Most primates – monkeys, great apes, lemurs, lorises and tarsiers – live in a tropical belt that stretches around the equator from Central and South America to Africa and Asia. But the majority of them are in four different countries – Brazil, Madagascar, Indonesia and the Democratic Republic of the Congo – so many people have not had direct contact with them.

However, we may know them from films, like the Capuchin in Pirates of the Caribbean, or may have heard of their stealth abilities, like the macaques that pickpocket travelers. Some are important cultural or religious symbols, like macaques.

These animals also play a key role in their ecosystems, pollinating flowers and dispersing seeds. Although there are around 500 species of primates in the world, three-quarters of them face population declines.

Because most primates live near the equator, many are particularly vulnerable to climate change. In a recent study, my colleagues and I looked at what would happen to primate species around the world if global temperatures rose by 2 ° C, the upper limit set by the Paris Agreement. The results showed that a quarter of primate habitat will experience prolonged periods of extreme heat. They give conservation scientists important information about how climate change will influence primate populations in the future.

New extreme heat

We already know that global warming will not be uniform across the planet. The Arctic is warming faster than places closer to the equator, for example. But for animals already living in warm places, a slight increase in temperature could easily move them past a threshold and out of their comfort zone.

The threshold temperatures in our study represent the hottest temperature each primate species would have faced in pre-industrial times. We then compared the future average temperatures to this benchmark.

Under the Paris Agreement, countries pledged to keep global warming 2 ° C above pre-industrial levels. Yet, we found that in this scenario, 26.1% of all habitats where primate species live will be warmer than their threshold temperatures. For some species, such as the patas monkey and the Senegalese bushbaby in Africa, this could mean long periods throughout the year where temperatures exceed 33 C.

Like humans, primates overheat and become dehydrated with continued physical activity in extremely hot weather. In a warmer future, they are expected to adapt, rest, and stay in the shade during the hottest hours of the day. This could mean less food or not mating, which could limit overall food intake and alter reproductive cycles.

Species living in the Brazilian Amazon, along the northern coast of Venezuela, central equatorial Africa, the east African coast and the northwest coast of Madagascar will be the most affected. Those that are already at risk, have populations occupying less than 12,000 square kilometers, and face significant temperature increases – such as annual averages consistently above 27 ° C – are most at risk of extinction with aggravating effects. of climate change.

For example, the Celebes crested macaque (the famous ‘selfie monkey’ primate) and the Siau Island tarsier are both critically endangered in small habitats, while currently experiencing temperatures throughout the world. years above their historical thresholds.

Our analysis also showed that climate change has already pushed eight percent of the habits of primate species beyond their thresholds. This means that some populations may face additional stress from the warmer temperatures and the change in behavior to compensate. These species all have declining populations and have been classified as close to extinction – the new extreme heat could be partly to blame.

Human impact

It’s easy to assume that warmer global temperatures would lead to an increase in the preferred habitat of primates, stretching it north and south and up on mountain slopes. But due to the growth of human population, infrastructure and agriculture, some species might not be able to move to these newly adapted areas.

Many primates prefer to avoid us and our roads, towns and fields prevent them from getting there. In some cases, there is no habitat to move to because it has been cut, mined, or otherwise degraded.

About 60% of non-human primate species are currently threatened with extinction, and climate change is only one part of it. Habitat loss, hunting, the illegal pet trade and disease have already reduced primate populations. Climate change is likely to increase the duration and intensity of extreme weather events such as cyclones and droughts, putting more pressure on the survival of already struggling species.

Conservation is the key

Our model did not include conservation issues, such as habitat loss, that primates already face. Yet areas with the most primate species expected to exceed temperature thresholds have also been identified as conducive to the expansion of oil palm plantations. The combination of the two would only further reduce these species’ access to suitable habitat and put them at greater risk of extinction.

Nature reserves have helped maintain populations of wild animals. However, the boundaries of wildlife reserves and protected areas are generally fixed and difficult to move. Future increases in temperature could alter the habitat in a protected area so that it is no longer suitable for the primate species that currently inhabit it.

Given the rapid pace of climate change, future conservation of primates should include predicted temperature changes in combination with other issues facing primates. For example, the boundaries of wildlife sanctuaries could be chosen based on the future climatically appropriate habitat for a species. Primates are amazing and fascinating animals that deserve a home on this planet by our side.

Brogan M. Stewart, doctoral student in environmental science, Concordia University

This article is republished from The Conversation under a Creative Commons license. Read the original article.