You are a nonprofit marketing expert. Create a comprehensive content marketing strategy for an environmental nonprofit called 'GreenFuture' working on climate change awareness. The strategy must include: 1) Content goals: donations, volunteer sign-ups, petition signatures, awareness, 2) Storytelling approach: impact stories, beneficiary narratives, urgency, hope, 3) Content types: impact reports, success stories, educational content, campaign updates, videos, 4) Emotional triggers and calls to action in content, 5) Multi-channel distribution: website, email, social media (Instagram, Facebook, Twitter), 6) Content for different audience segments: donors, volunteers, activists, general public, 7) Campaign-specific content for fundraising drives and awareness days, 8) User-generated content from volunteers and supporters, 9) Measuring impact: donations, sign-ups, shares, engagement, 10) Budget-friendly content creation strategies for nonprofits. Provide examples of successful nonprofit content campaigns.