Major issues in forest science, such as climate change, bio-energy, biodiversity, and water, were assessed by IUFRO responsive to the broader scientific and policy communities to tackle more complex global environmental, social, and economic issues impacting forests. Other issues highlighted in this paper are forest health and forest genetics; forest modeling and operations engineering; challenges for mitigation and adaptation; public participation on decisions, research, and distribution of benefits; estimating ecosystem services, biofuels and biodiversity; societal issues, including health, food, poverty, urbanization, and lifestyle; educational change in structure and topics; and information and research administration. As forest science faced various challenges in the last few years, there is a need for interdisciplinary approaches and cross-sectoral collaboration. These interrelated and emerging key-issues, particularly climate change, biodiversity, bio-energy and water, are of strong interest to policy makers and groups inside and outside the forest sector. These will all be of high relevance to forest science and to IUFRO in the coming years, primarily for global collaboration.