As the previous page indicates, it is clear that the climate is changing, and that these changes are caused mainly by human emissions of greenhouse gases. But this does not explain why we care so much about climate change, and, in particular, why we think climate change is bad. Why climate change is bad depends on our ethical view of what is “bad.” Here we’ll look at both anthropocentric and ecocentric views. In the case of climate change, disruption of ecosystems often also involves disruption to human systems, so the reasons for believing that climate change is bad are largely the same from both anthropocentric and ecocentric ethical views.
The simplest impacts of climate change are shifts in temperatures around the world. Overall, temperatures are increasing. Zones within a certain temperature range are shifting towards the north and south poles and towards higher elevations. Some species, in particular, plant species, are adapted to certain temperature ranges. These species are often shifting to different locations along with the temperature zones. But this shifting is imperfect. First, species may also be adapted to certain elevations or to certain latitudes. Latitude is important for plants because latitude defines how long days and nights are at a given time of year. Second, there may be obstacles impeding the species’ shift. For example, if a species lives on a mountain, it may not be able to cross a valley to get to the next mountain over. Thus some species will not successfully adapt to the temperature shifts caused by climate change. This includes both species in natural ecosystems and species used in human agriculture. (As we will have seen in previous modules, agriculture is always part of an ecosystem, so natural ecosystems and human agriculture are not completely separate from each other.)
Shifts in water
Water patterns are closely connected to temperature patterns. When temperatures are warmer, more water melts and evaporates. This affects precipitation patterns. Shifts in precipitation patterns complicate the process of species adapting to temperature shifts since species are generally also adapted to certain precipitation. For example, a plant might shift towards the north pole to stay within the same temperature zone, but if the precipitation zone does not also shift north, then the plant will have to struggle with different precipitation.
One of the most important shifts in water from climate change is the melting of ice at several places around the world.
In the Arctic Ocean, ice melting is leading to the opening of the Northwest Passage, a sea route between the north Atlantic and north Pacific oceans. The Passage is becoming increasingly navigable, making shipping (especially freight shipping) much less expensive between the wealthy and populous northern nations of Europe, North America, and East Asia. Other countries will be hurt by this, in particular, Panama, whose Canal will diminish in importance.
In central Asia, ice melting in the Himalayas is disrupting water supplies of crucial importance to very large human populations in India, China, and surrounding areas. There is concern about whether these populations will have access to enough fresh water in the future.
In Antarctica and Greenland, large amounts of ice are melting, increasing the amount of water in the oceans. This, in turn, raises sea level. Sea level rise is further increased by thermal expansion: as ocean temperatures increase, the water expands, pushing sea level higher. Ice melt and thermal expansion are causing enough sea-level rise that some low-lying coastal areas could become uninhabitable. This is a particularly serious concern because a large portion of the human population lives in such areas. Many major world cities are threatened, including New York, Los Angeles, Mumbai, Tokyo, Hong Kong, and even London, which is near sea level despite being inland along the River Thames. Already, London has moveable barriers to protect against high tide storm surges. Sea level rise threatens to make the surges more severe.
Extreme weather events
As we saw in Module 8, extreme weather events can cause major disruptions. Climate change is affecting extreme weather events, often by making them more extreme and disruptive. One example of this is hurricanes. Hurricanes get their energy from the warm waters they pass over. This is why the strongest hurricanes occur in warmer regions. As waters warm, they gain more energy, thereby making hurricanes more powerful. For this reason, climate change is expected to increase the intensity of hurricanes and, unfortunately, more intense hurricanes often cause much more damage.
Human and non-human systems alike are adapting and will continue to adapt to climate change. These adaptations are not always successful; the impacts of climate change will inevitably cause harm. But adaptation can reduce the amount of harm caused.
Adaptation raises some large ethical questions. Who should pay for the costs of adaptation: the people who are adapting or the people who emit the greenhouse gases that made the adaptations necessary? It might seem unfair for some people to force other people to adapt, but it is difficult to get emitters to pay when the emitters are everyone across the planet! Another question is: How should we prioritize among adaptation projects? Should we support the projects that a few wealthy people are able to pay for or the projects that many poor people really need? There are distributive justice issues here. Also, how should we prioritize adaptations for humans vs. adaptations for ecosystems? Finally, what process should be used to make adaptation decisions? These questions and others are heavily debated among those involved in adaptation across all scales from local to global.
One final point to remember about impacts and adaptation is that they are occurring in the context of other changes to natural and social systems. In other words, climate change is not the only aspect of our world that is changing. There are also political, economic, technological, ecological, and other changes going on. As we prepare for the future impacts of climate change, it is important to remember that it will be the future world doing the adapting, not the present world. When we treat climate change as only one aspect of our world, we are more likely to be successful at adapting to future conditions in general, including conditions affected by climate change.