Query: ‘But even if an organism isn’t directly harmed by acidification it may be affected indirectly through changes in its habitat or changes in the food web.’

Relevant passages:
Ocean acidification <=SEP=> Ocean acidification is the ongoing decrease in the pH of the Earth 's oceans , caused by the uptake of carbon dioxide from the atmosphere . Seawater is slightly basic ( meaning pH > 7 ) , and the process in question is a shift towards pH-neutral conditions rather than a transition to acidic conditions ( pH < 7 ) . Ocean alkalinity is not changed by the process , or may increase over long time periods due to carbonate dissolution . An estimated 30 -- 40 % of the carbon dioxide from human activity released into the atmosphere dissolves into oceans , rivers and lakes . To achieve chemical equilibrium , some of it reacts with the water to form carbonic acid . Some of these extra carbonic acid molecules react with a water molecule to give a bicarbonate ion and a hydronium ion , thus increasing ocean acidity ( H + ion concentration ) . Between 1751 and 1996 surface ocean pH is estimated to have decreased from approximately 8.25 to 8.14 , representing an increase of almost 35 % in H + ion concentration in the world 's oceans . Earth System Models project that within the last decade ocean acidity exceeded historical analogues and in combination with other ocean biogeochemical changes could undermine the functioning of marine ecosystems and disrupt the provision of many goods and services associated with the ocean .   Increasing acidity is thought to have a range of potentially harmful consequences for marine organisms , such as depressing metabolic rates and immune responses in some organisms , and causing coral bleaching . By increasing the presence of free hydrogen ions , each molecule of carbonic acid that forms in the oceans ultimately results in the conversion of two carbonate ions into bicarbonate ions . This net decrease in the amount of carbonate ions available makes it more difficult for marine calcifying organisms , such as coral and some plankton , to form biogenic calcium carbonate , and such structures become vulnerable to dissolution . Ongoing acidification of the oceans threatens food chains connected with the oceans . As members of the InterAcademy Panel , 105 science academies have issued a statement on ocean acidification recommending that by 2050 , global emissions be reduced by at least 50 % compared to the 1990 level .   While ongoing ocean acidification is anthropogenic in origin , it has occurred previously in Earth 's history . The most notable example is the Paleocene-Eocene Thermal Maximum ( PETM ) , which occurred approximately 56 million years ago . For reasons that are currently uncertain , massive amounts of carbon entered the ocean and atmosphere , and led to the dissolution of carbonate sediments in all ocean basins .   Ocean acidification has been called the `` evil twin of global warming '' and `` the other problem '' .

Environmental impact of the coal industry <=SEP=> The environmental impact of the coal industry includes issues such as land use , waste management , water and air pollution , caused by the coal mining , processing and the use of its products . In addition to atmospheric pollution , coal burning produces hundreds of millions of tons of solid waste products annually , including fly ash , bottom ash , and flue-gas desulfurization sludge , that contain mercury , uranium , thorium , arsenic , and other heavy metals .   There are severe health effects caused by burning coal . According to a report by the World Health Organization in 2008 , coal particulates pollution are estimated to shorten approximately 1,000,000 lives annually worldwide . A 2004 study commissioned by environmental groups , but contested by the US EPA , concluded that coal burning costs 24,000 lives a year in the United States .   Historically , coal mining has been a very dangerous activity and the list of historical coal mining disasters is a long one . Underground mining hazards include suffocation , gas poisoning , roof collapse and gas explosions . Open cut hazards are principally mine wall failures and vehicle collisions . In the United States , an average of 26 coal miners per year died in the decade 2005-2014 .

Human impact on marine life <=SEP=> Human activities affect marine life and marine habitats through overfishing, habitat loss, the introduction of invasive species, ocean pollution, ocean acidification and ocean warming. These impact marine ecosystems and food webs and may result in consequences as yet unrecognised for the biodiversity and continuation of marine life forms.According to the IPCC (2019), since 1950 "many marine species across various groups have undergone shifts in geographical range and seasonal activities in response to ocean warming, sea ice change and biogeochemical changes, such as oxygen loss, to their habitats."It has been estimated only 13% of the ocean area remains as wilderness, mostly in open ocean areas rather than along the coast.