The climatic risk of Amazonian protected areas is driven by climate velocity until 2050

high forward velocity or disappearing climates are ultimately under threat of extinction. Alter- natively, backward velocity reflects the shortest distance that an organism in the current land- scape would have to migrate to colonize a particular newly suitable habitat given the projected future climate. A high backward velocity indicates a potential risk for sites on holding species adapted to its future climate. Accordingly, a future climate that lacks a current climate analog is classified as a "novel climate". Therefore, cells with high backward velocity or novel climates are ultimately under threat of becoming unsuitable habitats, with consequent effects on ecosys- tem function and services. Whilst forward velocity measures the distance from a single origin to multiple future destinations, backward velocity implies the distance between multiple origin points to a single future destination. Consequently, the use of these two metrics in planning will result in a contrasting focus on species/populations (forward velocity) or sites (backward velocity) [20, 21]. The ecological interpretation of the effects of climate velocity is often associated with the movement of species, which relies on the assumption that species will not be able to acclimate or adapt to shifting climate and thus need to move to track suitable climates. Observed evi- dence from long-term forest dynamics in Costa Rica, Panama and Malaysia indicated that trees have declining growth rates in response to regional increases on temperatures [22, 23].

Further, evidence from a long-term drought experiment in the Amazon indicated no change in the overall thermal sensitivity of net photosynthesis or foliar respiration rates in response to reduced precipitation [24]. Both studies indicate that individuals may be unable to acclimate physiological processes to changing climate. Similarly, long-term inventory plots have indi- cated that long generation times of tree communities are lagging behind increases in moisture stress [25]. By contrast, a long-term collection of morphometric data on a nonmigratory understory bird community within Amazonia suggested that other components of biodiversity are potentially already responding to climate change through morphological shifts [26]. In this work, the potential ecological implications of the climate change velocity metric will be dis- cussed assuming the premise that most species will not be able to acclimatize and, therefore, will respond to climate change through spatial changes. To understand the underlying causes that determine the climate risk of different areas, cli- matic velocities provide two valuable pieces of information. For example, for areas that have analogous climates, the magnitude of velocity is determined by the distance between analogous climates. In this context, climate velocities depend, to an extent, on the geography of the study area, which was not investigated in this study. Alternatively, for areas that have no-analog cli- mates, climate risk is determined by the magnitude of the climatic variables used, as their val-

ues escape the historical variability of the study region. As the multivariate definition of climate analog was used, there is no single temperature or precipitation threshold that deter- mines the presence of no-analog climates. Rather, the definition of no-analog is a result of the lack of equivalent precipitation and temperature values within the historical variability of all cells within the study area. The Amazon has been ranked amongst the global regions most at risk of developing new climatic conditions [3], and developing the greatest distances between current and future (2100) equivalent temperatures [27]. Previous velocity studies carried out at macroclimatic scale and considering only temperature, have overestimated velocities in regions close to the equator, driven by the dominance of flat areas [28]. The only visualization [20] of the spatial distribution of analog-based climate velocity for the Amazon to date is at macroclimatic scale (50x50 km). The application of finer scales such as meso (1-10km), topo (10m-1km) or micro- climatic (<50m) is therefore essential to identify refuges and other areas where conservation may facilitate the persistence of biodiversity under climate change, even within potentially unsuitable regions [29]. Using the 5km x 5km scale, other studies [12, 30] have sought climatic PLOS ONE Amazonian protected areas and climate velocity PLOS ONE | https://doi.org/10.1371/journal.pone.0286457 June 22, 2023 3 / 14