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Carbon dioxide (CO2) emitted to the atmosphere by human activities is being absorbed by the oceans, making them more acidic (lowering the pH the measure of acidity).

"What are the impacts of ocean acidification on key benthic (seabed) ecosystems, communities, habitats, species and their life cycles? The average acidity (pH) of the world's oceans has been stable for the last 25 million years. However, the oceans are now absorbing so much man made CO2 from the atmosphere that measurable changes in seawater pH and carbonate chemistry can be seen. It is predicted that this could affect the basic biological functions of many marine organisms. This in turn could have implications for the survival of populations and communities, as well as the maintenance of biodiversity and ecosystem function. In the seas around the UK, the habitats that make up the seafloor, along with the animals associated with them, play a crucial role in maintaining a healthy and productive marine ecosystem. This is important considering 40% of the world's population lives within 100km of the coast and many of these people depend on coastal systems for food, economic prosperity and well-being. Given that coastal habitats also harbour incredibly high levels of biodiversity, any environmental change that affects these important ecosystems could have substantial environmental and economical impacts. During several recent international meetings scientific experts have concluded that new research is urgently needed. In particular we need long-term studies that determine: which organisms are likely to be tolerant to high CO2 and which are vulnerable; whether organisms will have time to adapt or acclimatise to this rapid environmental change; and how the interactions between individuals that determine ecosystem structure will be affected. This current lack of understanding is a major problem as ocean acidification is a rapidly evolving management issue and, with an insufficient knowledge base, policy makers and managers are struggling to formulate effective strategies to sustain and protect the marine environment in the face of ocean acidification."

How is global temperature regulated? An experimental representation - Simple experiments to help pupils understand how different parameters regulate temperature at the Earth's surface. Interaction at the Air-Water Interface, part 1 - A very simple experiment to demonstrate gas exchange and equilibration at the boundary layer between air and water. Pupils will also observe acidification of water due to CO2 introduced directly in the water. Interaction at the Air-Water Interface, part 2 - A second set of experiment to demonstrate gas exchange and equilibration at the boundary layer between air and water. Pupils observe a high atmospheric CO2 concentration will produce water acidification. Uptake of Carbon Dioxide from the Water by Plants - The following experiments will demonstrate the role of plants in mitigating the acidification caused when CO2 is dissolved in water. Carbon Dioxide Fertilization of Marine Microalgae (Dunalliela sp.) Cultures: Marine microalgae in different atmospheric CO2 concentration - An experiment designed to illustrate the impact of carbon dioxide on microalgal growth in the aquatic environment. Introduction to the principles of climate modelling - Working with real data in spreadsheets to create a climate model, students discover the global carbon budget and make their own predictions for the next century. Global carbon budget between 1958 and 2007 - Working with real global carbon budget data, students produce graphs to find the best representation of the data to make predictions about human CO2 emissions for the next century. This activity is also a nice application of percentages. Estimation of natural carbon sinks - Working with real global carbon budget data, students estimate how much of the CO2 emitted into the atmosphere as a result of human activities is absorbed naturally each year. How does temperature affect the solubility of CO2 en the water? - The following experiments will explore effects of water temperature on sol

The term ocean acidification is used to describe the ongoing decrease in ocean pH caused by human CO2 emissions, such as the burning of fossil fuels. It is the little known consequence of living in a high CO2 world, dubbed at the 2009 United Nations Climate Change Conference (COP15) as the "evil twin of climate change". The oceans currently absorb approximately half of the CO2 produced by burning fossil fuel; put simply, climate change would be far worse if it were not for the oceans. However, there is a cost to the oceans - when CO2 dissolves in seawater it forms carbonic acid and as more CO2 is taken up by the oceans surface, the pH decreases, moving towards a less alkaline and therefore more acidic state. Already ocean pH has decreased by about 30% and if we continue emitting CO2 at the same rate by 2100 ocean acidity will increase by about 150%, a rate that has not been experienced for at least 400,000 years. Such a monumental alteration in basic ocean chemistry is likely to have wide implications for ocean life, especially for those organisms that require calcium carbonate to build shells or skeletons. Ocean acidification is a relatively new field of research, with most of the studies having been conducted over the last decade. While it is gaining some attention among policy makers, international leaders and the media, scientists find there is still a lack of understanding.