by Jessica Garrity
In order to understand the impact that climate change will have on biodiversity, we must first understand biodiversity. Biodiversity is defined as “the variety of life in the world or in a particular habitat or ecosystem.” Biodiversity is extremely important, partly because having a wide variety of plants and animals provides us with a wide variety of resources. Many of our medicines are derived from plants, and,as we all know, each species in an ecosystem plays an important role in the food chain.
Why is climate change threatening biodiversity?
A changing climate alters the ecosystems in which plants and animals (and people) live. Ecosystems closer to the poles are especially vulnerable to climate change, because rising temperatures are having a greater impact at higher latitudes. Also, two-thirds of the surface of our planet is covered in oceans, which are also receiving the brunt of climate change impacts. Due to the fact that no ecosystem is discrete (that is; they are not completely separated from the ecosystems and habitats around them) and also that we often rely on resources that are found in completely different biomes from where we live, it is extremely important to take into account the effect climate change is having on biodiversity worldwide. Although the effects of climate change are evident all over the world, some of the most rapid and severe loss of biodiversity is occurring at high latitudes and in the ocean.
- Impacts at High Latitudes
The Arctic and Antarctic, in addition to other high latitude areas, are subject to the highest rates of warming. We are all familiar with the image of polar bears struggling to find sea ice, and the decline of large animals in any ecosystem is often perceived as an indicator of significant decline. However, the issue of polar ice loss is much deeper and more concerning than a loss of polar bears. Ice and snow reflect light, while dark ocean water absorbs light, for the same reason You experience the same phenomenon if you feel warmer while wearing black on a summer’s day than if you wear white. The less ice that remains, the more heat is absorbed by the water, which means warmer water and higher rates of melting.Therefore, melting polar ice creates a positive feedback loop that promotes further ice loss.
If all the sea ice in the Arctic melts during the summer months, an entire biome will be lost. The loss of the Arctic biome will then set off a chain of consequences that will affect the entire food web, starting with the algae that forms on ice that has been there for multiple years. When this algae is unable to grow, invertebrates and plankton that feed on the algae lose their primary food source. Birds, fish and marine mammals that feed on the invertebrates, plankton, or the fish that eat the invertebrates and plankton may also lose their food source. Unfortunately, the consequences of polar ice loss do not end at the food web; without ice, arctic birds will be unable to land, mate, or nest, while arctic seals will have no place to rest or raise young. These are only two examples of the many organisms that will be negatively affected by polar ice loss.
These impacts are not confined to the poles either. Warmer water and lack of sea ice can have impacts on ocean circulation that will affect weather patterns around the world, as well as many of the resources for which we depend on the ocean.
- Impacts on the Ocean
According to Ove Hoegh-Guldberg, the director of the Global Change Institute, the melting of ice and warming of waters drives the ocean toward conditions that have not been seen for millions of years and will cause death, extinctions, habitat loss, alteration of fundamental processes, and a necessity for community assemblages to be reorganized. He also states that “ecological surprises are likely.” Since the types of changes to come have never been seen by humans, it is nearly impossible for us to predict their severity or extent.
A few of the changes that we are already seeing include ocean acidification, an increasing number of dead zones, and ocean stratification. Ocean acidification occurs when atmospheric CO2 and other greenhouse gases are absorbed by the ocean. The absorption increases the acidity of the ocean (the ocean still remains slightly basic, but it pushed toward a more acidic state), and the acidity greatly affects certain animals’ ability to create calcium carbonate shells. For example, any animal that creates a shell with calcium carbonate may experience slower growth rates, or even dissolution of their shell. This includes clams, scallops, oysters, snails, sea butterflies, corals, and the main producers in our ocean which are phytoplankton. Again, not only will we see this direct effect on these invertebrates but we will also be able to follow the effects right up the food chain.
Ocean stratification describes the phenomenon in which cold ocean water and warm ocean water separate. The warm water tends to stay on top of the cold, and while this may sound great to beachgoers, the cold ocean water is what contains the nutrients necessary for surface-dwelling phytoplankton to survive. Phytoplankton are like the tiny plants of the ocean; they use sunlight to produce food, and therefore must remain at the top 100-200m of the ocean. When cold, nutrient rich water is not mixing at the top layers where sunlight can reach, the phytoplankton cannot survive. And for all you humans out there saying “who cares about phytoplankton,” keep in mind that phytoplankton produce around 50% of the oxygen in our atmosphere and provide the basis of the food web for all fisheries.
I have focused on high latitude and oceanic impacts because those are the places where we are seeing the highest rate of change, and the severest threat to biodiversity is in those areas. However, biodiversity loss due to climate change is a global problem. it is estimated that 15% of bird species, 25% of mammals, 25% of coniferous trees, 33% of amphibians, and up to 87% of marine turtle species will be extinct by 2080. It is also estimated that 25% of lizard species could be wiped out by this time. Although I understand that, as a biologist, I tend to be a bit more passionate about saving animals and ecosystems, but as a realist I also understand that a decrease in biodiversity is also a decrease in food supply, medicines, building materials, and any other product or service derived from plants and animals.