The Effects of Global Warming on the Marine
Environment
How Global Warming Works• The mechanism for global warming
is the Greenhouse Effect• Greenhouse gases include carbon
dioxide (CO2), methane (CH4),
CFCs, nitrous oxide (N2O), ozone• Greenhouse gases prevent infrared
radiation from escaping to outerspace and it is converted to heat, thereby increasing atmospherictemperatures
How Global Warming Works
How GlobalWarming Works
• CO2 is the most importantgreenhouse gas
• CO2 is released from theburning of fossil fuels –coal, oil, natural gas
• CO2 is easily absorbed bythe oceans – up to a point- dissolves in water- used in photosynthesis
How Global Warming Works
• CO2 levels have increased 30% sincebefore the Industrial Revolution
Major Impacts
• Changes to ocean temperature• Changes to ocean currents• Localized salinity changes• Sea level rise• Ocean acidification• Increase in severe weather events• Invasive Species, Changes to Habitats and
Food Supply
Impacts: Changes to Ocean Temperature
• If atmosphere warms, ocean warms• Most marine organisms spawn (reproduce) in response
to temperature cues – will reproduce at wrongtime
Impacts: Changes to Ocean Temperature
• Phytoplankton bloom in response to light and temperature cues
• Changes will impactfood webs
Impacts: Changes to Ocean Temperature
• Migrations are in response to temperature• May impact fisheries
Impacts: Changes to Ocean Temperature
coral bleaching• as reefs become
warmer, corals expel symbiotic algae and become “bleached”
• leads to loss of habitat and food for reef-dependant species
Impacts: Changes to Ocean Temperature
hypoxia – low levels of dissolved oxygen– warmer water
temperatures increase the chances that available oxygen will be used up more rapidly by existing organisms
Major Impacts
• Changes to ocean temperature• Changes to ocean currents• Localized salinity changes• Sea level rise• Ocean acidification• Increase in severe weather events• Invasive Species, Changes to Habitats and
Food Supply
Impacts: Changes to Ocean Currents
• like a giant conveyor belt – carrying warm and cold water from shallow to deep and deep to shallow
• global warming may stop/change this flow
Impacts: Changes to Ocean Currents
• carry different temperature water• currents moderate coastal climate
ex: EnglandGulf Stream Current
Impacts: Changes to Ocean Currents
ocean currents:• transport planktonic (drifting)
organisms• distribute eggs and larvae• bring food and oxygen to
sessile organisms• remove wastes and pollutants
Major Impacts
• Changes to ocean temperature• Changes to ocean currents• Localized salinity changes• Sea level rise• Ocean acidification• Increase in severe weather events• Invasive Species, Changes to Habitats and
Food Supply
Impacts: Localized Salinity Changes
• salinity – measure of dissolved solidsin water
• organisms have specific salinity ranges inwhich they can survive
Impacts: Localized Salinity Changes
• glaciers are fresh water• melting will locally decrease salinity
and impact organisms• freshwater can also change deep sea
circulation
Major Impacts
• Changes to ocean temperature• Changes to ocean currents• Localized salinity changes• Sea level rise• Ocean acidification• Increase in severe weather events• Invasive Species, Changes to Habitats and
Food Supply
Impacts: Sea Level Rise
• water in glaciers is on land • as glaciers melt, water is added to ocean• as water heats, it expands• both raise sea level world wide
Impacts: Sea Level Rise
• destroys coastal habitatsex: salt marshes, mangroves
• destroys humanproperty
• increased pollution• decreased freshwater
supplies
Major Impacts
• Changes to ocean temperature• Changes to ocean currents• Localized salinity changes• Sea level rise• Ocean acidification• Increase in severe weather events• Invasive Species, Changes to Habitats and
Food Supply
Impacts: Ocean Acidification
• CO2 absorbed by the ocean makes it more acidic
• can kill phytoplankton resulting in major food web effects
Impacts: Ocean Acidification
• calcium carbonate (CaCO3) shells dissolve or are harder to make – organisms cannot survive
• acidosis – build up of carbonic acid in organisms
Major Impacts• Changes to ocean temperature• Changes to ocean currents• Localized salinity changes• Sea level rise• Ocean acidification• Increase in severe weather events• Invasive Species, Changes to Habitats and
Food Supply
Impacts: Increase in Severe Weather Events
• hurricanes need warm water to form• warming of ocean waters may increase
the number of hurricanes or their intensity
Impacts: Increase in Severe Weather Events
• increased strength and number of hurricanes can lead to:
- habitat destruction- property destruction
Major Impacts• Changes to ocean temperature• Changes to ocean currents• Localized salinity changes• Sea level rise• Ocean acidification• Increase in severe weather events• Invasive Species, Changes to Habitats and
Food Supply
Impacts: Invasive Species, Changes to Habitats and Food Supply
invasive species – non-native species that adversely affect a habitat• warmer waters make it easier for invading
species to gain a foothold• can consume or outcompete native species
invasive algae covering coral reef
Impacts: Invasive Species, Changes to Habitats and Food Supply
• all impacts can result in the loss of coastal and marine habitat, disruption of the food web and loss of biodiversity