The concepts “climate change” and “ global change ” are often confused. It is, in part, logical, since climate change affects the entire planet. But when we talk about global change we are talking about an event that occurs at many levels: climatic, biological, ecological, biogeochemical , and that has consequences on the natural environment as well as on an economic and sociopolitical level .
This global change is anthropogenic, and its causes are interrelated with each other. Today we are going to explore the five main drivers of global change that humans are responsible for.
5. Land use changes
More than half of the land surface is affected by the human hand, in one way or another. It is clear that changing the structure of ecosystems is, in itself, a driver of global change.
Whether in the form of urbanized land , pastures, forestry, mining and above all, agricultural land , which already occupies a third of the total area. All this causes, among many other things, the fragmentation of forests. In tropical regions, only 20% of the forests cover more than 500 km². A value that in the last 10 years has fallen by more than 7%.
Changes in land use generate its degradation , altering its physical, chemical and biological properties. It also changes the way in which the soil erodes, facilitating desertification, modifying chemical cycles and, ultimately, putting human populations in contact with wild animals, which can cause the disappearance of species and the appearance of new diseases.
4. Overexploitation of resources
The exploitation of natural resources is closely related to the change in land use. But let’s talk about an essential resource whose overexploitation is, perhaps, the one that contributes the most to global change: water.
During the 20th century, it is estimated that annual water consumption increased from about 600 km³ to about 4,000 km³ . higher than demographic growth. Again, the main causes are agricultural use and industrial use —69% and 19% respectively—, while human consumption barely occupies 12%.
Together with the fragmentation of habitats, the depletion of water favors erosion and desertification ; the loss of wetlands directly affects biodiversity and can feed back into climate change. But in addition, by reducing the available drinking water and its quality, food security is threatened and can lead to conflicts between peoples.
3. Pollution
All forms of pollution contribute to global change. Air pollution contributes to climate change, while water pollution feeds back into the overexploitation of water. Solid waste , such as abandoned fishing nets or fishing lines, can lead to the amputation of animal limbs and even the stranding of cetaceans.
But one of the most relevant pollutants in recent decades is that of plastics. Every year, millions of tons of plastic are dumped from rivers into the oceans. Discharge from Asian rivers accounts for two-thirds of the total.
Plastic waste is very difficult to dispose of, and has already affected 44% of seabird species and 43% of marine mammals. As for microplastic particles, it is estimated that up to 25% of the fish we consume is contaminated.
2. Invasive alien species
Currently, the introduction of exotic species into new ecosystems is considered the greatest cause of biodiversity loss , as well as the second most important driver of global change, only after climate change.
Invasive alien species have doubled in the last half century, and have a series of impacts, both environmental and socioeconomic. They displace native species, either through competition, predation, disease transmission or even hybridization, and sometimes lead them to extinction. Some are capable of altering the structure of habitats and modifying nutrient cycles.
From a social and economic point of view, they can have serious impacts on agriculture, forestry, livestock and infrastructure, seriously affecting the economy. And they can be vectors of diseases that can be transmitted to humans, putting public health at risk .
1. Climate change
Climate change is considered the main driver of global change. The causes are clear: the emission of greenhouse gases, mainly produced by the burning of fossil fuels and, secondarily, by industry and livestock. Among its effects, the rise in sea level, ocean acidification, the displacement or disappearance of entire ecosystems, the loss of agricultural productivity… and a potential collapse of biodiversity that, if it happens, could lead to the sixth great extinction en masse in the history of the planet.
As we have said, global change is an event on a planetary scale, which is caused by many engines.
These five main causes, which are related to each other and feed each other, are all caused by human activity, and have serious impacts on us, fomenting geopolitical problems and increasing the
social inequalities . Some we can mitigate, others we can prevent from recurring, and in some cases it will take a lot of effort to find ways to circumvent their effects. We can all contribute our grain of sand, but the ultimate responsibility lies with the great superpowers and the industries that, in one way or another, continue to promote these activities.
REFERENCES:
Balvanera, Patricia, Pfaff, Alexander, et al. 2019. Status and Trends –Drivers of Change. En Global assessment report on biodiversity and ecosystem services of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (Brondízio, E. S., Settele, J., Díaz, S., Ngo, H. T.). IPBES secretariat. DOI: 10.5281/ZENODO.5517423
