There's been a lot of 'noise' recently about how genetically engineered (GE) crops can help "feed the world", and that they can help agriculture in a climate-affected world. But are these promises real or just hype?
If we look at recent studies, they actually highlight the failures of GE technology to deliver on its promises, and the mounting evidence that agricultural productivity is better served by a focus on ecological agriculture . For instance, the latest study (Heinemann et al. 2013) by the University of Canterbury, New Zealand found that "Despite the claims that GE might be needed to feed the world, we found no yield benefit when the United States was compared to West Europe, other economically developed countries of the same latitude which do not grow GE crops". This is not altogether surprising as there simply are no GE crops designed to increase yield. They do not exist.
The majority of currently existing GE crops (for example Monsanto's "Roundup Ready" GE soya) are herbicide tolerant, which allow herbicides to be sprayed liberally, killing all plants apart from the GE crop. This is not good for biodiversity because it affects animals such as birds  and insects  by reducing the abundance of plants that they feed on. This might also include bees, adding pressure to already declining populations. The remainder of GE crops are mostly insect resistant and produce their own pesticide (for example GE Bt corn). These are also not good for biodiversity as these GE crops can kill other insects such as butterflies . Problems of insect resistance  and other, secondary  insect pests, mean that farmers have to continue spraying pesticides with GE Bt crops. With GE crops, farmers are still on the pesticide treadmill.
The reality is that the promised "beneficial" GE crops are stuck at the development stage in the lab. The reason is that scientists are finding that the traits we need to help crops to cope with climate change (e.g. heat tolerance) or increased nutrition (e.g. enhanced vitamins) are actually quite complex and controlled by several genes. Genetic engineering is a crude technology and is no match the tightly controlled network regulating gene expression in cells. For example, 'Golden' rice, a GE rice variety, is still in development after 20 years , largely because of the complexity of the genetic engineering .
Meanwhile, advances in conventional breeding mean that several of the crops promised by genetic engineering are already in farmer's fields. For example, both flood and drought tolerant rice  are already in farmer's fields and drought resistant maize  is available in many parts of Africa where it's needed. Nutrient enhanced crops also exist already – without using genetic engineering  but a more sustainable solution is to improve access to a healthy and diverse diet.
It's clear that GE crops are not capable of producing the crops that farmers and consumers need, whilst the quiet revolution in conventional breeding techniques is already producing these crops .
GE crops are stuck with two simple traits: herbicide tolerance and insect resistance. These do not help to "feed the world", but pose threats to human and animal health, as well as biodiversity.
So the answer to the original question is no. GE crops are not needed to feed the world but are just hype.
Janet Cotter is a Senior Scientist at the Greenpeace International Science Unit.
 Heinemann, JA et al. 2013. Sustainability and innovation in staple crop production in the US Midwest, International Journal of Agricultural Sustainability: DOI:10.1080/14735903.2013.806408;
Jacobsen SE et al.2013. Feeding the world: genetically modified crops versus agricultural biodiversity. Agronomy for Sustainable Development: DOI 10.1007/s13593-013-0138-9
Quist DA et al. 2013. Hungry for Innovation: pathways from GM crops to agroecology. Ch. 19 in: European Environmental Agency (EEA) Late lessons from early warnings: science, precaution, innovation. Vol. 2. EEA Report no 1/2013 pp. 490-517.
 Heard MS et al. 2003a. Weeds in fields with contrasting conventional and genetically modifies herbicide-tolerant crop – I. Effects on abundance and diversity. Philosophical Transactions of The Royal Society London B 358: 1819-1832; Heard MS et al. 2003b. Weeds in fields with contrasting conventional and genetically modified herbicide-tolerant crops. II. Effects on individual species. Philosophical Transactions of The Royal Society London B 358: 1833-1846.
 Pleasants JM & Oberhauser KS 2012. Milkweed loss in agricultural fields because of herbicide use: effect on the monarch butterfly population. Insect Conservation and Diversity doi: 10.1111/j.1752-4598.2012.00196.x
 Dively GP et al. 2004. Effects on monarch Butterfly larvae (Lepidoptera: Danaidae) after continuous exposure to Cry1Ab expressing corn during anthesis. Environmental Entomology 33: 1116-1125.
 Tabashnik B et al. 2013. Insect resistance to Bt crops: lessons from the first billion acres. Nature Biotechnology 31: 510-521.
 Catangui MA & Berg RK 2006.Western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera : Noctuidae), as a potential pest of transgenic Cry1Ab Bacillus thuringiensis corn hybrids in South Dakota Environmental Entomology 35 1439-1452.
 Greenpeace 2012. Golden Illusion. http://www.greenpeace.org/international/Global/international/briefings/agriculture/2012/GoldenRice/GoldenIllusion.pdf
 Greenpeace 2009. Smart Breeding. Marker-Assisted Selection: a non-invasive biotechnology alternative to genetic engineering of plant varieties. http://www.greenpeace.org/international/Global/international/planet-2/report/2009/11/smart-breeding.pdf