Agricultural systems in many parts of the world are under serious threat from both the effects of climate change and deafaunation. Increasing outbreaks of diseases such as Ebola are clearly linked to deafaunation.
According to solid research work, 320 terrestrial vertebrate have become extinct since 1500, with the pace of extinction vastly speeding up over the past 100 years. This is so serious that it is being called the world’s 6th major extinction. The causes are both climate change and defaunation. The effect on agriculture is clearly catastrophic especially in over-populated countries. But this whole problem has been overlooked in favor of spending more on fertilizers, pesticides and GMO crops, all of which provide temporary fixes.
In this program, professor of Biology Rodolfo Dirzo from Stanford University and Professor Gerardo Ceballos, from the Instituto de Ecologia, at the National Autonomous University of Mexico and Visiting professor at Stanford University, explain this issue.
Why is this called the world’s 6th mass extinction?
Pr. Dirzo: The main characteristic of this ongoing extinction is that, in this particular case, it is one factor that is the main driver of the process. In this case it is the humans – homo sapience. It is very much in contrast to what happened during previous extinctions, in which it was a natural phenomenon, a catastrophic phenomenon, such as a meteorite or something like that.
The problem that climate change is happening at the same time with defaunation, this a compounding effect, isn’t it?
Pr. Dirzo: Exactly! We, scientists used to think or used to analyze the factor of the animal life’s loss or extinction in general to be driven by the elements such as the destruction of habitats, on the one hand. Perhaps, that’s been the most well recognized factor of extinction. Second is the overexploitation of animals.
And then, you have things such as environmental pollution, contamination and then evasive species, and, lately, the climate change. But what we are trying to emphasize in our study is that we should move from the idea of just considering one factor at a time. Unfortunately, as we move forward, all of those factors are combining amongst themselves to create a much more dire situation.
But nature changes slowly. Changes have occurred in my lifetime, but we have somehow learnt how to get round them.
Pr. Dirzo: The service of the pollinators, the ecosystem services, that could be translated in economic terms, in about 10 percent of the total cost of food production in the world. Losing the pollinators would imply the reduction of the capacity of 75 percent of all crops to be pollinated, seasonal fruits and about 10 percent of the food production globally. In the case of animals that play a very important role as the controllers of agricultural pests, many pests are controlled by other animals. And so, losing those animals that operate as biological controllers also represents a dramatic impact on our food production system.
In the case of the US alone, for example, the loss of the animals which control pests in the agricultural system, that represents about $4.5 billion on an annual basis. So, that is really-really significant from the point of view of food production and from the point of view of economics as well.
And this could happen in our lifetime?
Pr. Ceballos: So far, it seems to be gradual and we are used to that. It is a gradual loss of the species and the environmental services have been able to cope with it. But now we are really reaching a tipping point. In our lifetime there could be a huge collapse.
Let me give you an example for our audience. You have a wall out of bricks. If we have been taking the bricks out of that wall, that wall starts functioning less properly. There is wind or noise, or whatever, but the wall is still there. But then, we are reaching a point when we want to take out another brick (another species out of a set of species), then we have a possibility of whole wall collapsing. This is what is happening with nature. Unless we change dramatically the ways we do business on earth, there is a real possibility of a global collapse between 2040-2050, or even earlier.
So, we are really facing, what we think is the strongest and the hardest, the most threatening problem that the humanity has faced since it emerged. That is the urgent message that we need to act now, because there is no time to teach the children about this.
Pr. Dirzo: The combination of the different drivers of environmental change that we have discussed, unfortunately, as we said, they are operating now in synergy. They are reinforcing themselves. And that has led us to collectively come to the conclusion that we are really taking about just a few decades. A common consensus is that by the 2050’es the situation might come to a point in which you remove the last brick, the last rivet of a structure and that can actually cause the collapse.
And of course, we know that the planet has experienced those kinds of situations in the past. We do know that that is a real ecological phenomenon. It is called a paradigm shift, it is called a paradigm change in ecological conditions. When the dinosaurs went extinct, after that the world did not disappear as a whole, but the world was modified in such a way that life had to be in a very different way.
