbing in the visible spectrum. This class of light-absorbing organic carbon is known as brown carbon aerosols”, Chakrabarty says.

Their study on funeral pyre emissions in India and Nepal pointed out that over South Asia, one could expect not just black carbon (or soot) but brown carbon also playing a major warming effect and subsequently impacting the climate.

“We need to study this better to understand the effects of brown carbon and climate impacts over South Asia from previously non-inventoried and unstudied sources,” he points out.

Carbon aerosols are known to be the second largest anthropogenic contributor to global warming after carbon dioxide. The dark particles settling on snow make snow covers absorb more sunlight and accelerate glacial melting. Chakrabarty’s earlier work in the north-east Indian city of Guwahati revealed that alarmingly high pollution levels in the Brahmaputra river might be resulting in an outflow of pollutants into the Himalayas, melting glaciers faster and interfering with India’s monsoon cycle 3.

Between 2011 and 2012, Pervez and his colleagues hopped from marriage ceremonies to graveyards and temples to shrines in Raipur city measuring what they call the ’emission factors’ of plumes from embers and flames. Alongside the regular incense, they found people burning barks of mango and sal (Shorea rodusta) trees, cow dung, cow urine, dry leaves, oil, vermillion powder, camphor, ghee (clarified butter), cotton and grains in these rituals. The scientists then measured fourteen deadly volatile organic compounds from these samples including formaldehyde, benzene, styrene and 1, 3 butadiene.

“There are three million religious places of worship in India alone and over 10 million marriages take place every year in this country according to the 2011 census. When these results were multiplied to fit these scales, the quantum of emissions was just baffling,” Pervez told Nature India.

The scientists feel they have to tread cautiously in suggesting mitigation measures for religious practices-induced warming and health hazards since these are deeply-entrenched and culturally sensitive issues. “No wonder the cases of chronic bronchitis and lung cancer are much higher among people conducting these religious practices but that, of course, is a matter of another scientific study,” Pervez says.

He says it is possible, however, to inculcate climate and health-friendly practices among people without hurting their religious sentiments. “For example, this month during the religious Hindu festival of Sharad Purnima, which involves cooking kheer(a sweetmeat) in the open and keeping it in the open overnight in the belief that it turns into nectar in the auspicious full moon light, we advocated that people cover it with transparent sheets. It would mean that moonlight does reach the kheer and at the same time it remains untouched by the heavy load of pollutants in the Chattisgarh air.”

The advocacy bore fruit and people have taken to the practice well, Pervez says. Similarly, for religious burning practices he suggests making a start by shunning all synthetic burning materials and sticking to safer biomaterials such as wood. As of now, using the most recent Hindu and Sikh population death-rate data, they estimate that more than four tera grams of burning material is used annually in India and Nepal, with the highest amount being used in the Indo-Gangetic plains and western Indian states.

  • References

    1. Chakrabarty, R. K. et al. Funeral pyres in South Asia: brown carbon aerosol emissions and climate impacts. Environ. Sci. Tech. doi: 10.1021/ez4000669(2013)
    2. Dewangan, S. et al. Emission of volatile organic compounds from religious and ritual activities in India. Environ. Monit. Assess. doi: 10.1007/s10661-013-3250-z (2013)
    3. Chakrabarty, R. K. et al. Strong radiative heating due to wintertime black carbon aerosols in the Brahmaputra River Valley. Geophys. Res. Lett. doi:10.1029/2012GL051148 (2012)

Aerosols contributing to climate change in China, India

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[Read the Nature India blog Indigenus here: http://blogs.nature.com/indigenus/2013/08/aerosols-contributing-to-climate-change-in-india-china.html]

Researchers have found that these small airborne particles called aerosols (for example, black carbon particles in diesel exhaust and sulfate particles produced by coal burning) in India and China may indirectly contribute to climate change. Higher black carbon levels in the atmosphere lead to warming, whereas increased sulfate levels cause cooling.

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Higher risk of flooding fuels demand for South Asia water charter

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[Full story: http://www.nature.com/nindia/2013/130613/full/nindia.2013.79.html]

Subhra Priyadarshini

A new global study1 predicting flood risks due to climate change has put South Asia and peninsular India under high risk prompting the region’s scientists and policy makers to call for an urgent look at the ‘ad-hoc’ national flood management policies and, more importantly, cross border water issues. The demand, specifically, for a south Asia charter on water to meet the projected higher risks, is set to gain new ground in the region.

The alarm bells

The mega study relies on 11 climate models for the first time to project global flood risk for the end of this century when the climate is predicted to get warmer. Through a state-of-the-art global river routing model (called the Catchment-based Macro-scale Floodplain Model or CaMa-Flood), Japanese and British scientists have demonstrated a large increase in flood frequency in Southeast Asia, peninsular India, eastern Africa and the northern half of the Andes.

Lead researcher Yukiko Hirabayashi from the Institute of Engineering Innovation at The University of Tokyo says the team looked at changes in flooding and evaluated its consistency and spread. Their study predicts a large increase in flood frequency in parts of Asia, Africa and South America in response to future warming conditions. These findings suggest that there is a necessity for adaptation to intensified floods and the introduction of further strategies to mitigate greenhouse gas emissions, Hirabayashi says.

However, the study also projects a decrease in flood frequency in certain areas of the world — northern and Eastern Europe, Anatolia, Central Asia, central North America and southern South America.

In addition to the global-scale analysis, the models were studied at the outlets of selected river basins. The models suggest that during the 21st century, the frequency of floods will increase in almost all of the selected rivers in South Asia, Southeast Asia, Oceania, Africa and Northeast Eurasia. They also project that the 20th century 100-year flood event will occur about every 10–50 years in many of these rivers in the 21st century.

The authors caution that global exposure to floods would increase depending on the degree of warming, but interannual variability of the exposure may imply the necessity of adaptation before significant warming. They highlight that major attention should be paid to adaptation and mitigation strategies in lower-latitude countries where flood frequency and population are both projected to increase.

Analysing the danger

Hirabayashi’s co-researcher Shinjiro Kanae from the Department of Civil Engineering at the Tokyo Institute of Technology says according to the summary of the IPCC special report SREX (2012) on the projection of future floods the “projected precipitation and temperature changes imply possible changes in floods, although overall there is low confidence in projections of changes in fluvial floods. Confidence is low due to limited evidence and because the causes of regional changes are complex….”

Kanae, who was involved in the writing the SREX summary, says the evidence was pretty limited when it was written last year but their new projection increases the level of evidence to a higher level.

“The so-called warm, humid regions (including Southeast Asia, East Asia, South Asia and tropical Africa) are already notoriously flood-prone. Unfortunately, many countries in these regions are developing. Also, population is likely to increase in some or many of them according to UN estimates. It’s a really ‘damp prospect’ for them,” he says.

Rajiv Sinha, professor of geosciences in the department of civil engineering at IIT Kanpur, says climate change can involve marked changes in the probability distribution of weather parameters (temperature and precipitation) and is likely to modify the magnitude-frequency relationship of the geomorphic processes.

“A series of unprecedented floods in several parts of India should force us to think that extreme events can and do occur. They should trigger serious thought that natural as well as anthropogenic forces are often not easy to separate,” Sinha says. He says some recent floods in India — Himachal Pradesh (July 2010), Leh (August 2010), several parts of Karnataka, Tamil Nadu, Andhra Pradesh and south Orissa during November-December 2010 — should serve as an indicator to a modified hydrological regime.

Globally too, severe floods in east China (May 2010); Rio Lorogo, Brazil (June 2010); Pakistan (August 2010) and Queensland, Australia (December 2010); Rio de Janeiro, Brazil (January, 2011); and Queensland, Australia (February, 2011) point towards this, he says.

Scientific analysis of archived data and model-simulated precipitation fields show that there is some increase in extreme rainfall events of high intensity and short duration rainfall in the last 50 years or so, according to Sushil Kumar Dash, head of the Centre for Atmospheric Sciences at IIT Delhi. “Such incidents are also likely to occur more in the future. These extreme rainfall incidents will most probably increase the chances of more flash floods and urban flooding in India,” he says.

Dash says atmospheric warming has impact on snow melting. The water level of the three most important rivers of India may remain higher in summer due to increased snow melting and this might lead to more flooding, he adds.

Science versus policy

But dependence on scientific studies to steer policy in South Asia is virtually nil, says Mashfiqus Salehin, a professor at the Institute of Water and Flood Management (IWFM) in Dhaka-based Bangladesh University of Engineering and Technology. “We have extremely ill planned, ad-hoc and temporary flood control projects — thousands of kilometres of embankments get breached every year.” Bangladesh’s mighty braided river Jamuna has close to 13,000 hectares of embankments, which are breached regularly due to increase in extreme flood events in recent times.

Salehin says 68 per cent of the Ganga-Bramhaputra-Meghna basin lies in Assam, West Bengal, Bihar and Uttar Pradesh states of India. The Ganges has a very high damage potential, especially in Uttar Pradesh and Bihar, he cautions.

Assam’s Bramhaputra valley represents one of the most acutely hazard-prone regions in India having a total flood-prone area of 3.2 mega hectares. It is time the flood-prone countries in south Asia learnt from flood management experience and basin level integration from one another. “For instance, Bangladesh needs knowledge on the effect of hydel projects in India and China since those very rivers come to this country. But sadly, there’s no clarity on trans-boundary water cooperation between the countries,” Salehin points out.

He cites the example of the barrages over river Teesta constructed on either side of the Indo-Bangladesh border without bilateral consultation. The joint river commission between India and Bangladesh has also not been very conclusive in its long years of discourse, he points out.

In fact, in 2008, the Indo-Bangladesh Joint River Commission had rued the lack of information between the two countries and poor availability of rainfall data across borders, says Istiak Sobhan, Programme Coordinator of the IUCN Bangladesh country office. “Ironically, India and Bangladesh rely more on US satellite maps for flood impact assessment rather than data from one another,” he points out. Flood forecasting, therefore, becomes very problematic for Bangladesh since real time data from upstream Meghalaya and Assam is not available, especially during flash floods.

Sobhan says hydrogeological changes along this stretch also determine the flood intensity and frequency but data on this is also largely insufficient.

Power play and water politics

The heightened risk of flooding in south Asia can only be tackled if countries press for a common south Asia charter on water, something like the SAARC charter of democracy, says Imtiaz Ahmed, professor of international relations at the University of Dhaka. “The issue across south Asia is that it is very easy to be a nationalist but very difficult to be a south Asian,” he points out. Ahmed says water politics has traditionally been governed by territoriality, colonised ‘developmentality’ and a nationalised identity of water.

“That is not going to work in favour of nations in the new paradigm that predicts worse flooding scenario in south Asia,” Ahmed says.

Rohan D’souza, an assistant professor at Delhi-based Jawaharlal Nehru University’s Centre for Studies in Science Policy says in South Asia, flood control has traditionally been given ‘structural engineering’ responses, such as large dams and embankments. “The belief was that a river’s flow could either be stored in huge reservoirs or kept firmly contained within its channel by having the banks walled on both sides.” This approach has been replaced in recent years by flood management policies that involve tactical retreats from the river bed to some structural engineering efforts that can contain the river.

Analysing the subcontinent’s vulnerability, he says South Asia lives with the dramatic changes brought about by its many colonial hydraulic legacies. “Throughout the latter half of the 20th century, flood control has often been the immediate and central response of the governments to recurring floods. The long history and the complex collection of practices for flood utilization — be it in the form of cropping strategies, unique plant varieties and even prudent location strategies — has been forgotten and deleted from the memory of official water management policies,” he rues.

D’souza echoes Ahmed’s demand for a regional water charter. “I entirely subscribe to the idea of a south Asia water charter. It is the need of the hour.”

References

    1. Hirabayashi, Y. et al. Global flood risk under climate change. Nat. Climate Change. (2013) doi: 10.1038/NCLIMATE1911