(CNN) The crisis in northern Syria is only getting worse.

Hundreds of thousands of people are trying to escape the fighting as colder weather sets in. Syria is already facing the largest displacement crisis in the world, according to the United Nations.

More than a dozen aid agencies have signed a joint letter to UN Security Council members reminding them of the importance of protecting civilians and allowing their humanitarian efforts to continue.

While some charities have announced plans to pull out of Syria -- others are still there helping people in displacement camps.

You can help several nonprofits on the ground in these camps who are providing refugees with shelter, healthcare, water, food and hygiene services by going here or clicking on the button above.

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