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