Arctic Sea Ice

The Arctic Ocean is an ecologically and climatologically important region, and it is warming at a rate two times faster than the global average. Even more troubling, global climate models using the IPCC business as usual scenario predict an increase in average Arctic temperatures of 7°C (12.6°F) by 2100. The rapid warming of the last 33 years has already impacted Arctic sea ice cover, with 2012 representing a new minimum in ice cover and an 80% loss in summer sea ice volume. Furthermore, diminishing sea ice plays a central role in amplifying Arctic warming. This is a positive feedback loop: increasing temperatures lead to a loss of sea ice, which in turn amplifies warming, speeding loss of even more ice. The Arctic has many such positive feedbacks and tipping points, which leave it extremely sensitive to global climate change.

Artisanal Fisheries Impacts

From a WorldFish Center study: "Vulnerability of national economies to potential climate change impacts on fisheries... under IPCC scenario B2." (Allison et al. 2009)

Small-scale fisheries are critically important for food, income, and well-being for 100s of millions of people around the world. They are a vitally important interface between people and marine or aquatic resources, depending heavily on the health and resilience of these marine and aquatic ecosystems.

Climate change threatens these fisheries and the many people who depend upon them. Sea level rise, increased Extreme weather events, decreased predictability in seasons, and oceanographic changes (such as changes in salinity and water temperature) impact marine and aquatic ecosystems and fish stocks, the ability for fishers to go fishing, and the infrastructure of coastal and riverine communities, and even impact alternative sources of food and income. Fishing communities around the world are already feeling many of these impacts.

Impacts Ecosystems & Fish Fishing Practices Communities
Sea Level Rise
  • Loss of coastal habitat
  • Saltwater intrusion in freshwater habitat
  • Lower yield from coastal and freshwater fisheries
  • Loss of landing sites
  • Saltwater intrusion in agricultural fields
Changing Weather Patterns
  • Extreme weather events
  • Changes in seasonality
  • Rainfall changes
  • Change in productivity
  • Change in abundance and distribution of plankton & fish
  • Increased sedimentation on coral reefs & seagrass beds
  • Decreased good-weather days for fishing
  • Unpredictable fishing seasons
  • Lower yield from coastal and freshwater fisheries
  • Flooding or drought
  • Impacts on agriculture
  • Increased coastal erosion
  • Catastrophic weather events (hurricanes, storms)
Ocean Changes
  • Sea surface temperature
  • Salinity
  • Ocean acidification
  • Change in nutrient availability
  • Change in abundance and distribution of plankton & fish
  • Negative impacts on calcifying organisms (e.g., corals)
  • Lower yield from coastal & open-water fisheries

Resilience and adaptation

To adapt to ongoing and future impacts of climate change, small-scale fishing communities will need strengthened infrastructure, increase resilience to unpredictable fishing seasons and extreme weather events, and more secure access to coastal resources and to alternative livelihoods. Reducing other impacts to coastal and freshwater ecosystems (e.g., pollution, habitat destruction) could increase the resilience of these resources to climate change effects. Input and assistance from provincial, national, and international institutions are necessary to mitigate climate change impacts on these fisheries and the well-being of the communities that depend upon them.


  • Allison, E.H., et al. 2009. Vulnerability of national economies to the impacts of climate change on fisheries. Fish and Fisheries.
  • Williams and Rota. 2010. Impact of climate change on fisheries and aquaculture in the developing world and opportunities for adaptation. International Fund for Agricultural Development.
  • FAO 2009. The State of the World Fisheries and Aquaculture 2008. FAO.

Created By: Whitty, T.S. 2014. Small-scale and Artisanal Fisheries Research Network, Center for Marine Biodiversity and Conservation.

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Ocean Acidification

What is Ocean Acidification?

Ocean acidification is the process of carbon dioxide (CO2) in the air being absorbed by the oceans and causing significant changes in seawater chemistry. Anthropogenic ocean acidification describes the uptake of excess human-produced CO2 by the oceans, a process that causes arise in seawater acidity.

Here are the basic facts about ocean acidification:

  • Since the beginning of the Industrial Revolution, the oceans have absorbed approximately a third of the carbon dioxide we have produced
  • This has caused an increase of 30% in surface ocean acidity.
  • If current carbon dioxide emissions continue at this rate, ocean acidity is expected to increase 100-150% percent more, relative to the beginning of the Industrial Revolution.
  • Anthropogenic ocean acidification is of great concern because, to our knowledge, it is at least 10 times faster than any natural acidification event in the past.

Ocean Deoxygenation

Why is Oxygen Important to Life in the Ocean?

Oxygen is necessary to support life on Earth. Oxygen makes up about 21% of the air we breathe and half of this oxygen is produced by phytoplankton in the ocean. All aerobic life requires oxygen to produce energy. In water, oxygen is found in a dissolved form and is much more limiting. For this reason, we measure dissolved oxygen in water not in % but in units of umol/kg. The highest concentrations of dissolved oxygen in the ocean are found within the surface mixed layer at concentrations of > 200 umol/kg. Below the surface mixed layer, oxygen concentrations are lower due to respiration by all of the trillions of organisms and bacteria that live in the water column.

What is Ocean Deoxygenation?

Ocean deoxygenation refers to the loss of oxygen from the oceans due to climate change (Keeling et al. 2010). Long-term ocean monitoring shows that oxygen concentrations in the ocean have declined during the 20th century, and the new IPCC 5th Assessment Report (AR5 WG1) predicts that they will decrease by 3-6% during the 21st century in response to surface warming. While 3-6% doesn’t seem like much, this decrease will be felt acutely in hypoxic and suboxic areas, where oxygen is already limiting. “Hypoxic” areas are defined as regions where oxygen limitation is detrimental to most organisms. This threshold differs across the world, but is usually defined as anything below 60 umol/kg. Hypoxic zones have oxygen concentrations 70-90% lower than the mean surface concentrations. “Suboxic” areas are areas where oxygen is so low (less than 5 umol/kg) that most life cannot be sustained and significant biogeochemical changes occur due to altered water chemistry. Suboxic zones have oxygen concentrations 98% lower than the mean surface concentrations. A recent study found that a 1°C warming throughout the upper ocean will result in the increase of hypoxic areas by 10% and a tripling of the volume of suboxic waters (Deutsch et al. 2011). To put this in context, a highly optimistic emissions scenario of atmospheric CO2 levels of 550 ppm by 2100 would lead to a 1.2°C warming of the upper ocean (Mora et al. 2013). Therefore, these declines in oxygen are changes we should be prepared to see.

Ocean Warming

Decades into the industrial revolution, the HMS Challenger Expedition sailed into the sea, looking for answers to questions that still intrigue oceanographers to this day. Little did these pioneers of ocean sciences know that their measurements will be used 140 years later by Scripps Oceanography Researcher Dean Roemmich to measure the human-induced warming of the world's oceans since the mid-1800's.

One of the most under-appreciated facts in climate change is the fate of the energy trapped by greenhouse gas emissions from human activities. Human activities are releasing nearly 10 Gegatons of Carbon (about 36 Billion tons of CO2) into the atmosphere every year, driving atmospheric CO2 concentrations to 400 parts per million (ppm) from their original preindustrial levels of 280 ppm. This increase in CO2 and other greenhouse gases concentrations traps additional energy in the earth's climate system. What happens to this "extra" energy (0.5-1 watt/m2) remains a mystery to many outside the field of climate and ocean sciences.

Contact Information

Ocean Scientists for Informed Policy
Scripps Institution of Oceanography
University of California, San Diego
9500 Gilman Drive
La Jolla, CA 92083-0202