Your Outlines? Exam 2?

1. Your Outlines?Exam 2? ?? -> what is the latest news??

2. Coastal Zones and Marine Ecosystems Chapter 6, IPCC (2001)

3. Oceans: so what? • 70% of the Earth’s surface • Regulate the Earth’s climate • Modulate the global biogeochemical cycles • Supplies of resources and products worth trillions of dollars each year • Function as areas of recreation and tourism, medium for transportation, repository of genetic and biological information, sinks for wastes (these functions are also shared by the coastal margins of the oceans)

4. Humans and Oceans • ~ 20% of the world’s human population live w/in 30 km of the sea; ~ 40% live w/in the nearest 100 km of the coast • 600 million people will occupy coastal floodplain land below the 1,000-year flood level by 2100 • climate change will affect the physical, biological, and biogeochemical characteristics of the oceans and coasts at different time and space scales  positive feedback on the climate system • Note: the oceans already under stress. From what? Consequence of this stress?

5. ?: what are the potential impacts of climate change on the coastal zone, marine ecosystems, and marine fisheries • First: what do we know

6. State of Knowledge • Global warming will affect the oceans through changes in sea-surface temperature (SST), sea level, ice cover, ocean circulation, and wave climate • Ocean conveyor belt -> global ocean thermohaline circulation system; emphasizes the role of the global ocean as a climate regulator • Projections: • SST-induced shifts in the geographic distribution of marine biota and changes in biodiversity, particularly in high latitudes • Decrease in ice-infested waters • Sea-level changes from thermal expansion

7. State of knowledge: Low certainty • Changes in the efficiency of carbon uptake through circulation and mixing effects on nutrient availability and primary productivity • Changes in ocean uptake and storage capacity for GHG • Potential instability in the climate system caused by freshwater influx to the oceans and weakening of the ocean conveyor belt

8. Marine Ecosystems: • A general warming of a large part of the world oceans during the past 50 years • Overall increase associated with land-based global temperature trends • Global mean sea-level has risen by about 0.1–0.2 mm yr-1 over the past 3,000 years and by 1–2 mm yr-1 since 1900, with a central value of 1.5 mm yr-1 • Suggested: maximum intensity of tropical cyclones may rise by 10-20%; might persist for longer time due to increased SST

9. Ocean conveyor belt…. • Role in controlling the distribution of heat and GHG • Circulation: driven by differences in seawater temperature and salinity • Some evidence: will weaken (Slow down? Stop?) due to climate change • (more on this later)

10. Marine Ecosystems: Sea Ice… • 11% of the ocean (seasonal) • Affects: • salinity • ocean-atmosphere thermal exchange • Determining the intensity of convention in the ocean, and thus the mean time scale of deep-ocean processes affecting carbon dioxide update and storage • Changes • Large reductions in the extent, thickness and duration of sea ice • Already: significant decrease in spring and summer sea-ice by ~ 10-15% since the 1950s in the northern hemisphere; • may be underestimated due to significant thinning of sea ice in the Arctic; may be as much as 25%between 1950s-1970s

11. Marine Ecosystems: Biological Processes • Can sequester CO2 and remove carbon to the ocean interior: biological pump • Rise in temperature  faster biodegradation + faster dispersal of global organic pollutants … • Photosynthesis (the major process by which marine biota sequester carbon dioxide) – controlled by the availability of nutrients and trace elements (eg: iron) • Climate change could affect the inputs of nutrients and iron to the ocean… • Greatest impact in semi-enclosed seas and bays

12. Also… • CC can shift structure of biological communities in the upper ocean…. Change stratification…can impact the biological bump…

13. Marine Ecosystems: Marine Carbon Dioxide Uptake • Oceans: ~ taken up 30% (great uncertainty) of carbon dioxide emissions between 1980 and 1989 • How? • Burial of organic carbon in marine sediment -> removing atmospheric carbon dioxide for prolonged time periods • But… • If CC could reduce ability to carbon uptake • (latest news: you tell me) • Also: weakening the conveyor belt -> reduce ocean’s ability to absorb carbon dioxide • With a doubling of CO2 scenario, ocean uptake of CO2 dropped by 30% over a 350-yr period

14. Marine Ecosystems: Marine Fish • Because climatic factors affect the biotic and abiotic elements -> they influence the numbers and distribution of fish species • What are the abiotic factors? • Water temperature • Salinity • Nutrients • Sea level • Amount of sea ice • And the biotic factors? • Food availability • Presence and species composition of competitors and predators • Water temperature directly impacts • Spawning and survival of larvae and juveniles, and fish growth • Biological production rate -> food avalability

15. Marine Ecosystems: Marine Fish • Variations (with cycles of 10-60 yrs) in the biomass volume of marine organisms depend on sea temperature and climate • Eg: fishing for cod in the Atlantic Ocean – clear correlation between water temp and catch • Thus: important to consider the ecosystem impacts of climate variations + changes for individual species

16. More on marine fish • Herrings, sardines and anchovies: shortlived species that mature at an early age • Large fluctuations in abundance – associated with changes in the climate-ocean environment • Most fishing regime changes can be related directly to sea-temperature changes, but changes in other physical attributes also can have an impact. • Example: a decrease in wind stress o f Tasmania that reduced large zooplankton production a ff e c ted the density of Jack mackerel, which eliminated the possibility of a commercially viable mackerel fishery

17. As ecosystems change, there may be impacts on the distribution and survival of fishes. • Any changes in natural mortality would be associated with increased predation and other factors such as disease. • Improved growth in the early life stages would improve survival, whereas decreased growth could facilitate increased mortality. • cautious acceptance that climate change will have major positive and negative impacts on the abundance and distribution of marine fish. • Fishing impacts may be particularly harmful if natural declines in productivity occur without corresponding reductions in exploitation rates.

18. Marine Mammals and Seabirds • Sensitive indicators of changes in ocean environments • Fluctuations in marine bird and mammal populations in the North Pacific may be entirely related to climate variations and change • Climate variations since 1990 + overfishing  behavioral changes in killer whales  reduced sea otter abundance  changed the ecology of the kelp forests • The changes in prey resulting from persistent changes in climate appear to be one of the important impacts of a changing climate on the marine mammals that feed from the top of the food chain. • CC  effect access to prey among marine mammals • Eg: ice-free seasons in the Arctic  prolong fasting of polar bears… • Reductions in sea ice have been predicted to alter the seasonal distributions, geographic ranges, migration patterns, nutritionalstatus, reproductive success, and ultimately the abundance of Arctic marine mammals

19. Seabirds • May consume vast amounts of fish (600,000 t/yr in the North Atlantic; 20-30% of the annual pelagic fish production) • Hard to distinguish CC from overfishing • How likely is it to survive?  depends on its ability to alter its migration strategy • Long lifespans and genetic variation within populations enable seabirds to survive adverse short-term environmental events, • However, small populations tied to restricted habitat, such as the Galapagos Penguin may be threatened by long-term climate warming

20. Diseases and Toxicity • Changes in precipitation, pH, water temperature, wind, dissolved CO2, and salinity can affect water quality in estuarine and marine waters. • Some marine disease organisms and algal species are strongly influenced by one or more of these factors • increase in reports of diseases affecting closely monitored marine organisms, such as coral and seagrasses, particularly in the Caribbean and temperate oceans • several viruses, protozoa, and bacteria affected by climatic factors can affect people, by direct contact or by seafood consumption. • Example: bacterium found in oysters; cholera epidemics associated with marine plankton

21. Coastal Systems • Existence of many depends on the land-sea connection • Wide range of environmental conditions: • Salinity (fresh to hypersaline) • Energy (sheltered wetlands to energetic wave-washed shorelines) • Spectrum of climate types: tropical to polar • Exposed to land-source and marine hazards, waves, river flooding, shoreline erosion, biohazards (algal blooms and pollutants) … • Know Box 6.3 and Box 6.4

22. Coastal Systems • Beaches, Barriers, Cliff Coasts • More erosion with CC likely; changes in wave or storm patterns… • What about presence/absence of biotic protection such as mangroves? • Deltaic Coasts (low-lying coastal regions) • Exposed to potential flooding • Nile: significant land loss can result from wave erosion; also: large portions of the Amazon • Saltwater intrusion into freshwater aquifers • Coastal Wetlands • By 2080, sea-level rise  loss of 22% of world’s coastal wetlands (mangrove forest and salt marsh); much already lost • Tropical Reef Coasts • More than 25% of all known marine fish + food source; 58% at risk from human activities. Global CC could be an additional cause • Sea-level rise + increased carbon dioxide levels + temperature… • Latest news… • High-Latitude Coasts (ice-rich coasts)

23. Latest News • Based on current model simulations, the Meridional Overturning Circulation (MOC) of the Atlantic Ocean will very likelyslow down during the 21st century; nevertheless temperatures over the Atlantic and Europe are projected to increase.