Interannual Time Scales: ENSO Decadal Time Scales: Basin Wide Variability (e.g. Pacific Decadal Oscillation, North Atlantic Oscillation) Longer Time Scales: Warming trend Marine Ecosystems and Climate Variability

SST Anomalies – Jan 1998 SST Anomalies – Dec 1999 A B ºCºC Pt. 1 Pt. 2 Pt. 3 y x ENSO Warm Phase Cold Phase Less upwelling Less primary production Less CO2 flux out of the ocean More upwelling More primary production More CO2 flux out of the ocean

Interannual Time Scales: ENSO Decadal Time Scales: Basin Wide Variability (e.g. Pacific Decadal Oscillation, North Atlantic Oscillation) Longer Time Scales: Warming trend Marine Ecosystems and Climate Variability

PACIFIC OCEAN Marine Ecosystems and Climate Variability Decadal scale variations

(source: Checkley et al., 2000) Sardine Eggs Changes in Fish abundance is driven by the variability of hydrographic conditions Point Conception

Regional indices of Climate variability PACIFIC OCEAN

Most of the regional indices reflect large-scale climate variations in the North Pacific they can be summarized Pacific Decadal Oscillation Index

CurrentsSST

January Mean Sea Level Pressure

Negative Phase Positive Phase Mean Sea Level Pressure

Anomaly PDO Negative PhaseMean Sea Level Pressure Anomaly PDO Positive Phase

Anomaly PDO Negative Phase Anomaly PDO Positive Phase SST Anomalies

Pacific Decadal Oscillation

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Large-scale indices of Climate variability PACIFIC OCEAN..and biology 1976 Regime Shift ?

WARM PHASE of PDO

COLD PHASE of PDO

Transitions in the Ecosystem may by nonlinear and sudden. There could be predictive skill (in terms of climate change) in monitoring closely the ecosystem

Observations along the California Coast

Zoo- plankton Phytoplankton Abundance Population Dynamics

A simple Ecosystem model Phyto Detritus NO 3 NH 4 Zoo Physical Environment

The seasonal cycle of the simple model

Increasing nutrient supply Seasonal cycles

A simple Ecosystem model Phyto Detritus NO 3 NH 4 Zoo Physical Environment Fish and Higher Trophic Levels HUMANS

Historical Overfishing and the Recent Collapse of Coastal Ecosystems Jackson et al., Science, Vol 293, Issue 5530, , 27 July 2001 KELP FOREST

Historical Overfishing and the Recent Collapse of Coastal Ecosystems Jackson et al., Science, Vol 293, Issue 5530, , 27 July 2001 and more comlpex… Coral Reefs

A simple Ecosystem model Phyto Detritus NO 3 NH 4 Zoo Physical Environment Fish and Higher Trophic Levels HUMANS GLOBAL WARMING and Carbon Cycle

End of lecture

Short Climate Variability occurs in all oceans Aleutian Low

What is the North Atlantic Oscillation ? " A sea saw of atmospheric mass which alternates between the polar and subtropical regions. " Changes in the mass and pressure fields lead to variability in the strength and pathway of storm systems crossing the Atlantic from the US East coast to Europe. " The NAO is most noticeable during the winter season (November - April) with maximum amplitude and persistence in the Atlantic sector. Martin Visbeck24 December, 2015

The North Atlantic Oscillation Index " An Index can be constructed that represents the phase of the NAO. Most commonly the NAO index is based on the surface pressure (SLP) difference between the Subtropical (Azores) high and the Subpolar (Island) low. " Very often the pressure readings from two stations one on Iceland and the other either the Azores, Lisbon or Gibraltar are used to construct the NAO index. The twice daily reading are averaged from November through March and the difference in then the winter NAO index. Martin Visbeck24 December, 2015

The North Atlantic Oscillation Index " The NAO index shows large variations from year to year. This interannual signal was especially strong during the end of the 19 th century. " Sometimes the NAO index stays in one phase phase for several years in a row. This decadal variability was quite strong at the beginning and end of the 20 th century. " One might also interpret the recent 30 years as a trend in the NAO index possibly linked to "global warming". Martin Visbeck24 December, 2015

The positive NAO index phase " The positive NAO index phase shows a stronger than usual subtropical high pressure center and a deep than normal Icelandic low. " The increased pressure difference results in more and stronger winter storms crossing the Atlantic Ocean on a more northerly track. " This results in warm and wet winters in Europe and in cold and dry winters in northern Canada and Greenland. " The eastern US experiences mild and wet winter conditions. Martin Visbeck24 December, 2015

The negative NAO index phase " The negative NAO index phase shows a weak subtropical high and weak Icelandic low. " The reduced pressure gradient results in fewer and weaker winter storms crossing on a more west-east pathway. " They bring moist air into the Mediterranean and cold weather to northern Europe. " The US east cost experiences more cold air outbreaks and hence snowy winter conditions. " Greenland, however, will have milder winter temperatures. Martin Visbeck24 December, 2015

North Altantic Oscillation

Reading/Homework assignment:

What is interesting about the relationship between Climate and Ocean Biology? Examples: Fisheries and food Global Warming problem Preservation of species

An example 1) The Pacific Decadal Oscillation and ecosystem responses 2) Understanding the ecosystem response with models 3) The North Atlantic Oscillation and ecosystem responses

Nitrate Concentration Abundance Reached at equilibrium

Abundance Days Oscillation begin Oscillation stop hysteresis

Limit cycles The ecosystem may become Very unpredictable