(For more G8 summit stories, click on [G7/G8]) (Adds food statement, Japanese official comments)

* G8 says world must act on climate change through UN

* G8 sees downside economic risks, serious financial strains

* Record oil prices, high food prices need to be tackled

* Africa aid commitments confirmed

By Tabassum Zakaria and David Clarke

TOYAKO, Japan, July 8 (Reuters) - G8 nations, papering over deep differences, said on Tuesday they would work toward a target of at least halving global greenhouse gas emissions by 2050 but emphasised they would not be able to do it alone.

In a communique released during a summit in northern Japan, the Group of Eight leaders also agreed that they would need to set interim goals on the way to a "shared vision" for 2050 although they gave no numerical targets.

Mention of mid-term goals was an advance from last year when the G8 agreed at Heiligendamnn, Germany, only to "seriously consider" a goal of halving emissions by mid-century.