Since 1994 Ms Higuero has worked at UNEP in the areas of natural resource economics and policy, environmental law, negotiations of multilateral environmental agreements, governance, intergovernmental processes and natural resource management, at the global, regional and country levels with governmental and non-governmental stakeholders.
As focal point for biodiversity-related conventions and regional seas programmes at UNEP headquarters from 1998 to 2002, Ms. Higuero was actively involved in the policy and programming of activities to support implementation of biodiversity related Conventions. Further, Ms Higuero was seconded from UNEP for the negotiations of the Cartagena Protocol of the Convention on Biological Diversity, the Regional Seas Convention for the Northeast Pacific, and the CMS Memorandum of Understanding on Marine Turtles. When she was promoted in 2002 to coordinator for the Pan European Biological and Landscape Diversity Strategy (PEBLDS), an intergovernmental process focusing on biodiversity, she moved to the UNEP-Regional Office for Europe in Geneva. Her main task was to provide secretariat services to the Chair of the PEBLDS, its Council and Bureau, as well as write background papers, make presentations and facilitate and chair meetings and conferences. The core of the work required her to engage with governmental and non governmental organizations on the implementation of activities for the conservation and sustainable use of biodiversity in the pan European region. She has taken part in the Environment for Europe (EfE) process since 2002, setting priorities and planning strategic actions for the pan European region for approval of the Ministers at the EfE Ministerial conferences every 4 to 5 years.
In 2009, Ms Higuero became the overall programme coordinator for the UNEP Regional Office for Europe and has contributed significantly to the development of UNEP’s Programme of Work by linking UNEP's strategy to the goals of the Regional Office for Europe. She supervises and guides the regional sub-programme coordinators for Europe. As coordinator of the ecosystems management sub-programme, she has been most recently involved in the negotiations of a pan European legally binding agreement on forests, developing capacity-building materials on sustainable agriculture for small farmers in Eastern Europe; Arctic policy and project development; national work on the Economics of Ecosystem and Biodiversity; valuing natural capital and green economy issues etc.