Oceans account for 99% of the living space and the majority of biodiversity on Earth. Though the oceans are vast, human mediated changes such as increased greenhouse gasses, pollution, and overfishing are changing the chemistry of the oceans and wreaking havoc on marine ecosystems. Only recently have we begun to understand the causes and implications of these changes, and it has quickly become apparent that immediate action is required to prevent catastrophic losses. "Seasick" is a timely and alarming summary of the oceans' human induced perils, which are being accelerated by global population growth and industrialization. In fact, this book was published in 2009, before the BP oil spill in the Gulf of Mexico directed the world's attention toward some of these problems. Author Alanna Mitchell is not a scientist, but after working with scientists all over the world, she has successfully channeled stories from seemingly disparate scientific fields into a coherent and powerful read. She explains how rising levels of atmospheric carbon dioxide and other anthropogenic inputs are causing rising temperatures, decreasing pH, changes in salinity, and harmful pollution in the seas. The extent of these problems is largely unknown, but the current effects and predictions are grim. Because the oceans serve as a conveyor belt for nutrient and temperature dispersion of the earth, many organisms, especially humans, interact with and depend upon the oceans in unnoticed, but intimate ways. Frighteningly, ocean temperatures change more slowly than land and air temperatures. It is predicted that even if carbon emissions and atmospheric temperatures leveled off today, ocean temperatures would continue to increase for the next thirty years. These unprecedented changes are abrupt and massive. Ocean temperatures have risen by 0.5 C thus far, and are predicted to increase another 2.5 C in next 100 years, resulting in hurricanes of unprecedented frequency and intensity. Most scientific models predict disaster for ocean life if no action is taken between 2015 and 2030. It is obvious that if we don't act soon, the surviving species will be forced to live in very different conditions than those they have evolved to survive in. In this book, Mitchell barely leaves herself any text to address the more direct human implications such as rising sea levels, losses of potential medicines due to extinction, and developing conflict over ocean resources. However, these more obvious consequences will probably be necessary to persuade governments and citizens to action. Because these consequences are less imminent than losses of biodiversity, I fear our actions will be too late.
Mitchell closes with an optimistic view of humanity and hope for the future. Since an understanding of the science and logic behind the oceans problems are now salient, she calls for a shift in our thinking, away from despair, towards wisdom and hope. She concludes the book with a simple statement, "If you believe that this matters and that something can be done, then the rest of the story reads that the time to act is right now." (135) I only wish she had been more explicit about actions her readers might take to achieve this.