This document is a collection of the abstracts from ENVIRON 2020, the annual Environmental Researchers Colloquium hosted by the Dublin City University Water Institute in conjunction with the Environmental Sciences Association of Ireland. The ENVIRON colloquium is the largest gathering of environmental researchers in Ireland with almost 300 delegates attending this year. This event was an opportunity for environmental researchers both new and experienced to share their research with an audience drawn from academia, government bodies, industries, the community and general public. In recognition of the United Nations Intergovernmental Panel on Climate Change report and the publication of Irelands climate action plan which declared a Climate and Biodiversity Emergency, this year’s colloquium overarching theme of “Ireland’s Water, Energy & Environment in a Climate and Biodiversity Emergency” aimed to focus on what key researchers in Ireland are doing to tackle this emergency, while also stimulating important discussions and actions to address this emergency. The colloquium was formally opened on Tuesday 20th October by Professor Daire Keogh (President, Dublin City University), Professor Fiona Regan (Water Institute, DCU), and Dr Liam McCarton (ESAI Chairperson) followed by a Keynote Address by Gilles Gantalet from DG Environment. Three concurrent sessions followed over the course of the next three days, at which over seventy papers and 80 posters were presented under the following thematic areas: Biodiversity and Ecosystems Water Quality and Resources, Climate Change, Marine and Coastal, Waste Management, Energy, Wastewater and Water Reuse, Environmental Policy and Communication, Sustainable Infrastructure & The Built Environment, Urban Development & Air Quality, Human Health, Ecotoxicology, Sustainable Land Use and Agriculture and Technology and the Environment. These parallel sessions were interspersed with 6 poster sessions, a panel discussion on Wednesday at 12pm and a workshop on Thursday morning to stimulate discussion on the United Nations Sustainability Goals. A unique feature of this year’s event is that it was the first time Environ was delivered totally online, using a conference app, WHOVA, with speakers, poster presenters and plenary sessions all happening virtually. We have also introduced a conference app, WHOVA (whova.com) which we hope helped people network online in our virtual coffee breaks as well as having direct access to abstracts and presentations online.