The G8 summit of industrialised nations opens in Toyako on the Japanese island of Hokkaido on Monday. Here, BBC correspondents preview the issues likely to dominate the talks.
Click on links below to read their views:
Tough times ahead
By Economics Correspondent Andrew Walker
When these summits were first conceived by a smaller group of countries in the 1970s, the world economy was the main focus. In the intervening years, the agenda has become much wider, but this time economic troubles have forced their way back to centre stage.
There are some similarities with those grim days - although it's important not to exaggerate the parallels. Back then, there was an oil crisis, rising inflation and weak economic growth, or at times, none.
Rising oil prices are a global concern
Today those concerns are back. Energy and food prices have pushed inflation up. The international credit crisis has weakened economic growth, though in most economies it has not been extinguished, so far at least. The latest spike in oil prices could aggravate both problems. It adds to inflation, hits company profits and leaves consumers with less to spend on other things.
What can the G8 do about the oil price? Probably not very much. The British Prime Minister Gordon Brown has some ideas about reducing the world's dependence on oil. They might help in time, but not in the next couple of years.
On inflation, central banks are in charge. The European Central Bank has already made a start by raising interest rates in the last week. Others have hinted they may follow. It is not the best time to be doing it. Slowing economic growth normally calls for lower interest rates. The US Federal Reserve has cut rates, but it looks like its next move will be an increase.
The G8 leaders will wrestle with all these problems and no doubt come up with some ideas. But ultimately they - and we - will probably just have to hold tight for an uncomfortable ride.
Rising food prices
By international development correspondent David Loyn
The food price crisis has narrowed to one specific request to the G8 - funding for an ambitious aid programme to boost agriculture in the world's poorest nations so that they can feed themselves.
The G8: Britain, US, Germany, France, Canada, Japan, Italy, Russia
It is the first time for many decades that agricultural investment has taken centre stage in this way, and the presence of leaders of the largest economies in Africa and Asia at the margins of the summit will help to focus attention on the issue.
Beyond the aid demand the food price issue will also tie in with the big economic concern that is central to the deliberations - tackling soaring oil prices.
The price of oil is the main cause of volatility in food prices.
This summit is unlikely to discuss other causes, in particular the role of biofuels, denied by the US despite increasing evidence that the rush to plant crops for fuel has been a major contributory factor in the high cost of food.
The summit is likely to try to provide political impetus towards breaking the logjam in world trade talks.
A round of negotiations to provide a new regime of trade rules was launched in Doha in 2001 - designed to be a "round for the poor".
Success should make it easier for poor nations to export agricultural products, while opening up China and India to increased trade.
Success in this could have more impact than an aid package in enabling development in some of the poorest countries in the world.
But protectionist pressures tend to rise during hard times, and at the time of the highest rise in food prices - at the start of the year - major exporting countries imposed export restrictions.
The G8 will be asked to oppose these moves.
Africa's broken promises
By BBC World Service Africa editor Martin Plaut
Both the leaders of the industrialised world - the G8 - and the presidents of Africa are failing to keep the promises they made at Gleneagles summit in Scotland in 2005.
The deal made there was simple:
- The G8 promised to double aid by 2010, increasing aid to Africa by $25bn (£12.5bn)
- Africa promised to end the cycle of coups, crises and corruption that have blighted the continent
Neither have kept their word.
Although there has been substantial progress on cancelling Africa's debt, progress on aid has fallen behind schedule.
According to aid campaigners, the G8 has increased aid to Africa by only about a quarter of the $25bn promised.
Worse still, according to a draft communique obtained by the UK's Financial Times newspaper, the G8 leaders plan to commit themselves to fulfilling "our commitments on [development aid] made at Gleneagles" - at their meeting in Japan, but will fail to cite the target of $25bn annually by 2010.
Expressing her concern, the head of Oxfam, Barbara Stocking said: "We cannot allow G8 leaders to view current global crises as an excuse to lower ambitions and push back on the poverty agenda."
But Africa has also failed. Since 2005 only one country has become truly democratic, according to the Africa Panel, established after Gleneagles.
There are also continuing conflicts in Somalia, Niger and the Democratic Republic of Congo, and border crises between Chad and Sudan, Eritrea and Djibouti.
At last week's Africa Union summit in Egypt, the continent's heads of state failed to impose any sanctions against the government of Zimbabwean President Robert Mugabe, despite its own monitors declaring that the recent elections failed to meet democratic standards.
By Environment Correspondent Richard Black
A few months ago, it looked as though climate change would head the list of major G8 issues. But concerns over food and energy supplies have taken away its top billing.
Climate and energy concerns may push the G8 down an efficient track
Discussions will proceed, however - between G8 members themselves, and also between governments invited as guests of the "major economies" or "big emitters" group, including China and India, the developing world's most significant carbon dioxide producers.
The battle lines are rather familiar. The EU has already pledged to cut emissions by 20% from 1990 levels by 2020, Japan has promised to reduce emissions by 60-80% by 2050 and to consider shorter-term targets, the US has said it will consider a 2050 goal.
The US, with some backing from Japanese and European leaders, insists that major developing countries would have to take on some kind of commitment too - a position that is rejected by India and other developing countries.
What just about everyone agrees on is that the UN climate convention should remain the sovereign body for a future global deal. The idea is to secure the deal by the end of 2009, so it can come into force when the current Kyoto Protocol targets expire.
The G8's role, then, cannot be to agree a global deal. What it can do is act as a place where leaders of politically more muscular countries can agree the parameters they are happy with and the places they are not prepared to go.
And what of the other environmental issues that the UN identified in its landmark Global Environmental Outlook (GEO-4) report last year as requiring urgent attention?
Only one is likely to get a look-in at all, and that is the rapid degradation of the natural world's resources, species and ecosystems.
In May, G8 environment ministers agreed a Call to Action for Biodiversity.
Measures include stepping up monitoring of biodiversity loss, encouraging corporate social responsibility, promoting sustainable forest management and looking towards a future global target for when the existing one - to halt the global loss of biodiversity by 2010 - is missed, as it surely will be.
By Diplomatic Correspondent James Robbins
Although this Summit is dominated by crises in the world economy and the threat from climate change, leaders also have to confront a range of other challenges. The most prominent are:
The leaders are expected to repeat a call from G8 foreign ministers urging North Korea to "fully cooperate" in the verification of its nuclear declaration and settle the issue of the country's past abductions of Japanese nationals. That remains a major concern of Japan.
This summit is also expected to call on North Korea to "abandon all nuclear weapons and existing nuclear programmes as well as ballistic missile programmes."
The White House says it believes leaders will "strongly condemn" the Zimbabwe government of President Robert Mugabe in their official communiqué.
"I think the G8 will strongly condemn what Mugabe has done,"
Dennis Wilder, the National Security Council's senior director for Asia told reporters aboard Air Force One as President George W. Bush was on his way to Japan.
"It will strongly condemn the legitimacy of his government and his governing of Zimbabwe."
But questions remain over Russia's willingness to agree to strong criticism, fearing that it could make it harder to resist UN sanctions.
A powerful statement on Zimbabwe is regarded as vital by Britain's Prime Minister, Gordon Brown, who has taken a leading role alongside the US in condemning the brutal violence of President Mugabe's regime to cling to power after recent elections.