Europe is a hot-spot for aquatic introductions with nearly 900 alien species reported at present. Introduction of Invasive Alien Species (IAS) is regarded as a serious threat to European biodiversity and ecosystems. Introduced seaweeds represent one of the largest groups of marine aliens in Europe, and are reported to constitute between 20 and 29 % of all alien marine species. Seaweeds are major primary producers in coastal areas, and are extremely important for coastal ecosystems by supporting high biodiversity through structuring complex habitats for associated species. Large-scale substitution of dominant native seaweeds with alien species will consequently alter coastal productivity and food web structure, and therefore impact ecosystem services. Only a few impact studies on invasive seaweeds have been carried out worldwide, and these have detected a range of negative ecological effects, with reduction in abundance of native biota being most frequently reported. Little is known about how temperature variation influences the relationships between alien and native seaweeds. Facing climate change, species can either move, change their phenotypes to match with the new environment, or adapt through genetic changes to the new conditions. The aim of the INVASIVES project has been to assess present and future impacts of invasive alien seaweeds on the North-Atlantic coastal biodiversity. The project has specifically aimed at predicting the effects of alien seaweeds under climate variability and rising sea surface temperatures in the North-Atlantic. The following main objectives have been addressed: 1) To assess the importance of new pathways of alien seaweeds to European coasts, 2) To develop niche models which predict the potential range of alien seaweeds, under present and future climatic conditions, 3) To investigate the ecological processes responsible for substituting native seaweeds with invasive ones, 4) To assess the impact of alien seaweeds on native seaweed-associated fauna and food webs, 5) To study how acclimation and adaptation processes can influence the success of invasive seaweeds, and 6) To study how climatic variation affects the biochemical acclimation of invasive seaweeds. By using a combination of modeling, field studies, ecological experiments, biochemical and molecular work, the impact of alien seaweeds on the native biodiversity under variable climatic conditions has been studied. The project consortium has comprised seven partners from five countries (Iceland, Norway, Belgium, France and Portugal), and experiments and fieldwork have been carried out in northern, western and southern Europe. Three large consortium project meetings have been arranged during the project period, the upstart meeting was held in Belgium (Gent) in 2013, the halfway meeting in Norway (Bergen) in 2014, and the final meeting in Portugal (Faro) in 2016. These meetings were particularly useful for planning cooperative or complementary studies, and for carrying out an integrative work by sharing and discussing the results. A project web page was launched during 2014, where news and results from the INVASIVES project have been made available, as well as news about invasive species in general (https://invasives.b.uib.no/). The project has produced results within a wide range of areas, covering all the main objectives of the project, and represent main contributions to understanding how invasive alien seaweeds (IAS) spread, adjust, and impact seaweed communities in Europe under changing climate conditions. Results from the project have been presented at several symposia and seminars, and so far a total of 17 papers or book-chapters have been published or are accepted for publishing.