Temperature and photoperiod play important roles in determining the timing of plant and animal life cycles. As the global climate becomes warmer, species are stressed by temperature, water, and food extremes.
In the upcoming Global Climate Change and Action section, you will learn how the U.S. Environmental Protection Agency is collaborating with Indigenous People to learn more about local changes in the relationship between climate and plant pollination.
In Northern Europe, Russia, and North America, for example, many plants now start “greening up” in spring a few days earlier than in the past in response to the warmer climate (Figure 20). However, in regions that occur further away from the equator, such as in Scandinavian countries at 60oN-70oN, the temperatures may warm earlier in spring, yet the seasonal photoperiod will not change. Therefore, temperature and photoperiod become asynchronous, occurring at different times. This timing mismatch affects crop pollination since the flowering of plants (which depends on the photoperiod) and the arrival of pollinators such as bees (which is dependent on the temperature) occur at different times. Decrease in crop pollination results in a marked reduction of food supply.
In addition, major changes in rain and snow deposits will greatly affect wildlife and crop success. As land surface temperatures rise, the land dries more rapidly and becomes more threatened by drought. At the same time, as temperature increases, the amount of moisture that the air can hold increases exponentially. This heightens precipitation intensity. Warmer climate thus creates both droughts and floods at different times, which affect the whole biosphere.
As noted above, oceanic microscopic organisms are threatened by the ocean acidification which is caused by increasing carbon dioxide levels in the atmosphere due to fossil fuel emissions. Many of these marine organisms build their protective external “shells” out of calcium carbonate (CaCO3), which easily dissolves in acidic water, putting an enormous stress on these tiny organisms (Figure 21). Since these microscopic organisms comprise the bottom of the food chain, the stress put on them by ocean acidification has cascading impacts up the entire chain to the top predators. Experiments suggest that coral reefs, mollusks, and sea urchins are particularly vulnerable to acidification. Additionally, reproduction of diatoms, a major group of algae and a primary producer of ocean biomass and atmospheric oxygen, is negatively affected.
Coral reefs are among the most biologically diverse communities of life on the planet. They are threatened not only by ocean acidification, but also by planetary warming which causes the corals to expel their endosymbionts or zooxanthellae, resulting in a white, bleached appearance. This can lead to the loss of a coral reef that would otherwise serve as a habitat for a rich diversity of coral reef fishes, and serve to protect many coastal island areas from storm surges.
Questions to Consider
Keep a record of the food items you eat every day at your main meal. Go to the Union of Concerned Scientists Climate Hot Map and see what impact global climate change may have on your food. How many of these food items could you afford to lose before your health would be at risk? What would you do to replace the food items of your main meal that could be lost to global climate change?
Science has advanced our understanding of global climate change. We understand what drives climate change and we understand the severe impacts climate change is having on environmental processes and human communities. However, as Dale Jamieson states:
. . . the problem we face is not a purely scientific problem that can be solved by the accumulation of scientific information. Science has alerted us to the problem, but the problem also concerns our values. It is about how we ought to live, and how human beings ought to relate to each other and to the rest of nature. These are problems of ethics . . . 1
It is to these problems that we now turn.