The analysis projections, in which two Portuguese researchers participated, "show that, by the middle of the 21st century, climate change could become the main cause of the decline in biodiversity", according to a statement from the German Centre for Integrative Biodiversity Research (iDiv).

On the other hand, a global meta-analysis of 186 studies reveals that conservation actions -- especially those targeting species and ecosystems -- have significant positive impacts on biodiversity, according to a statement from the American Association for the Advancement of Science (AAAS).

In the case of the first study, the "largest of its kind", researchers from iDiv and the University of Halle-Wittenberg (MLU) compared 13 models to assess the impact of changes in land use and climate change, taking into account four biodiversity metrics, as well as nine ecosystem services.

"By including all regions of the world (...), we were able to fill many blind spots and respond to criticisms of other approaches based on fragmented and potentially biased data", says Portuguese Henrique Pereira, a conservation biologist and leader of the group of scientists who participated in the study, who is the first author of the article.

"All approaches have advantages and disadvantages. We believe that our approach (...) provides the most comprehensive estimate of biodiversity trends worldwide", he added, quoted in the statement.

The researchers calculated the impact of changes in land use on ecosystem services, or "the benefits that nature provides to humans", and analysed how these and biodiversity could evolve, taking into account the growing importance of climate change.

In the three scenarios evaluated -- from sustainable development to high greenhouse gas emissions -- "the combined impacts of land use changes and climate change result in biodiversity loss in all regions of the world", although there are "considerable variations" between the areas.

"The purpose of long-term scenarios is not to predict what will happen", but "to understand the alternatives and, therefore, to avoid the trajectories that may be less desirable and choose those that have positive results. The trajectories depend on the measures chosen and these decisions are made day by day", explained Portuguese biologist Inês Martins, from the University of York and co-author of the article published in Science.

In this context, the discovery made through the meta-analysis published by the AAAS becomes relevant, namely that "in two-thirds of the cases, conservation actions had a positive effect, improving the state of biodiversity or at least slowing its decline".

The team of researchers led by Penny Langhammer, assistant professor of biology at Arizona State University and executive vice president of the non-governmental organisation Re:Wild (which advocates for the recovery and protection of biodiversity worldwide), revealed that the most effective and impactful interventions are those "aimed at species and ecosystems, such as invasive species control, 'habitat' recovery, protected areas and sustainable management".

Despite billions of dollars being spent each year on conservation actions aimed at "stopping and/or reversing biodiversity loss and ecosystem degradation (...) many international conservation goals, including those set by the Convention on Biological Diversity, remain elusive".

The study argues that, in order to determine future measures, an in-depth assessment of policy objectives and an analysis of the results of current conservation interventions in terms of biodiversity are necessary.

And, to reverse the global diversity crisis, conservation actions must be increased and applied more widely, which "will require significant additional investment in many sectors of society", Penny Langhammer and her colleagues say.

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