Climate Change Wreaks Havoc on Mexican Ecosystems

Climate change affects biodiversity in the world; there is evidence of disturbances in biological and ecological processes at different scales of organization, from the genetic level to the ecosystem level, reveals the report State and perspectives of climate change in Mexico: a starting point.

The document, coordinated by the Climate Change Research Program and the Institute of Atmospheric Sciences and Climate Change (ICAyCC) of UNAM, establishes that it will exacerbate the effect of other anthropogenic factors that are threatening species and ecosystems, such as habitat loss, invasive species, pollution and outbreaks of pathogens, among others.

“Mexico is recognized for its high diversity of species and endemisms, being located in a biogeographic transition zone between the Nearctic and Neotropical regions. This heterogeneity makes it particularly vulnerable to climate change, and it is a priority to understand how this phenomenon affects biodiversity and how the combination of ecological traits and evolutionary history could help to understand the way in which species respond to changes in climate regimes,” explained ICAyCC researcher Julián Velasco Vinasco.

The expert acknowledged that the information available to date on the impacts is quite poor and dispersed, especially for this region of the world. Hence, the interest in increasing scientific studies on this topic in Mexico.

Velasco Vinasco highlighted five threats that harm biodiversity in the country: deforestation, habitat loss, land use change, pollution and invasive species.

Some data

Among the documented data, it is known that since the 1970s there have been drastic reductions in the area covered by hard corals in the Mexican Caribbean, both due to the consequences of global warming and natural climate variability events.

In the coastal and marine systems of the Mexican Caribbean, the number of hard corals has decreased dramatically, from 50 percent of the reef floor covered by them to 10 percent at present.

Despite their importance for ecosystem-based adaptation strategies and for mitigating impacts from extreme events, little is known about the consequences of contemporary global climate variability on mangroves, dunes and seagrasses.

These ecosystems are essential for regulating and protecting against the repercussions of extreme events such as tropical cyclones. Research on this subject is a priority, as is undertaking restoration and conservation actions, Velasco Vinasco stressed.

Meanwhile, the document states that there is evidence of local extinctions of at least 12 percent of the populations of 48 species of lizards of the genus Sceloporus due to increases in maximum and minimum temperatures, in addition to declines in populations of forest species such as oaks and conifers.

In birds, there is evidence of changes in species composition in some regions of the country throughout the 20th century. In particular, desert areas (Chihuahua, Sonora, northern Baja California) and the Usumacinta River basin are reported as the areas with the highest rates of local extinction and replacement.

Altitudinal migrations have been documented in different types of vegetation. “Remote sensing has recently been used to assess whether tree line elevational limits in mountainous regions of Mexico have changed between 1985 and 2018. Elevational migrations of at least 500 meters were documented in forests and grasslands on 15 volcanoes in central Mexico over a three-decade period,” the expert said.

What is expected?

In future projections, the study indicates that some regions could be more susceptible to gains and losses of distribution areas in endemic species.

Local extinctions and reductions of up to 50 percent of the current size of distribution areas are expected in several taxonomic groups, mainly terrestrial vertebrates.

In cases such as birds and amphibians, threatened and ecologically restricted species will suffer a more marked negative impact under future climate change scenarios.

The greatest species losses for amphibians are projected for the southern regions of the Gulf of Mexico and the Yucatan Peninsula. Similarly, some studies estimate drastic reductions of more than 60 percent of the habitat for pine species in our country.

Due to the consequences, it is necessary to expand scientific studies of groups of animals, plants and particular ecosystems to carry out more future scenarios, which implies greater participation of professionals and investment in the sector, concluded Velasco Vinasco.