Climate change threatens the most biodiverse regions of Mexico
Graphical abstract
Introduction
Rapid modern climate change is already altering species distributions and reorganising the composition of many ecosystems (Lenoir and Svenning, 2015). These changes have important direct and indirect consequences on ecosystem functioning, human health, and climatic feedbacks (Bonebrake et al., 2018; Pecl et al., 2017; Scheffers et al., 2016). Thus, projected increases in temperature, shifts in precipitation patterns, and the increasing occurrence of extreme weather events jeopardize the persistence of ecosystems and the species they support (Field et al., 2014).
Effective conservation and management practices depend strongly on our ability to predict the impacts of climate change on natural and human-managed ecosystems (Mawdsley et al., 2009). However, predicting the impacts of climate change is particularly challenging, due to the complexities of climatic processes and uncertainty about the rate and magnitude of changes (Baumgartner et al., 2018; Beaumont et al., 2019; Fatichi et al., 2016; Grierson et al., 2011; Loarie et al., 2009; Ohlemüller, 2011). As changes in climate intensify, assessments of the extent to which the available climatic space may change are particularly important in order to identify species most threatened by changing climate (Guisan et al., 2014).
During past abrupt climatic changes, populations persisted in areas with relatively stable climate, referred to as refugia (or microrefugia). These areas apparently retained local environmental conditions suitable for species persistence, amidst regionally unsuitable conditions (Correa-Metrio et al., 2014; Médail and Diadema, 2009; Tzedakis et al., 2002). Thus, refugia are recognised as important areas fostering endemic biodiversity (Harrison and Noss, 2017). Although the concept of refugia has been more commonly applied to historical periods during the Quaternary, the idea that some areas may act as potential refugia (or microrefugia) under contemporary and future anthropogenic climate change is now widely accepted by the scientific community (Hannah et al., 2014; Keppel et al., 2012; Keppel and Wardell-Johnson, 2015). Hence, maintaining a functional network of protected areas that retain a sufficient proportion of their existing climatic space into the future will limit biodiversity losses associated with rapid climate change, promote the delivery of ecosystem services, provide livelihoods, and sustain local communities (Ervin, 2003; IUCN, 2005).
Mexico is a megadiverse country harbouring almost 10% of the world's biodiversity (Challenger, 1998; Mittermeier et al., 1998; Sarukhán Kermez and Dirzo, 1992). Currently, the Mexican natural protected areas (NPAs), administered by the National Commission of Natural Protected Areas (Comisión Nacional de Áreas Naturales Protegidas; CONANP), cover >25.3 million ha (Vargas Márquez et al., 2011). Such a large network has the potential to provide refugial capacity (sensu Keppel and Wardell-Johnson, 2015) for ecosystems and adjacent areas, facilitating the maintenance of populations, water quality, nutrient cycling, and ecological flows (DeFries et al., 2010). These NPAs provide habitat for species considered endemic, threatened, or endangered (Batisse, 1982; Ishwaran et al., 2008). Because of the significance of these NPAs, we highlight the importance of understanding the exposure of these ecosystems and the species they harbour to risks associated with future climate change. This understanding is essential for developing and designing effective management and conservation programs (Cash and Moser, 2000). Such a task, in turn, requires the use of approaches and tools that can be applied to species, taxonomic groups, and regions to propose and design a climate-ready protected area network (Graham et al., 2019). One such approach is an assessment of the climatic space that is currently available and how this may be altered by modern rapid climate change.
Here, we evaluate the magnitude of climate change to which species and ecosystems in 40 of Mexico's NPAs will be exposed by 2050. Specifically, we ask three questions: (1) How does climatic space differ across the 40 Mexican NPAs included in this study? (2) How much of the existing climatic space will be retained in the near future (2050)? and (3) Which protected areas are most vulnerable to climate change?
Section snippets
Natural protected areas (NPAs)
Here, we provide a case study of the risks associated with climate change for 40 of Mexico's 174 NPAs, administered by the federal government (CONANP). The 40 NPAs form part of the UNESCO's World Network of Biosphere Reserves and were designed to preserve goods and services provided by the ecosystems they harbour. Six of these NPAs have been named World Heritage Centres as natural assets: (1) Sian Ka'an (Quintana Roo); (2) El Vizcaíno (Baja California Sur); (3) Alto Golfo de California y Delta
Climate change in the natural protected areas of Mexico
Across all NPAs, average conditions for all temperature variables (MTWM, MTCM, TAN) are predicted to increase by 2050, with the exception of a decrease in TAN at Sierra de la Laguna. On average (±SD), MTWM is predicted to increase by 2.8 ± 0.5 °C, with MTCM and TAN predicted to be 2.1 ± 0.2 °C and 0.7 ± 0.4 °C warmer relative to baseline climatic averages (1960–1990), respectively. In contrast, annual precipitation (AP) is predicted to decrease in 30 NPAs, by 34.4 ± 32 mm. Only ten NPAs are predicted to
Climate change in natural protected areas of Mexico
The predicted increases in temperature, and changes in both total precipitation and precipitation seasonality, will likely affect species' ranges, interactions, and even survival (Allen et al., 2010; Anderegg et al., 2015; Field et al., 2014; Thomas et al., 2004; Walther et al., 2002). Within Mexico, temperature is predicted to become warmer across all 40 NPAs by 2050, with larger increases (up to 3.75 °C in MTWM and 2.5 °C in MTCM) predicted to occur in arid regions that already experience high
Conclusion
The capacity of Mexico's 40 UNESCO World Network of Biosphere Reserves to function as long-term refugia for biodiversity is likely to decline as the magnitude of climate change increases. By the mid-century, 31 NPAs, which together provide habitat to at least 22,866 species, are predicted to lose all their baseline climatic space, shifting to novel climates. The extent to which these conditions will be within the tolerance of species and ecosystems is currently unknown.
Author contributions
MER: design of the research; performance of the research; data analysis, collection, and interpretation; writing the manuscript.
LJB: performance of the research; data interpretation; writing the manuscript.
JL: performance of the research; data interpretation; writing the manuscript.
JBB: design of the research; performance of the research; data interpretation; editing the manuscript.
JM: performance of the research; expertise advice on methods; editing the manuscript.
ACM: design of the research;
Acknowledgements
We thank Benjamin Blonder for his comments and contribution to improve this manuscript. We thank the reviewers for their insightful and constructive comments that substantially improved the manuscript.
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