Characterization, variability and long-term trends on local climate in a Mexican tropical dry forest

Based on 40 years of meteorological data, we characterized and analysed long-term climatic trends in the Chamela-Cuixmala Biosphere Reserve on the Pacific coast of central Mexico. The region is still covered by a large proportion of well-preserved tropical dry forest, characterized by a short period of rain and a dry season of around 8 months. We found a sustained temperature increase which is likely driven by global climate change. An increasing trend in rainfall was also found, but the trend was detected only during the wet season. Correspondingly, an increase in runoff during the rainfall season was also detected; this seems to be linked with an increasing number of intense rainfall events, rather than an increase in the total number of rainy days. El Nino years are likely to present below average precipitation during the wet season and above average precipitation during the dry season. The opposite is expected during La Nina years, when tropical cyclones are likely to come closer to the coast and cause intense rainfall events during the hurricane season. As many of the studied variables are likely to change under climate change scenarios, our results highlight the need to understand the expected impacts of global climate change on tropical dry forests. In particular, it is necessary to monitor changes in water availability to anticipate its consequences for the forest and the human communities that depend on it.