1. Earth’s Biosphere Interaction of physical processes in Earth’s climate system with biosphere Interaction of physical processes in Earth’s climate system with biosphere  Results from the movement of carbon

2. Carbon Cycle Carbon moves freely between reservoirs Carbon moves freely between reservoirs  Flux inversely related to reservoir size

3. Photosynthesis Sunlight, nutrients, H 2 O Sunlight, nutrients, H 2 O Transpiration in vascular plants Transpiration in vascular plants  Efficient transfer of H 2 O(v) to atmosphere Oxidation of C org Oxidation of C org  Burning  Decomposition

4. Terrestrial Photosynthesis CO 2 and sunlight plentiful CO 2 and sunlight plentiful H 2 0 and correct temperature for specific plants not always sufficient H 2 0 and correct temperature for specific plants not always sufficient Biomass and biome distribution controlled by rainfall and temperature Biomass and biome distribution controlled by rainfall and temperature

5. Local Influence on Precipitation Orographic precipitation influences distribution of biomass and biomes Orographic precipitation influences distribution of biomass and biomes Influences the distribution of precipitation Influences the distribution of precipitation

6. Marine Photosynthesis H 2 O, CO 2 and sunlight plentiful H 2 O, CO 2 and sunlight plentiful Nutrients low (N, P) Nutrients low (N, P) Nutrients extracted from surface water by phytoplankton Nutrients extracted from surface water by phytoplankton Nutrients returned by recycling Nutrients returned by recycling  Upper ocean (small)  Upwelling (high)  External inputs (rivers, winds)

7. Ocean Productivity Related to supply of nutrients Related to supply of nutrients Nutrient supply high in upwelling regions Nutrient supply high in upwelling regions  Equatorial upwelling  Coastal upwelling Southern Ocean Southern Ocean  Wind-driven mixing  Short growing season  Light limitation

8. Productivity – Climate Link “Biological Pump” – photosynthesis takes up CO 2 and nutrients, plants eaten by zooplankton, dead zooplankton or excreted matter sinks carrying carbon to sediments “Biological Pump” – photosynthesis takes up CO 2 and nutrients, plants eaten by zooplankton, dead zooplankton or excreted matter sinks carrying carbon to sediments

9. Export – Removal of Carbon For every 1000 carbon atoms taken up by phytoplankton For every 1000 carbon atoms taken up by phytoplankton 50-100 sink below 100 m 50-100 sink below 100 m 10 are exported to depths below 1 km 10 are exported to depths below 1 km  Stored for millennia 1 carbon atom is buried in deep sea sediments 1 carbon atom is buried in deep sea sediments  Sequestered for eons

10. HNLC Growth in regions limited by micronutrients (Fe) Growth in regions limited by micronutrients (Fe)  High nutrient low chlorophyll (N. Pacific, SO) Higher production linked with removal of CO 2 Higher production linked with removal of CO 2

11. Effect of Biosphere on Climate Changes in greenhouse gases (CO 2, CH 4 ) Changes in greenhouse gases (CO 2, CH 4 ) Slow transfer of CO 2 from rock reservoir Slow transfer of CO 2 from rock reservoir  Does not directly involve biosphere  10-100’s millions of years CO 2 exchange between shallow and deep ocean CO 2 exchange between shallow and deep ocean  10,000-100,000 year Rapid exchange between ocean, vegetation and atmosphere Rapid exchange between ocean, vegetation and atmosphere  Hundreds to few thousand years

12. Increases in Greenhouse Gases CO 2 increase anthropogenic and seasonal CO 2 increase anthropogenic and seasonal  Anthropogenic – burning fossil fuels and deforestation  Seasonal – uptake of CO 2 in N. hemisphere terrestrial vegetation Methane increase anthropogenic Methane increase anthropogenic  Rice patties, cows, swamps, termites, biomass burning, fossil fuels, domestic sewage

13. Climate Archives Four major archives of climate records Four major archives of climate records  Sediments  Ice  Corals  Trees Each archive has different time span, resolution and ease of dating Each archive has different time span, resolution and ease of dating

14. Understanding Climate Change Understanding present climate and predicting future climate change requires Understanding present climate and predicting future climate change requires  Theory  Empirical observations Study of climate change involves construction (or reconstruction) of time series of climate data Study of climate change involves construction (or reconstruction) of time series of climate data  How these climate data vary across time provides a measure (quantitative or qualitative) of climate change  Types of climate data include temperature, precipitation (rainfall), wind, humidity, evapotranspiration, pressure and solar irradiance

15. Contemporary & Past Climate Contemporary climate studies use empirically observed instrumental data Contemporary climate studies use empirically observed instrumental data  Temperature records available from central England beginning in the 17 th century  Period traditionally associated with instrumental records extends back to middle of the 19 th century Climate change from periods prior to the recording of instrumental data Climate change from periods prior to the recording of instrumental data  Must be reconstructed from indirect or proxy sources of information

16. Climate Construction from Instrumental Data Contemporary climate change studied by constructing records (daily, monthly and annual) which have been obtained with standard equipment Contemporary climate change studied by constructing records (daily, monthly and annual) which have been obtained with standard equipment  Temperature  Rainfall  Humidity  Wind

17. Paleoclimate Reconstructions Climate varies over different time scales and each periodicity is a manifestation of separate forcing mechanisms Climate varies over different time scales and each periodicity is a manifestation of separate forcing mechanisms Different components of the climate system change and respond to forcing factors at different rates Different components of the climate system change and respond to forcing factors at different rates To understand the role each component plays in the evolution of climate we must have a record longer than the time it takes for the component to undergo significant change To understand the role each component plays in the evolution of climate we must have a record longer than the time it takes for the component to undergo significant change

18. Paleoclimatology Study of climate change prior to the period of instrumental measurements Study of climate change prior to the period of instrumental measurements Instrumental records span only a fraction (<10 -7 ) of Earth's climatic history Instrumental records span only a fraction (<10 -7 ) of Earth's climatic history  Provide a inadequate perspective on climatic variation and the evolution of the climate today and in the future A longer perspective on climate variability can be obtained by the study of natural climate- dependent phenomena A longer perspective on climate variability can be obtained by the study of natural climate- dependent phenomena Such phenomena provide a proxy record of the climate Such phenomena provide a proxy record of the climate

19. Paleoclimate Proxy Records Many natural systems are dependent on climate Many natural systems are dependent on climate  It may be possible to derive paleoclimatic information from them By definition, such proxy records of climate all contain a climatic signal By definition, such proxy records of climate all contain a climatic signal  The signal may be weak and embedded in a great deal of (climatic) background noise  Proxy material acts as a filter, transforming climate conditions in the past into a relatively permanent record  Deciphering that record can often be complex

20. Proxy Data Proxy material can differ according to Proxy material can differ according to  Its spatial coverage  The period to which it pertains  Its ability to resolve events accurately in time For example For example  Ocean floor sediments, reveal information about long periods of climatic change and evolution (10 7 years), with low-frequency resolution (10 3 years)  Tree rings useful only during the last 10,000 years, but offer high frequency (annual) resolution The choice of proxy record (as with the choice of instrumental record) depends on physical mechanism under review The choice of proxy record (as with the choice of instrumental record) depends on physical mechanism under review

21. Factors to Consider When using proxy records to reconstruct paleoclimates one must consider When using proxy records to reconstruct paleoclimates one must consider  The continuity of the record  The accuracy to which it can be dated  Ocean sediments may be continuous for over 1 million years but are hard to date  Ice cores may be easier to date but can miss layers due to melting and wind erosion  Glacial deposits are highly episodic, providing evidence only of discrete events in the past Different proxy systems have different levels of inertia with respect to climate Different proxy systems have different levels of inertia with respect to climate  Some systems vary in phase with climate forcing  Some systems lag behind by as much as several centuries

22. Steps in Reconstructing Climate Paleoclimate reconstruction proceeds through a number of stages Paleoclimate reconstruction proceeds through a number of stages  The 1 st stage is proxy data collection, followed by initial analysis and measurement  This results in primary data  The 2 nd stage involves calibration of the data with modern climate records  The secondary data provide a record of past climatic variation  The 3 rd stage is the statistical analysis of this secondary data  The paleoclimatic record is statistically described and interpreted

23. Proxy Calibration The uniformitarian principle is typically assumed The uniformitarian principle is typically assumed  Contemporary climatic variations form a modern analog for paleoclimatic changes  However the possibility always exists that paleo-environmental conditions may not have modern analogs  The calibration may be only qualitative, involving subjective assessment, or it may be highly quantitative

24. Proxy Calibration: An Example Emiliania huxleyi is one of 5000 or so species of phytoplankton Emiliania huxleyi is one of 5000 or so species of phytoplankton Most abundant coccolithophore on a global basis, and is extremely widespread Most abundant coccolithophore on a global basis, and is extremely widespread  Occurs in all except the polar oceans Produces unique compounds Produces unique compounds  C 37 -C 39 di-, tri- and tetraunsaturated methyl and ethyl ketones

25. Emiliania huxleyi Blooms E. huxleyi can occur in massive blooms E. huxleyi can occur in massive blooms  100,000 km 2  During blooms E. huxleyi cell numbers usually outnumber those of all other species combined  Frequently they account for 80 or 90% of the total number of phytoplankton SeaWiFS satellite image of bloom off Newfoundland in the western Atlantic on 21 July 1999

26. Emiliania huxleyi Makes Alkenones

27. U K’ 37 Varies with Temperature Alkenone unsaturation global calibration Alkenone unsaturation global calibration  U K’ 37 determined in core top sediment samples  SST from from Levitus ocean atlas  Figure from Muller et al. (1998)

28. Global U K’ 37 SST Correlation