To the residents of Arctic communities, sea ice is an integral part of their lives that dictates what they hunt, where they travel and by what means. As a habitat sea ice hosts species that provide clothing and construction materials and make up a large part of the subsistence diet of Inuit. As a stable platform it provides often the only access to other communities and hunting grounds. Conversely, when thin or broken, sea ice can hinder or inhibit travel by either sled or boat. To thrive in such an environment requires a profound understanding of sea ice and great skill in observing its patterns of behaviour. As a result Arctic communities possess a wealth of knowledge about the sea-ice environment developed over many generations of learning how to hunt and travel on it safely and effectively. By contrast, the scientific community has historically considered sea ice as an obstacle to travel through rather than a platform to travel on. This is reflected by the terminology adopted by the World Meteorological Organization (WMO, 1973), which categorizes sea ice largely according to its impact on marine navigation. However, in more recent years sea ice has come to be recognized as a crucial part of the global climate and ecosystems. The ice-albedo feedback process, whereby the retreat of sea ice enhances ocean warming and leads to further retreat, is now well known and the extent of sea ice is closely watched as a critical indicator of the state of the climate. Recently, the ecological significance of sea ice was marked by the listing of the polar bear as an endangered species in the USA due to habitat loss caused by the retreat of Arctic sea ice. However, the importance of sea ice to Arctic communities is not so well known outside of Arctic communities. If Arctic sea ice were to disappear completely in summer its loss would be felt across the globe, but first and most keenly by those living on its shores. The residents of Arctic communities are therefore well-positioned to observe ongoing changes at the local level. By working with Arctic residents in their communities, not only can we tap into a vast wealth of sea-ice knowledge pre-dating any instrument record, but we can also make sure that the science is relevant to their needs. In this talk I will describe the dynamic relationship between humans and sea ice in the Arctic and present results from community-based sea-ice observatories that are on the front line of a rapidly changing environment.