Ecological response to climate change

1. Ecological response to climate change Lilian Busse Scripps Institution of Oceanography ESP seminar June 9, 2006

2. Outline • Introduction into the climate-ocean-biology relationship • Presentation of some recent studies on the biological response to climate change • Conclusions • Concerns and uncertainties

3. What are the uncertainties in climate-ocean-biology relationship? • Great uncertainty how variations in the atmosphere gets translated into variations into the ocean or land and its populations • How will the climate change? • How will the biology react (on taxon level, on population level, ability to recover, thresholds)? • Are there other hypotheses to explain biological changes: habitat changes, pollution, El Nino etc.?

4. The ocean is warming… McGowan et al.

5. …SIO is a good proxy for overall changes… (McGowan et al. 1995)

6. And the possible responses of biology…

8. Recent studies: North Pacific and North Atlantic, increased temperatures: • Zooplankton-CalCOFI study • Food web studies North Atlantic • Foraminifera sediment study Entire ocean ecosystem, increased CO2: • Ocean acidification

9. Climate change Impact on plankton Impact on fish/fisheries Economic implications Impact on food supply for humans Plankton of the ocean

10. Zooplankton-CalCOFI study • Roemmich & McGowan 1995 – 43 years time series from CalCOFI (1951-1993) • Results: Decline of zooplankton by 80%, affects the foodweb (food for fish and birds) • Link to climate change: sea surface heated  T difference across thermocline increases  increase of stratification  less upwelling of nutrient rich water, less nutrients, less phytoplankton  less zooplankton • Conclusion: More climate change  massive biological impacts?

11. (Roemmich & McGowan 1995)

12. (Roemmich & McGowan 1995)

13. Planktonic food webs in the North Atlantic • Richardson and Schoemann 2004, Continuous Plankton Recorder, 1958-2002, North Atlantic, decadal and ocean basin scale • Results: Phytoplankton becomes more abundant when cooler regions warmed, because of higher metabolic rates BUT: when warm regions become warmer, phytoplankton becomes less abundant • Link to climate change: increased heating can enhance existing stratification, and therefore reduce nutrients to phytoplankton (in cooler water, enough turbulence, enough nutrients) • Conclusion: Effects on plankton will affect oxygen production, carbon sequestering, and biogeochemical cycling. It will also effect fisheries.

14. (McGowan et al.)

15. Planktonic food webs in the North Atlantic • Richardson and Edwards, 2004, marine pelagic phenology (study of annually recurring life cycle events) • Results: since 1987 – blooms are not synchronized anymore, phytoplankton 3 weeks earlier, zooplankton only 10 days earlier • Link to climate change: Shifts have occurred with increase in SST, physiological developments stimulated by higher temperature • Conclusions: Impacts on ecosystem functioning and higher trophic levels (e.g. fish) possible

16. Edwards and Richardson (2004)

17. Sediment Study • Field et al. 2006, foraminifera and ocean warming, 1,400 year time series, Santa Barbara Channel • Results: Foraminifera were strongly affected by global warming, increase of abundance of tropical and subtropical species, decrease of subpolar species • Link to climate change: tropical and subtropical speciesprefer higher SST, and deeper thermoclines • Conclusions: lower trophic levels in the CA currents is affected by 20th century warming

18. (Field et al. 2006)

19. Ocean acidification • There are 3 mineral forms of calcium carbonate: • Calcite • Aragonite • Magnesium calcite • Aragonite and Magnesium calcite more soluble than calcite • Cool water and deep waters are usually undersaturated with calcite and aragonite • Warmer shallower water is oversaturated with calcite and aragonite (Doney, 2006)

20. Ocean acidification • Doney, S.C. 2006, measurements of carbon in the ocean from 1989 and 2005, South Atlantic to Equator • Results: pH 0.1 lower that pre-industrial times (predicted 0.3 less on 2100), some marine life has less calcium carbonate to build their shells • Link to climate change: 1/3 of the CO2 released by fossil fuels ends up in the ocean • Conclusion: coccolithophorids, foraminifera, snails, and corals – they move, they disappear?; cold water less saturated, polar regions suffer first acidification

21. The future of Aragonite (Doney, 2006)

22. Conclusions • Presented studies show that climate change has an effects on the marine organisms, populations, and food web in the pelagic ecosystem • Marine food webs are complicated and are hard to untangle

23. Concerns and uncertainties • “Changes in the abundance and distribution of species of are not due to global change but due to land use changes and by natural fluctuations” → this statement ignores systematic trends we see across all ecosystems • Statistical, model, and fundamental uncertainty → Careful science can reduce but not eliminate uncertainties → Lack of full scientific certainty is not a reason for delaying immediate response • Length of time series- many time series are too short to detect full interdecadal cycles, spatial coverage of most studies is restricted to point sampling, diff. methods makes is difficult to combined multiple datasets- consistency across scales and systems means we should abide by the precautionary principle

24. References • Doney, S.C. 2006: The dangers of ocean acidification. Scientific American, March 2006, 1-9. • Edwards, M. & Richardson, A.J. 2004: Impact of climate change on marine pelagic phenology and trophic mismatch. Nature 430, 881-884. • Field, D.B., Baumgartner, T.R., Charles, C.D., Ferreira-Bartrina, V., Ohman, M.D. 2006: Planktonic Foraminifera of the California Current refeldt 20th-Century warming. Science 311, 63-66. • Richardson, A.J. & Schoeman, D.S. 2004: Climate impact on Plankton Ecosystems in the North East Atlantic. Science 305, 1609-1612. • Roemmich, D. & McGowan, J. 2003: Climatic Warming and the Decline of Zooplankton in the California Current. Science 267, 1324-1326.