How science aims to feed seven billion peopleas birth announcements go, it was a pretty big one. Sometime around the end of October last year, the world's population officially reached seven billion people. Seemingly, it is the kind of celebration we should get used to. By 2050, an extraordinary nine billion people are expected to call Earth home. But these are milestones we cannot yet afford to celebrate, because as the population swells, our ability to feed everyone diminishes. Globally, one billion people are undernourished at present, especially in Sub-saharan africa and Asia. By around 2050 the swelling global population and affluence is expected to increase demand for food production by 70, %with a 100%increase expected in some developing countries. Yet most of the globe's best farmland is planted already or grazed. And when you factor in climate change, limited fresh water supplies and competition for harvests from biofuel makers, it is clear the world faces a major challenge. One note of reassurance is that we have been in a similar fix before, and our ingenuity proved to be up to the challenge. In the mid-20th century, when the global demand for food outpaced supply and famine was routine in places such as India and Pakistan, what helped save the day was the so-called"Green revolution Â. The movement was spearheaded by American agronomist Norman Borlaug, who cleverly bred wheat to be shorter but sturdier and better at producing the parts we eat. Borlaug's approach drew its fair share of critics, in part through its reliance on pesticides and fertilisers. But breeding high-yield crops in this manner more than doubled farm field yields globally in 50 years, particularly in Latin america and Asia, and helped to avert mass famines-an achievement that earned Borlaug the 1970 Nobel Peace Prize. Recently however, the trend toward higher yields has flattened, and the world finds itself in need of another revolution. This time, however, there is no obvious blueprint. Green revolution 2. 0 is possible, scientists say, but it will be engineered using tools that were unavailable to Borlaug and others in their pioneering days. Instead of relying on traditional breeding techniques and the lavish use of chemicals, the machinery sowing this new revolution includes supercomputers, molecular biology and arrays of sensors. Here, BBC Future profiles four areas of research to discover how close they are to feeding the coming nine billion. Squeezing more from the sunin a corner of Illinois they are trying to improve on billions of years of evolution. A group led by British-born plant scientist Stephen Long is trying to improve the ability of plants to harness energy from the sun. Their aim is to turbocharge photosynthesis, the fundamental process that allows plants to use the light they capture to convert carbon dioxide into organic necessities like sugar and starch-or food, as we like to call it. According to Long, plants currently operate at about one third of their potential efficiency when it comes to photosynthesis, which hints that if you can find a way to ramp it up, you can also produce more food. In 2006, Long and his colleagues described how climate-change experiments have shown that rising atmospheric levels of carbon dioxide lead to higher rates of photosynthesis in plants. When this happens, yields can improve by 15%in vital crops like wheat, rice and soybean. Increasing atmospheric carbon dioxide further is hardly a practical or desirable way to boost crops, so the team set about looking for the genetic switches that could mimic the action and ramp up the plant's ability to harness the sun. That is easier said than done. More than 100 different proteins play a role in photosynthesis interacting in countless different permutations, Long says. Trying to work out which ones could boost photosynthesis through trial and error would take years. But there is a shortcut: supercomputers. Long's team broke photosynthesis down into a long series of mathematical equations and fed them to the National Center for Supercomputer Applications in Illinois. The supercomputer whirred through the numbers and spat out a list of"best-bet  interventions. For example, one potentially easy win they identified was to dial up production of just a single protein known as sedoheptulose bisphosphatase, or SBPASE. British researchers have shown already that tobacco plants engineered to express more SBPASE grew 10%larger in a glasshouse. And if it works in them, Long says, then it is likely to work in any crop, since photosynthesis does not vary much among plants. However, this is not the only way of increasing photosynthesis. Scientists are also exploring the idea that genes from the ancestors of modern-day plants might boost the ability of crops to harness the sun. It is well known that primitive plants known as cyanobacteria have a talent for concentrating CO2 within their cells at levels that make photosynthesis more efficient. It is believed that plants lost this ability when they transferred to the land 500 million years ago, because they did need not it. Researchers at the Hebrew University of Jerusalem have evidence that this may be one key to increased yields. In trials they achieved a 20%increase in tobacco plants after adding a single cyanobacteria gene called inorganic carbon transporter B (Ictb. Long says that he and colleagues from the University of Nebraska have carried out some initial tests on soybeans transformed with the same gene, and have recorded a 10%increase in yield. However, there is a long way to go before either of these techniques can be used in the field. There is huge opposition to genetically modified crops in many countries, with some groups citing safety concerns and others ethical, arguing that the developing world should not be used as a laboratory to test such crops. But even if these arguments are won and efforts to re-engineer photosynthesis succeed, Long admits it would take at least a decade to move these transformed plants from research settings to farm fields. It would also take a lot of money.""The cost of meeting global regulatory requirements for a single gene engineered into a crop can run into many millions,  says Long.""While we can show ways of achieving this, actually getting this to farmers could be more difficult.  Turning the world greentraditionally, farmers have sought out the best places to plant their crops oe nutrient rich flood plains and the sides of volcanoes. But we have reached a point where all of this high quality land is taken. Instead, farmers are forced to use ever more marginal land oe plots that are too wet, too dry, too short on vital nutrients, or are laced with damaging aluminium or salt. As a result, there is a push to develop crops that not only grow in these conditions oe they relish them. For example researchers like Abdelbagi Ismail at the International Rice Research Institute (IRRI) in the Philippines are developing strains of rice that can flourish in flooded areas. This is an important problem to tackle. As many as 20 million hectares of cultivated rice are affected by submergence in Asia every year. To get round the problem, Ismail and his team scoured the vaults of their institute's rice seed bank oe the world's largest with more than 110,000 varieties. They were looking for types of rice that survive on sketchy land, regardless of whether they produced low or high yields. In one case they found a strain that did not waste precious energy trying to elongate itself above the waters when submerged by a flash flood, and instead put itself into a sort of temporary slumber. Using genetic techniques unavailable to Borlaug, they then crossed this flood-tolerant strain with a high-yield strain of rice.""This form of breeding used to take 6-15 years,  says Ismail.""Now we can have a tolerant variety in only 2-3 years.  And it seems to work. Tests have shown that fields planted with the hybrid that experienced flooding show average yield gains of close to one ton per hectare, says Ismail. Their submergence-resistant rice has been distributed to farmers in India, Bangladesh, Nepal, Indonesia and the Philippines. IRRI hopes it will reach 5 million farmers in Asia and Africa by 2014 and 20 million farmers by 2017. Vitamin shakeincreasing the amount of food we produce is one thing. Producing nutritious food is another according to Yassir Islam, spokesperson for Harvestplus, a nonprofit organisation looking to improve nutrient content in staple foods. He says the next green revolution will have to be accompanied by a rethink about how nutritious the food is that we put on the table of millions of people every day. Too many people in Asia and Africa already suffer from what Harvestplus calls"hidden hunger Â, or deficiencies in key micronutrients. These people live in parts of the world where their diets are dominated by staples oe foods such as rice, wheat, cassava, millet and maize oe that are high in calories but lack iron, zinc, Vitamin a and other micronutrients. Deficiencies can reduce IQ, lower disease resistance, stunt growth and even cause blindness, which greatly increases a person's risk of death in the developing world. The best-known example of boosting nutrition in staple crops is golden rice, which has been engineered with genes from daffodils and bacteria to produce beta-carotene, a nutrient that the body can convert into Vitamin a. Developed in the 1990s, and field tested in the 2000s, golden rice is still not available for general use. Some environmental groups, including Greenpeace, fear that this genetically modified strain could contaminate and harm other vital rice strains. But rather than importing genes from another organism researchers are now trying to find maize strains that naturally produce high levels of beta-carotene. Torbert Rocheford of Purdue University, Edward Buckler of Cornell University, and their collaborators screened around 300 maize strains, and unearthed some with boosted beta-carotene levels. They then looked for any genes in these maize strains that resembled genes linked to high beta-carotene levels in other plants.""It's the sort of process where either you hit a grand slam home run or strike out. There's nothing in between,  says Rocheford. They scored, finding a small number of maize varieties that grow in both tropical and temperate climates and which carry a gene variant that slows down the conversion of beta-carotene to other substances, leaving more to make Vitamin a. As important, they also found a genetic marker that signals when this sought-after gene variant is in place. Plant breeders are using the naturally occurring maize plants and those markers to breed new plants. So far the process has boosted concentration of beta-carotene in the corn from practically nothing to about 8 micrograms per gram oe around 53%of Harvestplus'target for the micronutrient. The organisation expects to release corn that achieves that target in 3-4 years. What will really determine its success is if farmers will regularly plant this orange corn in a region where people traditionally eat white corn with no beta-carotene. This year, Harvestplus, which like the IRRI is funded by the Bill and Melinda Gates Foundation, is releasing the fortified corn in Zambia, where more than half of children experience Vitamin a deficiencies. The plan is to eventually adapt the plants to fields elsewhere in Africa in Latin america and in Asia. Plant smartevery one of us likes to be treated as an individual. And it is no different for fields, say advocates of an expanding type of agriculture called precision farming. This is based on research that shows there is a significant variation in how crops grow over distances as small as an acre, says Raj Khosla, an agriculture researcher at Colorado State university, and president of the International Society of Precision Agriculture. He is helping farmers to harvest a new crop: data. They do it by bringing electronic tools into their crop rows-global positioning systems, infrared devices that measure soil's electrical conductivity and light and sound sensors. Combining all that and more gives farmers precise information about variety in plant health, size and even nitrogen needs. The idea is that by collating all of this, farmers can produce highly detailed maps of their fields so that they can identify how much seed, fertilizer, water, herbicides and pesticides different areas require. At first the appeal was that farmers would save money and avoid environmental harm by not adding unnecessary fertiliser or water, Khosla says.""But with precise input management, farmers can also influence grain yield and efficiency.  Some academics and sustainable farming advocates see this type of farming as one more push toward industrialising food production and making more farmers dependent on agribusiness. But Josã  Molin, a precision farming researcher at the University of Sao paulo in Brazil, says the concept has promise for farmers with and without the means or inclination to buy expensive equipment.""We still have to develop the concept to apply it to small farmers and to low tech or low income areas,  says Molin.""But the concept is always the same. Even small fields are different in different locations. We should treat them differently.  Given the imperative to expand the world's food supply, farmers need as much help as they can get even down to the acre, says Khosla.""Previously we just raised food for humans and animals. In 2011 more corn went to biofuel than to feed for the first time in the US. Another big pressure is climate change. A third is the lack of water.  Khosla says.""We're working under tremendous pressures today compared to those in the first green revolution. We can't just continue to do things the way we have done them.  If you would like to comment on this story or anything else you have seen on Future, head over to our Facebook page or message us on Twitter

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