As a result, projections of total future fishery yields under different climate change scenarios only show a moderate decrease of around 4% (~3.4 million tonnes) per degree Celsius warming. Mobile species, such as fish, may respond to climate change by moving to more favorable regions, with populations shifting poleward or to deeper water, to find their preferred range of water temperatures or oxygen levels. Although these cold water corals are not at risk from bleaching, due to their cooler environment, they may weaken or dissolve under ocean acidification, and other ocean changes. Coral habitats can also occur in deeper waters and cooler seas, and more research is needed to understand impacts in these reefs. Whilst some coral species are more resilient than others, and impacts vary between regions, further reef degradation due to future climate change now seems inevitable, with serious consequences for other marine and coastal ecosystems, like loss of coastal protection for many islands and low-lying areas and loss of the high biodiversity these reefs host. Other impacts of climate change include SLR, acidification and reef erosion. After mass coral mortalities due to bleaching, reef recovery typically takes at least 10–15 years. Such conditions occurred in many tropical seas between 20 and resulted in extensive coral bleaching, when the coral animal hosts ejected the algal partners upon which they depend. They are particularly vulnerable, since they can suffer high mortalities when water temperatures persist above a threshold of between 1 ° C–2 ° C above the normal range. Warm water coral reefs host a wide variety of marine life and are very important for tropical fisheries and other marine and human systems. The consequences for human society can be serious unless sufficient action is taken to constrain future climate change. Whilst these stressors and their combined effects are likely to be harmful to almost all marine organisms, food-webs and ecosystems, some are at greater risk (FAQ5.1, Figure 1). Non-climatic effects of human activities are also ubiquitous, including over-fishing and pollution. Seawater contains more dissolved carbon dioxide, causing ocean acidification. Due to closely linked changes in seawater chemistry, less oxygen remains available (in a process called ocean deoxygenation). In others, particularly in near-surface waters, warming has already had dramatic impacts on marine animals, plants and microbes. In many places, that increase may be barely measurable. Life in most of the global ocean, from pole to pole and from sea surface to the abyssal depths, is already experiencing higher temperatures due to human-driven climate change. The risk posed by climate change can be reduced by limiting global warming to no more than 1.5☌. Serena Moseman-Valtierra (United States)įAQ5.1: How is life in the sea affected by climate change?Ĭlimate change poses a serious threat to life in our seas, including coral reefs and fisheries, with impacts on marine ecosystems, economies and societies, especially those most dependent upon natural resources.Charlotte Laüfkotter (Switzerland, Germany).Lester Kwiatkowski (France, United Kingdom).Thomas Browning (Germany, United Kingdom).
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