The rising cost of food is an issue affecting people all over the world and is one of the key issues on the table as ministers gather at the Rio+20 conference on climate change.
In the UK the average family food bills rose by more than 26% between 2007 and 2011 and although there has been some easing in the inflation figures from this year, many families are noticing the increased costs of their weekly shop.
Food price rises are caused by several factors, according to the Food and Agriculture Organisation of the United Nations (FAO):
Supply problems: flooding and environmental factors affect crop production
A global rise in living standards leading to a greater demand for meat
Livestock consumes more grain, and takes up increasingly precious farmland space to grow crops
Between 2007 and 2008 the cost of basic foods food prices rose by up to 80%.
The price of wheat shot up by 90% and the price of maize shot up by 80%, only to fall rapidly again in the second half of 2008, and only to spike again in 2011, and into 2012.
Increasing food prices hit vulnerable, 'food insecure' countries the hardest: after 2008 millions of people in sub-Saharan Africa and parts of South East Asia where pushed into extreme poverty and hunger. Farmers are particularly vulnerable as volatile markets make it increasingly difficult for them to plan.
Experts from the FAO and campaigners are increasingly recognising the role of financial speculation as a key factor in food price rises.
Since food markets were liberalised more than 12 years ago there has been an influx of purely financial players who have no interest in actually buying food, but trade and profit from changes in food prices.
In 2003 this market was worth £3 billion, in 2008 it was worth more than £55 billion. Olivier De Schutter, the United Nations Special Rapporteur on the Right to Food explains:
Banks including Goldman Sachs and Barclays have created funds that allow investors to speculate on the price of key food crops. It has generated huge profits for those involved, campaigners say Goldman Sachs is estimated to have made more than $1 billion in 2009 alone and Barclays as much as £340 million a year from trading food commodities. Barclays Capital says:
The UN is calling for greater regulation to prevent excessive speculation driving up food prices artificially.
Europe is due to pass legislation to apply limits to the type of speculation that can occur in food crops and campaigners are hoping that the final resolutions agreed at Rio+20 will include plans to curb this type of market activity. Heidi Chow from the World Development Movement told ITV New urgent action is needed.