UNITED NATIONS - UN Secretary-General Ban Ki-moon on Thursday called on developed countries to take concrete measures to tackle the challenges of food crisis, climate change and development. Ban made the appeal on the eve of a three-nation tour that will be followed by his participation in next month's Group of Eight (G8) summit in Japan. "If ever there were a time to act, together as one, it is now," Ban told journalists at the UN Headquarters. "Seldom has the global community been under such stress. The ties that bind us, as humankind, are fraying. We must work especially hard to preserve them, at this critical juncture, in the interests of our common future," he said. The G8 countries are: the United States, Canada, Britain, France, Germany, Italy, Japan and Russia. Ban said it was "no exaggeration to say that we face three crises, all interrelated and demanding our immediate action," with the problems caused by soaring food prices the most pressing. At the G8 summit in Hokkaido, Japan, from 7 to 9 July, the secretary-general said he would appeal to world leaders to deliver on the measures they agreed to under a road map drawn up at a major international meeting in Rome earlier this month. "It calls on nations to remove export restrictions and levies on food commodities and reduce agricultural subsidies, particularly in developed countries," he said, adding that the proportion of official development assistance (ODA) for agricultural production and rural development should be trebled. Climate change is no less immediate a concern, Ban said, urging world leaders to press forward from the achievements of last year's conference in Bali to devise a lasting agreement on greenhouse gas emissions by next year. "In Hokkaido, I will ask for short- and medium-term targets for reducing greenhouse gases. It is not enough to talk of change by 2050. If we want real change, we must begin now - with targets for real progress by 2020," he said. A fully funded and operational adaptation fund, to help the world's most vulnerable nations cope with climate change, must be in place by the end of this year, according to Ban, who also called for concrete steps to transfer the latest low-carbon technologies to poor states. The secretary-general said that climate change and the global food crisis are slowing and in some cases reversing the progress made towards the anti-poverty targets known as the Millennium Development Goals (MDGs), which world leaders have agreed to strive to achieve by 2015. "In Hokkaido we must deliver on our commitments. I will also seek increased funding for specific programs relating to infant and maternal health, community health projects and disease control- HIV/AIDS, malaria, tuberculosis and neglected tropical diseases."