Climate change heralds thirsty times ahead for most

A new modelling study suggests that increasing temperatures will dramatically affect the world's great rivers

Veteran climate modeller Syukuro Manabe, and colleagues at Princeton University, modelled what effect a quadrupling of atmospheric carbon dioxide above pre-industrial levels would have on the global hydrological (water) cycle over the next 300 years. That looks further ahead than most climate models, but the scenario is inevitable unless governments take drastic action to limit greenhouse gas emissions. Rising CO2 levels will trigger higher temperatures not only at the Earth's surface, but also in the troposphere, the team says. By factoring this into the models together with changes to levels of water vapour, cloud cover, solar radiation and ozone, the team predicted the effect that climate changes could have on evaporation and precipitation (rain). Both would increase, the researchers found, causing the discharge of fresh water from rivers around the world to rise by almost 15 per cent.

However, while water is going to be more plentiful in regions that already have plenty, the net effect will be to take the world's water further from where the people are. 'Water stresses will increase significantly in regions that are already relatively dry,' Manabe reports in the journal Climate Change. He goes on to predict that evaporation will reduce the moisture content of soils in many semi-arid parts of the world, including north-east China, the grasslands of Africa, the Mediterranean and the southern and western coasts of Australia. Soil moisture will fall by up to 40 per cent in southern US states, representing the greatest reduction.

The effects on the world's rivers will be just as dramatic. The biggest increases will be in the far north of Canada and Russia. For instance, the flow of river Ob in Siberia is projected to increase by 42 per cent by the end of the 23rd century. This prediction could encourage Russia's plans to divert Siberian rivers to irrigate the deserts around the Aral Sea. Similar changes could increase pressure from the US for Canada to allow transfers from its giant Pacific rivers to water the American West. Manabe predicts a 47 per cent increase in the flow of the Yukon river.

By contrast, there will be lover flows in many mid-latitude rivers, which run through heavily populated regions. Those that will start to decline include the Mississippi, Mekong and especially the Nile, one of the world's most heavily used and politically contested rivers, where his model predicts an 18 per cent fall in flow.

The changes will present a 'profound challenge' to the world's water managers, Manabe says. They are also likely to fuel calls for a new generation of super-dams and canals to move water round the planet, like China's current scheme to transfer water between north and south. Some of the findings are controversial. The UK Meteorological Office's climate model predicts that flows in the Amazon could fall this century, while Manabe's team predicts greater rainfall could increase its flow by 23 per cent. And while Manabe foresees a 49 per cent increase in the flow of the Ganges and Brahmaputra rivers that drain the Himalayas, an international study reported that the Ganges would lose flow as the glaciers that feed it melt away.

Global warming has already increased glacier melting by up to 30 per cent. 'After 40 years, most of the glaciers will be wiped out and then we will have severe water problems,' says Syed Iqbal Hasnain of Calicut University, Kerala, reporting the results of a three-year study by British, Indian and Nepalese researchers. The study finds the biggest impact in Pakistan, where the River Indus irrigates half the country's crops. Flows here could double before crashing to less than half current levels by the end of the century. But the declining flows predicted for the Ganges will also throw into disarray a vast Indian government scheme to avoid drought by diverting water from the country's glacier-fed northern rivers to the arid south.

Meanwhile, a team of researchers in France say that climate change is already affecting the world's rivers. David Labat and colleagues at the government's CNRS research agency in Toulouse in France reconstructed the monthly discharges of more than 200 of the world's largest rivers since 1875. They took discharge data held by the Global Runoff Data Centre in Germany and the UNESCO River Discharge Database and used a statistical technique to fill in gaps left by missing data, or changes to run-off caused by dams and irrigation projects.

Their findings reveal that changing temperatures cause river flows to rise and fall after a delay of approximately 15 years, and the team predicts that global flows will increase by about 4 per cent for every 1°C rise in global temperature. However, climate change over the past few decades has already caused discharge from rivers in North and South America and Asia to increase. Run-off in Europe has remained stable, but the flow of water from Africa's rivers has fallen.

Climate change heralds thirsty times ahead for most

A new modelling study suggests that increasing temperatures will dramatically affect the world's great rivers

Veteran climate modeller Syukuro Manabe, and colleagues at Princeton University, modelled what effect a quadrupling of atmospheric carbon dioxide above pre-industrial levels would have on the global hydrological (water) cycle over the next 300 years. That looks further ahead than most climate models, but the scenario is inevitable unless governments take drastic action to limit greenhouse gas emissions. Rising CO2 levels will trigger higher temperatures not only at the Earth's surface, but also in the troposphere, the team says. By factoring this into the models together with changes to levels of water vapour, cloud cover, solar radiation and ozone, the team predicted the effect that climate changes could have on evaporation and precipitation (rain). Both would increase, the researchers found, causing the discharge of fresh water from rivers around the world to rise by almost 15 per cent.

However, while water is going to be more plentiful in regions that already have plenty, the net effect will be to take the world's water further from where the people are. 'Water stresses will increase significantly in regions that are already relatively dry,' Manabe reports in the journal Climate Change. He goes on to predict that evaporation will reduce the moisture content of soils in many semi-arid parts of the world, including north-east China, the grasslands of Africa, the Mediterranean and the southern and western coasts of Australia. Soil moisture will fall by up to 40 per cent in southern US states, representing the greatest reduction.

The effects on the world's rivers will be just as dramatic. The biggest increases will be in the far north of Canada and Russia. For instance, the flow of river Ob in Siberia is projected to increase by 42 per cent by the end of the 23rd century. This prediction could encourage Russia's plans to divert Siberian rivers to irrigate the deserts around the Aral Sea. Similar changes could increase pressure from the US for Canada to allow transfers from its giant Pacific rivers to water the American West. Manabe predicts a 47 per cent increase in the flow of the Yukon river.

By contrast, there will be lover flows in many mid-latitude rivers, which run through heavily populated regions. Those that will start to decline include the Mississippi, Mekong and especially the Nile, one of the world's most heavily used and politically contested rivers, where his model predicts an 18 per cent fall in flow.

The changes will present a 'profound challenge' to the world's water managers, Manabe says. They are also likely to fuel calls for a new generation of super-dams and canals to move water round the planet, like China's current scheme to transfer water between north and south. Some of the findings are controversial. The UK Meteorological Office's climate model predicts that flows in the Amazon could fall this century, while Manabe's team predicts greater rainfall could increase its flow by 23 per cent. And while Manabe foresees a 49 per cent increase in the flow of the Ganges and Brahmaputra rivers that drain the Himalayas, an international study reported that the Ganges would lose flow as the glaciers that feed it melt away.

Global warming has already increased glacier melting by up to 30 per cent. 'After 40 years, most of the glaciers will be wiped out and then we will have severe water problems,' says Syed Iqbal Hasnain of Calicut University, Kerala, reporting the results of a three-year study by British, Indian and Nepalese researchers. The study finds the biggest impact in Pakistan, where the River Indus irrigates half the country's crops. Flows here could double before crashing to less than half current levels by the end of the century. But the declining flows predicted for the Ganges will also throw into disarray a vast Indian government scheme to avoid drought by diverting water from the country's glacier-fed northern rivers to the arid south.

Meanwhile, a team of researchers in France say that climate change is already affecting the world's rivers. David Labat and colleagues at the government's CNRS research agency in Toulouse in France reconstructed the monthly discharges of more than 200 of the world's largest rivers since 1875. They took discharge data held by the Global Runoff Data Centre in Germany and the UNESCO River Discharge Database and used a statistical technique to fill in gaps left by missing data, or changes to run-off caused by dams and irrigation projects.

Their findings reveal that changing temperatures cause river flows to rise and fall after a delay of approximately 15 years, and the team predicts that global flows will increase by about 4 per cent for every 1°C rise in global temperature. However, climate change over the past few decades has already caused discharge from rivers in North and South America and Asia to increase. Run-off in Europe has remained stable, but the flow of water from Africa's rivers has fallen.

Climate change heralds thirsty times ahead for most

A new modelling study suggests that increasing temperatures will dramatically affect the world's great rivers

Veteran climate modeller Syukuro Manabe, and colleagues at Princeton University, modelled what effect a quadrupling of atmospheric carbon dioxide above pre-industrial levels would have on the global hydrological (water) cycle over the next 300 years. That looks further ahead than most climate models, but the scenario is inevitable unless governments take drastic action to limit greenhouse gas emissions. Rising CO2 levels will trigger higher temperatures not only at the Earth's surface, but also in the troposphere, the team says. By factoring this into the models together with changes to levels of water vapour, cloud cover, solar radiation and ozone, the team predicted the effect that climate changes could have on evaporation and precipitation (rain). Both would increase, the researchers found, causing the discharge of fresh water from rivers around the world to rise by almost 15 per cent.

However, while water is going to be more plentiful in regions that already have plenty, the net effect will be to take the world's water further from where the people are. 'Water stresses will increase significantly in regions that are already relatively dry,' Manabe reports in the journal Climate Change. He goes on to predict that evaporation will reduce the moisture content of soils in many semi-arid parts of the world, including north-east China, the grasslands of Africa, the Mediterranean and the southern and western coasts of Australia. Soil moisture will fall by up to 40 per cent in southern US states, representing the greatest reduction.

The effects on the world's rivers will be just as dramatic. The biggest increases will be in the far north of Canada and Russia. For instance, the flow of river Ob in Siberia is projected to increase by 42 per cent by the end of the 23rd century. This prediction could encourage Russia's plans to divert Siberian rivers to irrigate the deserts around the Aral Sea. Similar changes could increase pressure from the US for Canada to allow transfers from its giant Pacific rivers to water the American West. Manabe predicts a 47 per cent increase in the flow of the Yukon river.

By contrast, there will be lover flows in many mid-latitude rivers, which run through heavily populated regions. Those that will start to decline include the Mississippi, Mekong and especially the Nile, one of the world's most heavily used and politically contested rivers, where his model predicts an 18 per cent fall in flow.

The changes will present a 'profound challenge' to the world's water managers, Manabe says. They are also likely to fuel calls for a new generation of super-dams and canals to move water round the planet, like China's current scheme to transfer water between north and south. Some of the findings are controversial. The UK Meteorological Office's climate model predicts that flows in the Amazon could fall this century, while Manabe's team predicts greater rainfall could increase its flow by 23 per cent. And while Manabe foresees a 49 per cent increase in the flow of the Ganges and Brahmaputra rivers that drain the Himalayas, an international study reported that the Ganges would lose flow as the glaciers that feed it melt away.

Global warming has already increased glacier melting by up to 30 per cent. 'After 40 years, most of the glaciers will be wiped out and then we will have severe water problems,' says Syed Iqbal Hasnain of Calicut University, Kerala, reporting the results of a three-year study by British, Indian and Nepalese researchers. The study finds the biggest impact in Pakistan, where the River Indus irrigates half the country's crops. Flows here could double before crashing to less than half current levels by the end of the century. But the declining flows predicted for the Ganges will also throw into disarray a vast Indian government scheme to avoid drought by diverting water from the country's glacier-fed northern rivers to the arid south.

Meanwhile, a team of researchers in France say that climate change is already affecting the world's rivers. David Labat and colleagues at the government's CNRS research agency in Toulouse in France reconstructed the monthly discharges of more than 200 of the world's largest rivers since 1875. They took discharge data held by the Global Runoff Data Centre in Germany and the UNESCO River Discharge Database and used a statistical technique to fill in gaps left by missing data, or changes to run-off caused by dams and irrigation projects.

Their findings reveal that changing temperatures cause river flows to rise and fall after a delay of approximately 15 years, and the team predicts that global flows will increase by about 4 per cent for every 1°C rise in global temperature. However, climate change over the past few decades has already caused discharge from rivers in North and South America and Asia to increase. Run-off in Europe has remained stable, but the flow of water from Africa's rivers has fallen.

Principles of Persuasion

Successful advertising has to keep up with the times

Principles of Persuasion

Successful advertising has to keep up with the times

Principles of Persuasion

Successful advertising has to keep up with the times

Roses are blue, violets are red

If you don't like GM food, try flowers instead

Beautiful flowers, like any other beautiful object, can separate the most sensible of people from their money. On special occasions, people invest in a display of beautiful stems and petals to signal their own feelings or intentions. The result is a cut-flower industry in which roses alone are worth $10 billion a year. But that is nothing, compared with what happened in the past. In 17th-century Holland, tulips (the fashionable flower of the day) grew so expensive that people exchanged their bulbs for houses. One bulb of the most sought-after variety, the flaming red-striped Semper Augustus, sold for twice the yearly income of a rich merchant.

For modern flower growers, the equivalent of the Semper Augustus is the blue rose, which horticulturalists have longed for since the 19th century. Any blue rose sent on Valentine's Day this year will have been dyed. But if Yoshi Tanaka, a researcher at Suntory, a Japanese drinks company, has his way, that will soon change. Dr Tanaka is currently the overseeing the first field trials of a blue rose developed by Suntory's subsidiary, Florigene. If the trials are successful, a dozen blue roses - even if they do look slightly mauve - could, by 2010, be available in florists worldwide.

What Dutch growers of old and Dr Tanaka's employers both grasped is that rarity, and hence economic value, can be created by genetic manipulation.

The stripes of the Semper Augustus were caused by the genes of a virus. Not knowing that an infection was involved, the Dutch growers were puzzled as to why the Semper Augustus would not breed true. The genetics of blue roses too have turned out to be more complicated than expected. The relevant genes cannot easily be pasted into rose DNA because the metabolic pathway for creating blue pigment in a rose consists of more chemical steps than it does in other types of flower. (Florigene has sold bluish genetically modified carnations since 1998.) Success, then, has been a matter of pinning down the genes that allow those extra steps to happen, and then transplanting them to their new host.

Mere colour, however, is for unsophisticated buyers. A truly harmonious gift should smell beautiful as well. Sadly, commercial varieties of cut roses lack fragrance. This is because there is a trade-off between the energy that plants spend on making the complex, volatile chemicals that attract people and insects alike, and that available for making and maintaining pretty coloured petals. So, by artificially selecting big, long-lasting flowers, breeders have all but erased another desirable characteristic.

Smell is tougher to implant than colour because it not only matters whether a plant can make sweet-smelling chemicals, it also matters what it does with them. This was made plain by the first experiment designed to fix the problem. In 2001, Joost cellular waste buckets Lucker, then a researcher at Plant Research International in Wageningen, in the Netherlands, added genes for a new scent into small, colourful flowers called petunias. Chemical analysis showed that the new scent was, indeed, being made, but unfortunately the flowers did not smell any different. As happens in Florigene's blue carnations and roses, Dr Lucker's petunias dumped the foreign chemical they were being forced to create into known as vacuoles. Whereas pigments are able to alter a petal's colour even when they are inside a vacuole, because the cell contents surrounding the vacuole are transparent, smelly molecules must find a route to the sniffer's nose by getting out of the cell and evaporating.

Like Dr Lucker, Natalia Dudareva, of Purdue University, in Indiana, eschews experiments with roses, since these plants have scents composed of 300 to 400 different molecules. She prefers to understand basic odour science using petunias and other similar plants, which have about ten smelly chemicals apiece. She has made an encouraging discovery. By studying the many different pathways through which flowers make their fragrances, she has found consistent patterns in the way these pathways are regulated.

Such co-ordinated patterns suggest that a type of protein called a transcription factor is involved. Transcription factors switch genes on and off in groups. If Dr Dudareva is right, cut roses have lost their fragrances not because the genes that encode their hundreds of scent molecules have each lost their function, but because the plants no longer make a few transcription factors needed to turn the whole system on.

This suggests that the task of replacing lost fragrance is more manageable than it seemed at first. But even when the transcription factors in question have been identified, the problem of the energetic trade-off with pigment production and longevity will remain. So Dr Dudareva is also measuring how quickly the enzymes in scent-production pathways work, in order to identify bottlenecks and thus places where her metabolic- engineering efforts would best be concentrated.

Dr Dudareva's methods may also help to improve the job that flower-scents originally evolved to do - attracting insects that will carry pollen from flower to flower. By modifying the smell of crops such as vanilla, which have specific pollinator species, different insects might be attracted. That could expand the range in which such crops could be grown and thus make some poor framers richer.

Roses are blue, violets are red

If you don't like GM food, try flowers instead

Beautiful flowers, like any other beautiful object, can separate the most sensible of people from their money. On special occasions, people invest in a display of beautiful stems and petals to signal their own feelings or intentions. The result is a cut-flower industry in which roses alone are worth $10 billion a year. But that is nothing, compared with what happened in the past. In 17th-century Holland, tulips (the fashionable flower of the day) grew so expensive that people exchanged their bulbs for houses. One bulb of the most sought-after variety, the flaming red-striped Semper Augustus, sold for twice the yearly income of a rich merchant.

For modern flower growers, the equivalent of the Semper Augustus is the blue rose, which horticulturalists have longed for since the 19th century. Any blue rose sent on Valentine's Day this year will have been dyed. But if Yoshi Tanaka, a researcher at Suntory, a Japanese drinks company, has his way, that will soon change. Dr Tanaka is currently the overseeing the first field trials of a blue rose developed by Suntory's subsidiary, Florigene. If the trials are successful, a dozen blue roses - even if they do look slightly mauve - could, by 2010, be available in florists worldwide.

What Dutch growers of old and Dr Tanaka's employers both grasped is that rarity, and hence economic value, can be created by genetic manipulation.

The stripes of the Semper Augustus were caused by the genes of a virus. Not knowing that an infection was involved, the Dutch growers were puzzled as to why the Semper Augustus would not breed true. The genetics of blue roses too have turned out to be more complicated than expected. The relevant genes cannot easily be pasted into rose DNA because the metabolic pathway for creating blue pigment in a rose consists of more chemical steps than it does in other types of flower. (Florigene has sold bluish genetically modified carnations since 1998.) Success, then, has been a matter of pinning down the genes that allow those extra steps to happen, and then transplanting them to their new host.

Mere colour, however, is for unsophisticated buyers. A truly harmonious gift should smell beautiful as well. Sadly, commercial varieties of cut roses lack fragrance. This is because there is a trade-off between the energy that plants spend on making the complex, volatile chemicals that attract people and insects alike, and that available for making and maintaining pretty coloured petals. So, by artificially selecting big, long-lasting flowers, breeders have all but erased another desirable characteristic.

Smell is tougher to implant than colour because it not only matters whether a plant can make sweet-smelling chemicals, it also matters what it does with them. This was made plain by the first experiment designed to fix the problem. In 2001, Joost cellular waste buckets Lucker, then a researcher at Plant Research International in Wageningen, in the Netherlands, added genes for a new scent into small, colourful flowers called petunias. Chemical analysis showed that the new scent was, indeed, being made, but unfortunately the flowers did not smell any different. As happens in Florigene's blue carnations and roses, Dr Lucker's petunias dumped the foreign chemical they were being forced to create into known as vacuoles. Whereas pigments are able to alter a petal's colour even when they are inside a vacuole, because the cell contents surrounding the vacuole are transparent, smelly molecules must find a route to the sniffer's nose by getting out of the cell and evaporating.

Like Dr Lucker, Natalia Dudareva, of Purdue University, in Indiana, eschews experiments with roses, since these plants have scents composed of 300 to 400 different molecules. She prefers to understand basic odour science using petunias and other similar plants, which have about ten smelly chemicals apiece. She has made an encouraging discovery. By studying the many different pathways through which flowers make their fragrances, she has found consistent patterns in the way these pathways are regulated.

Such co-ordinated patterns suggest that a type of protein called a transcription factor is involved. Transcription factors switch genes on and off in groups. If Dr Dudareva is right, cut roses have lost their fragrances not because the genes that encode their hundreds of scent molecules have each lost their function, but because the plants no longer make a few transcription factors needed to turn the whole system on.

This suggests that the task of replacing lost fragrance is more manageable than it seemed at first. But even when the transcription factors in question have been identified, the problem of the energetic trade-off with pigment production and longevity will remain. So Dr Dudareva is also measuring how quickly the enzymes in scent-production pathways work, in order to identify bottlenecks and thus places where her metabolic- engineering efforts would best be concentrated.

Dr Dudareva's methods may also help to improve the job that flower-scents originally evolved to do - attracting insects that will carry pollen from flower to flower. By modifying the smell of crops such as vanilla, which have specific pollinator species, different insects might be attracted. That could expand the range in which such crops could be grown and thus make some poor framers richer.

Roses are blue, violets are red

If you don't like GM food, try flowers instead

Beautiful flowers, like any other beautiful object, can separate the most sensible of people from their money. On special occasions, people invest in a display of beautiful stems and petals to signal their own feelings or intentions. The result is a cut-flower industry in which roses alone are worth $10 billion a year. But that is nothing, compared with what happened in the past. In 17th-century Holland, tulips (the fashionable flower of the day) grew so expensive that people exchanged their bulbs for houses. One bulb of the most sought-after variety, the flaming red-striped Semper Augustus, sold for twice the yearly income of a rich merchant.

For modern flower growers, the equivalent of the Semper Augustus is the blue rose, which horticulturalists have longed for since the 19th century. Any blue rose sent on Valentine's Day this year will have been dyed. But if Yoshi Tanaka, a researcher at Suntory, a Japanese drinks company, has his way, that will soon change. Dr Tanaka is currently the overseeing the first field trials of a blue rose developed by Suntory's subsidiary, Florigene. If the trials are successful, a dozen blue roses - even if they do look slightly mauve - could, by 2010, be available in florists worldwide.

What Dutch growers of old and Dr Tanaka's employers both grasped is that rarity, and hence economic value, can be created by genetic manipulation.

The stripes of the Semper Augustus were caused by the genes of a virus. Not knowing that an infection was involved, the Dutch growers were puzzled as to why the Semper Augustus would not breed true. The genetics of blue roses too have turned out to be more complicated than expected. The relevant genes cannot easily be pasted into rose DNA because the metabolic pathway for creating blue pigment in a rose consists of more chemical steps than it does in other types of flower. (Florigene has sold bluish genetically modified carnations since 1998.) Success, then, has been a matter of pinning down the genes that allow those extra steps to happen, and then transplanting them to their new host.

Mere colour, however, is for unsophisticated buyers. A truly harmonious gift should smell beautiful as well. Sadly, commercial varieties of cut roses lack fragrance. This is because there is a trade-off between the energy that plants spend on making the complex, volatile chemicals that attract people and insects alike, and that available for making and maintaining pretty coloured petals. So, by artificially selecting big, long-lasting flowers, breeders have all but erased another desirable characteristic.

Smell is tougher to implant than colour because it not only matters whether a plant can make sweet-smelling chemicals, it also matters what it does with them. This was made plain by the first experiment designed to fix the problem. In 2001, Joost cellular waste buckets Lucker, then a researcher at Plant Research International in Wageningen, in the Netherlands, added genes for a new scent into small, colourful flowers called petunias. Chemical analysis showed that the new scent was, indeed, being made, but unfortunately the flowers did not smell any different. As happens in Florigene's blue carnations and roses, Dr Lucker's petunias dumped the foreign chemical they were being forced to create into known as vacuoles. Whereas pigments are able to alter a petal's colour even when they are inside a vacuole, because the cell contents surrounding the vacuole are transparent, smelly molecules must find a route to the sniffer's nose by getting out of the cell and evaporating.

Like Dr Lucker, Natalia Dudareva, of Purdue University, in Indiana, eschews experiments with roses, since these plants have scents composed of 300 to 400 different molecules. She prefers to understand basic odour science using petunias and other similar plants, which have about ten smelly chemicals apiece. She has made an encouraging discovery. By studying the many different pathways through which flowers make their fragrances, she has found consistent patterns in the way these pathways are regulated.

Such co-ordinated patterns suggest that a type of protein called a transcription factor is involved. Transcription factors switch genes on and off in groups. If Dr Dudareva is right, cut roses have lost their fragrances not because the genes that encode their hundreds of scent molecules have each lost their function, but because the plants no longer make a few transcription factors needed to turn the whole system on.

This suggests that the task of replacing lost fragrance is more manageable than it seemed at first. But even when the transcription factors in question have been identified, the problem of the energetic trade-off with pigment production and longevity will remain. So Dr Dudareva is also measuring how quickly the enzymes in scent-production pathways work, in order to identify bottlenecks and thus places where her metabolic- engineering efforts would best be concentrated.

Dr Dudareva's methods may also help to improve the job that flower-scents originally evolved to do - attracting insects that will carry pollen from flower to flower. By modifying the smell of crops such as vanilla, which have specific pollinator species, different insects might be attracted. That could expand the range in which such crops could be grown and thus make some poor framers richer.