When nature is replaced by agriculture, this has consequences for biodiversity around the world. Photo: Shutterstock
There is more pressure than ever before on biodiversity. Is it still possible to reverse the downward trend of declining biodiversity? Wageningen professor Rob Alkemade has been working for years on an all-encompassing computer model that is capable of calculating scenarios for the future with increasing accuracy. It shows which levers we need to pull – and how hard – in order to turn the tide.
Around the world, the number of species of plants, animals and other organisms is declining faster than ever before. Key factors driving this downward trend are global warming and the use of land for purposes such as food production. In addition, excessive nitrogen is being deposited in some nature areas and other harmful substances are getting into the environment. At the same time, other nature areas are enjoying better protection and there is more room for nature in our cities. But is that enough to guarantee a future with sufficient biodiversity?
Firm figures on global biodiversity are in short supply. After all, each region is different. Yet scientists are trying to get a more and more accurate estimate of the actual situation. Rob Alkemade is one of these scientists. He builds computer models of global biodiversity in his work for the Netherlands Environmental Assessment Agency and as a professor holding an endowed chair in Modelling Biodiversity and Ecosystem Services at Wageningen University & Research (WUR).
Model for the future
He started on his current model twenty years ago. All those years working on it mean that Alkemade, who is affiliated with the Wageningen Institute for Environment and Climate Research (WIMEK), can produce increasingly accurate future scenarios, comparable to the climate scenarios of the Intergovernmental Panel on Climate Change (IPCC). Put briefly, the approach is as follows: it starts with the collection of large amounts of data from earlier studies, followed by calculations of the relationships between these data and environmental variables, the creation of environmental pressures and species distribution maps, and finally playing with the model to find out what is needed to reverse the trend.
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Combining all the maps and data lets you see how habitats shrink or expand
If the approach is chosen of large, protected nature areas without people living there, the Netherlands will be used mainly for agriculture and the major nature areas will be found elsewhere in Europe. Photo: Shutterstock
“We use two methods to build the model,” explains Alkemade. “First, we collect data on the difference between the number of species, and their population sizes, in a natural situation and the number in an unnatural, disturbed or polluted situation. We derive relationships from that data that we then apply to maps showing the changes in land use.” As forests are felled to create farmland, for example, that results in a certain reduction in the number of species of insects. “Our second method is to take species distribution maps and compare them against data about the climate and water, for instance. That shows you how habitats are shrinking or expanding. When the maps that result from the two methods are combined, you get a picture of the change in biodiversity.”
Each region is different
The current models factor in a greater range of threats to biodiversity than two decades ago. Alkemade cites changes in land use (for example nature turning into farmland), nitrogen, the climate, the fragmentation of nature areas and the effect of roads. “That already constitutes a major expansion in the models, but we are going further. Initially, we just had a few broad categories for agricultural areas, such as pasture, crops or woodland. Now we will be distinguishing between different types of management. It makes a difference whether or not farmers take nature-friendly measures. In cities too, you have densely built-up areas and parkland. Unfortunately, we don’t yet have enough data to take these differences into account, but we are adapting the model in anticipation of that data.”
The relationship between humans and nature is far more grounded in Bolivia. Photo: Shutterstock
Alkemade builds these detailed models so that policymakers can make well-founded decisions about the future. So this is just the first step in mapping biodiversity on a global scale. However, it is a crucial one because it serves as the basis for the next step: drawing up scenarios for the future. These scenarios predict what will happen if certain measures are taken today. They show which levers we can pull – and how hard – in order to reverse the trend.
Everyone has their own view of nature
When drawing up future scenarios, Alkemade adopts a different, more sociological stance. “Everyone has their own views on nature and biodiversity. Nature could look very different depending on the different perspectives.” Broadly speaking, there are three perspectives. Some people think humankind and nature should be segregated. They are in favour of large, protected nature areas where no people live. “If you choose that approach, the Netherlands won’t get much more nature because the land here is well suited to agriculture. You will find the larger nature areas in other parts of Europe.”
The aim according to the second perspective is to make optimum, and therefore sustainable, use of nature. “Examples are forestry, nature as a source of fruits, recreation, natural pollination and pest control,” says Alkemade. In the third perspective, no distinction is made between humankind and nature. According to Alkemade, many people in South America and Asia take this more cultural, bonding view of nature. “But this perspective exists in Western societies too. We feel a bond with the tree around the corner; we don’t want it chopped down.”
The question is which view of nature enables us to halt the deterioration in biodiversity. The good news is that this is possible with both the first and the second perspective. It is not so easy to perform the calculations for the third perspective. Alkemade: “We don’t know exactly what nature would look like if everyone took the attitude that humans are at one with nature.” There is quite simply not so much concrete data on how nature would change in that case and by how much.
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We drew the same conclusions in our first report, but the calculations twenty years on are much more precise
When roads are built, which leads to nitrogen emissions, the impact on the surrounding nature must be kept to a minimum. Photo: Shutterstock
Incidentally, Alkemade says everyone embraces all three perspectives to some extent. Which perspective dominates depends on the situation. The next step now is to work out scenarios for the future that take all three perspectives into account.
Pointing to a combined approach
When Alkemade compares his recent research with older work, he sees that the general conclusions from his research have not changed. “We drew the same conclusions in our first report published twenty years ago. But our calculations are much more precise now. We have data on more areas and more species, and we take a much broader look at the consequences of changes on biodiversity. The most significant contribution of analyses like this is that they are a constant reminder of the importance of a combined approach because otherwise you will not be able to achieve the international targets for biodiversity, let alone reverse the trend and bring about an increase in biodiversity.”
In addition to achieving the UN’s sustainable development goals, which focus on aspects such as combating poverty, improving education and health and ensuring clean water, more needs to be done to reach biodiversity objectives too, for example by fighting climate change and pollution and by reducing meat consumption. In agriculture, two routes can be taken: intensive agriculture in combination with large nature areas, or more nature-friendly agriculture. Alkemade: “The main things we need to do in the Netherlands are to drastically reduce nitrogen emissions, change water management to prevent desiccation, and take a range of measures to encourage nature restoration, for example by expanding woodland, restoring river watercourses, and reintroducing natural elements such as hedgerows in the landscape.”
While the challenge of calling a halt to the decline in biodiversity by 2050 is enormous, Alkemade is cautiously optimistic. “I have mixed feelings. I see a lot of positive things happening, even if it is taking far too long. The constant repetition of the message to eat less meat is leading to an increase in vegetarian consumption, including in other countries. People are going to court to enforce reductions in CO₂ and nitrogen emissions because binding agreements were made on this. That movement has momentum. While we still see diametrically opposed developments, such as the loss of forests, people increasingly find that unacceptable, which I find a promising sign.”
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Read more about the global biodiversity model GLOBIO
Read more about the research of the Wageningen Institute for Environment and Climate Research (WIMEK)
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