The United Nations has warned of a "silent tsunami" caused by more expensive food that could affect 100 million people. Aid groups are concerned that restricting exports could worsen the situation. Prime Minister Gordon Brown has stated that Britain will push for changes to EU biofuels targets if it is proven that growing crops for fuel is driving up food prices. The World Food Programme has also expressed alarm, with its director warning that a large number of people are at risk of hunger due to the current crisis. Factors contributing to the food price increase include higher fuel costs, adverse weather conditions, increased demand due to rising incomes, and the use of land for biofuel production. The price of rice from Thailand, the leading exporter in the world, has more than doubled this year. Several major food exporting countries, including Indonesia, Kazakhstan, Egypt, and Cambodia, have implemented restrictions on food exports to ensure their own supplies. According to Sheeran, the issue is worsened by artificially created shortages, as the world has been consuming more than it has been producing for the past three years, resulting in reduced stocks. Rising prices have caused the World Food Programme to face a shortage of funds to purchase food for its programs, leading to cutbacks in school feeding initiatives in Tajikistan, Kenya, and Cambodia. The WFP, which initially estimated it would need $2.9 billion in 2008 to meet its needs, now anticipates having to raise that amount by a quarter due to the significant price increases in staple foods like wheat, maize, and rice. Britain promised $900 million to assist the WFP in addressing immediate issues, while Brown expressed concerns about using crops for fuel. He stated that if the UK review determines a need for change, they will advocate for adjustments to EU biofuels targets. Japanese Agriculture Minister Wakabayashi proposed that the WTO establish clear guidelines for food export restrictions imposed by producer nations. The Asian Development Bank's Rajat Nag declared that the era of inexpensive food is finished and encouraged Asian governments to avoid distorting markets with export limitations, but instead utilize fiscal measures to aid the less fortunate. U.N. Secretary-General Ban Ki-moon warned that rising food prices could reverse progress in reducing poverty. Former Secretary-General Kofi Annan also suggested that climate change is worsening the global food crisis, potentially leading to severe hunger in many poor countries. He emphasized that the poorest populations are disproportionately affected by climate change, despite contributing the least to it. Annan called for those responsible for pollution to take responsibility, as climate change poses a significant threat to various aspects of society including health, security, political stability, and social unity.