Are Human Land Uses Becoming Too Hot to Handle?


Almost 3 years ago I started my PhD with the aim to explore the impacts of habitat change on wildlife, specifically focusing on how animals are affected by the changes in temperature and rainfall following land changes. At the end of last year, I published a paper (yay!) aimed at answering this question. Here, I am going to give you a breakdown of why this topic is important, what I found out and the implications this has for wildlife (basically, the interesting and important parts)! So, let’s begin…

The Background

The number of humans on Earth is rapidly increasing – by 2050 there will be an estimated 9.7 billion of us (1)! Consequently, the demand for food, water, building materials and other resources is also growing. These demands lead to greater areas of land being transformed (as seen below) away from their natural state (e.g. forests and grasslands) into human-altered land uses, such as croplands, pastures, plantations or urban areas.

Habitat change and loss currently pose the greatest threat to wildlife (2). The transformation from natural to human land uses not only destroys animal’s homes, it can also remove food sources, cut off migration paths and force animals to live closer together (increasing levels of conflict between individuals – imagine you and your neighbours suddenly having to share one house; I can definitely see this leading to arguments!).

There has been a lot of research looking at these impacts of habitat transformation. However, more recently, another impact of land conversion has come into scientists’ focus (3). When natural habitats are transformed by humans, to agriculture or urban areas for example, it also changes the local climate (4,5).

Let’s go on a quick little adventure: imagine yourself walking through a woodland on a hot, sunny day. If you’re underneath the shade of the canopy layer, it’s cool, and you can walk comfortably without overheating. Now imagine you come to the edge of the forest and step out into an open cornfield where the hot sun is glaring down on you. Here, you’ll likely feel hotter and the ground may feel harder and drier. When deciding where to have your picnic, if I were you, I’d go back into the shade of the woodland canopy.

Coming back to reality, human land uses are hotter and drier than natural habitats on average (5). The lack of a canopy layer (the trees keeping you cool in the woodland) means that human land uses often have hotter maximum temperatures and colder minimum (night-time or winter) temperatures (6). In addition, land conversion to human land uses also changes the vegetation present, which impacts processes such as evapotranspiration (water transfer from the land and plants into the atmosphere) and thus the amount of rainfall in the local area (7). I wanted to find out what impacts these changes in local climate have on the wildlife in these human land uses. Personally, I would like it if my local area had less rain and was generally hotter – but is it the same for wildlife?! What if some animals are not able to tolerate these changes in temperature and rainfall? I know if I had to sleep outside overnight, I would not want it to get even colder!

The impacts of these local climatic changes…