BBC News, Brussels
The EU says melting ice is leading to new strategic interests
An EU report says climate change will have a growing impact on global security, multiplying existing threats such as shortages of food and water.
It warns that climate change could cause millions of people to migrate towards Europe as other parts of the world suffer environmental degradation.
States that are "already fragile and conflict prone" could be over-burdened, the report says.
EU proposals to tackle climate change will be discussed by leaders this week.
The stark warning from the report - drawn up by the EU's foreign affairs chief Javier Solana and the European Commission - is that climate change is not just a threat in itself - it is "a threat multiplier".
It says shortages of food and water - even radicalisation and state failure - are likely to get worse if no action is taken.
Africa is likely to be especially at risk, which means migration could intensify, both within Africa itself and towards Europe.
EU External Relations Commissioner Benita Ferrero-Waldner told the BBC: "If the weakest countries cannot adapt, it may lead to, for instance, more forced migration, and even possibly radicalisation and state failure, causing internal and external security risks."
The report also highlights the Arctic as a possible area of future conflict. With the melting of the polar icecaps, new waterways and trade routes are opening up.
The region is rich in untapped oil and gas resources, and last year Russia staked its claim by planting a flag on the seabed beneath the North Pole.
There is, it says, "an increasing need to address the growing debate over territorial claims and access to new trade routes".
But the report does not offer much in the way of specific solutions. It recommends more dialogue, international co-operation and further research.
The EU prides itself on being a world leader on climate change, but turning talk into action is not easy.
On the one hand, the EU scheme for carbon emissions trading is being expanded to take in aviation for the first time.
But plans to limit car emissions and switch to renewable energy are being hampered by objections from industries and some member states, which say they are being unfairly penalised.