Thresholds/tipping points/regime shifts/forecasting extreme events

Transcription

1 Thresholds/tipping points/regime shifts/forecasting extreme events Francisco Chavez Monterey Bay Aquarium Research Institute Ocean Biology Observatories Mestre, Italy September 2009

2 Tipping points/abrupt changes Typically used to describe changes associated with glacial/interglacial transitions Appears as if changes are larger at lower frequencies; duration over intensity? Glacial/interglacial, Little Ice Age, El Viejo/La Vieja (~PDO), El Niño All associated with changes in climate?

3 Rapid changes during the last glacial period

4 Physics vs. Biology Do biological systems respond in nonlinear ways to physical forcing? Amplify responses? Are biological systems the canary in the coal mine? Changes in climate versus changes in chemistry/biology (i.e. acidification); can one happen without the other?

5 What have learned from the recent (500 year) record? El Niño El Viejo/La Vieja/PDO, NAO, etc. Little Ice Age How they relate to climate and global change? Hint they tend to be globally coherent Changes not uniform: some go up others down; depends on where you are! What does this mean for Ocean Biology Observatories a global array?

6 Coastal upwelling ecosystems susceptible to changes in climate

7 Progress in Oceanography 2008

8 What is the unit of observation?

9 El Niño Associated with thermal dynamic changes at the basin (global) scale Redistribution of heat and mass from the western Pacifictowards the east started by westerly wind bursts Most notable effects are on eastern Pacific ecosystems

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11 Upwelling regions account for 1% of the ocean but ~50% of the global fish production, variability tied to large scale variations in thermocline topography

12 Change? Two Primary States SST SSH black line Variability

13 Pacific Decadal Oscillation

14 Regional Ocean Model Systems (ROMS)-CoSiNE CoSiNE: Carbon, Silicate, and Nitrogen Ecosystem (Chai and Chao) Eddy-Resolving Ocean Model at 12-km

15 Ecological Forecasting: Science at the leading and/or bleeding edge 9 month routine forecasts of 12.5 km basin scale solution Why Peru? 9 month forecast of chlorophyll

16 More fish (total and per unit primary production) than any other place in the world! Ryther would never have written classic 1969 paper had he gone to one of the other upwelling systems. Now know that anchoveta feeds primarily on zooplankton, another non-linearity at work..

17 50 year 50 km hindcast (ECWMF) simulation SST Data Model

18 Data Model SST Higher resolution blended winds Sea level

19 Carbon, Silicate, Nitrogen Ecosystem Model CoSiNE, Chai et al. 2002; Dugdale et al Fecal Pellet Sinking Micro- Zooplankton [Z1] Predation Detritus-N [DN] Mesozooplankton [Z2] Lost Chai et al., 1996 Fecal Pellet Grazing Excretion Detritus-Si [DSi] Sinking Small Phytoplankton [P1] Grazing NH 4 Uptake Ammonium [NH 4 ] N-Uptake Diatoms [P2] Sinking Iron Iron NO 3 Uptake Si Uptake Biological Uptake Nitrate [NO 3 ] Advaction & Mixing Silicate [Si(OH) 4 ] Air-Sea Exchange Total CO 2 [TCO 2 ] Physical Model

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21 Large regime shift documented in Monterey Bay, CA Cooler Poorer Lower oxygen

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23 The Length of the Record is Important Behrenfeld et al., Nature 2007

24 Strong physical biological coupling on global scales driven by ENSO/PDO dynamics

25 Temperature at 60 meters Monterey Bay Temperature at Depth Nitrate at 60 meters Monterey Bay Nitrate at Depth Local Ocean ecosystem responds to large scale forcing Monterey Bay Surface Chlorophyll

26 Results from a recent meeting in Peru (August) show strong correlations between the environment and living marine resources

27 Part of a larger scale phenomena

28 Change Variability Two Primary States Chavez et al. 2008

29 Once ever 3-8 years El Niño It is a familiar story Child La Niña El Viejo El Viejo Parent La Vieja La Vieja Once ever years 1900 to 2000

30 Sardine Landings Japan California Peru and Chile South Africa Alternations of anchovies and sardines

31 Oxygen When will El Viejo return and what will be the effects of global change?

32 Not simply a function of temperature (or nutrients?)

33 Field et al. Is this shift bigger than the previous 20 th century ones?

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35 Centennial-scale changes and the oxygen story Export production EUC ventilates CUC exports low oxygen Oxygen at 150 m Gutierrez et al., Biogeosciences

36 Fish Scale Record from a core off Peru Little Ice Age

37 Summary, during Little Ice Age ocean off Peru high oxygen (low fish), low oxygen (high fish) after

38 Driven by southward migration of InterTropical Convergenze Zone (ITCZ) during Little Ice Age

39 The low oxygen expanded southward in to Chile, what about the recent record (~50 years) California Peru

40 Long-Term ( ) Trend in California Dissolved Oxygen -2.1 mol/kg/y decrease in oxygen at 50 m Z mean = -41 m Z max = -92 m Shoaling oxycline Bograd et al. in press, with Chavez Monterey oxygen on 26.8

41 In situ oceanographic data off Peru shows that ocean losing nitrate (oxygen is zero so nitrate electron donor) and increasing productivity

42 It appears as if the tropical (eastern Pacific) low oxygen regions reformed after the Little Ice Age and continue to expand (and increase in productivity?) today Are there biological indicators of this expansion?

43 Catchability (F/f) 14 S Latitude 3S The Hake off Peru has retreated and gotten more concentrated Consistent with a decrease in ventilation by the Equatorial Undercurrent Hake inecuador Merluza durante La Niña (1996) Index of hake concentración

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45 A large Humboldt squid caught offshore from Sitka in October 2004 is among numerous sightings of a species seen for the first time in waters of the Far North Tons JUMBO FLYING SQUID LANDINGS Years PERU MEXICO

46 Summary of oxygen story Low oxygen in eastern Pacific as we know today reformed after the Little Ice Age Expansion continues today? Low oxygen=low ph Anthropogenic influences pushing in the same direction (i.e. warming, stratification reducing ventilation, CO2 absorption < ph) Peru and Chile, a window into the future?

47 What about global warming?

48 The northwest African margin is a coastal upwelling system. Sea surface temperature (SST) records from Moroccan sediment cores, extending back 2500 years, reveal anomalous and unprecedented cooling during the 20th century, which is consistent with increased upwelling. Upwelling-driven SSTs vary out of phase with millennialscale changes in Northern Hemisphere temperature anomalies (NHTAs) and show relatively warm conditions during the Little Ice Age and relatively cool conditions during the Medieval Warm Period. These results suggest that coastal upwelling may continue to intensify as global warming and atmospheric CO2 levels increase. McGregor, Dima, Fischer, Mulitza Science, 2/2/2007

49 El Niño Same thing during El Viejo i.e. warmer coastal upwelling and warmer world

50 A developing Paradox Observations from the modern record show that the entire globe warms during El Niño and El Viejo and in coastal upwelling systems (at least in the Pacific) temperature goes up and ecosystem productivity goes down. The opposite seems to happen on longer time scales. During the Little Ice Age when the world as a whole cooled the coastal upwelling system off NW Africa warmed and the coast of Peru became less productive. Then when the world warmed the coastal upwelling ecosystems became more productive. We must be looking at very different mechanisms.. Will there be more (pelagic) fish in a warmer (and lower

51 We can measure ocean acidification in Monterey Bay!!

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54 What does this mean for Ocean Biology Observatories Need many cheap globally a few (10?) regional globally distributed Given costs should pick locations carefully Need to cover full ecosystem (from physics to chemistry to microbes to top predators Need to develop standard methods/areas Many already exist-need to augment these and add others now! Comparative approach: planned for Eastern boundaries - SOLAS

55 Two possible approaches Use the point approach and attempt to develop a single standard system and make the system available globally Determine critical and sensitive areas, determine the area for the OBO, design each based on its own set of criteria and use standard methods Stratified OBOs: point for T,S,N,P; regional for migratory populations