Quiz 5- Ocean Climate Change, Climate Change So Far
Relative humidity
% is measure of how close air is to saturation humidity
Ocean acidification-Evil twin of sea level rise
1/3 of all CO2 produced from fossil fuel burning has ended up in the ocean C02 reacts with seawater, increases acidity H2O+CO2 H2CO3 Carbonic acid Carbonic acid-weak acid, loses hydrogen ion to form bicarbonate ions H2CO3 H+ + HCO3 -1 Or, sheds remaining hydrogen ion to form carbonate HCO3- H+ +CO3 -2
Clausius-Clapeyron relation
Amount of water vapor that fits in a given volume increases by 7% for each degree C warming
Coastal Regions
Areas where impacts of climate change on the ocean most conspicuous-will cause changes to coastal landforms, ecosystems, waterways, human pops. Sea level rise has accelerated over 20th century rates Mid-Atlantic, Gulf of Mexico-Sea level rise greater than observed global rise. Will be affected more than Pacific coast
Heat Waves
As planet gets warmer, there will be more heat waves of greater intensity Associated with semi-stationary domes of high pressure-clear skies, light winds, warm air prolong hot conditions at surface High pressure associated with heat waves-higher summer nighttime minimums, daytime maximums. High pressure projected to increase with increased greenhouse gas emissions Models and observations show heat waves more severe in : US-Southeast, south and upper mid-west, southwest
Mechanism linking climate change to drought
Based on fact that warmer atmosphere can hold more moisture-existing patterns of moisture transport intensified Changes in atmospheric circulation-Paths storm tracks follow are moving closer to poles, expand region Climate models-Subtropical latitudes (15-35 deg. Lat.) lie over world ocean areas where surface warming. Dry areas will show increased drying. Wet regions will get wetter Land surfaces-atmosphere must supply land with moisture
cold snaps
Beneficial to some areas-Longer growing season, more precipitation Many plants require cold spell to flower, produce fruit ex: food: Parsnips, persimmon, collards, carrots, Fruit trees, wheat, other cereal grains animals: Some butterflies and moths require eggs to be exposed to cold before they will hatch sugar maples
Effects of decreased calcification
Calcifying organisms span food chain Coccolithophores (actually have been increasing in numbers), Corals, Coralline algae, lobsters, shrimp, crabs, starfish, crayfish, barnacles, snails, clams, oysters Physiological damage that may occur - Acidification of body fluids-indirect negative impact on food resources - May have to reallocate resources away from feeding and reproduction to maintain internal cell pH -May alter acoustic properties-sound travels farther Developing white sea bass-grow larger ear bones (otoliths) under high CO2 conditions -Young clownfish-Acidified water affects sense of smell, can't find suitable habitat
El Nino/Southern Oscillation events
Causes more storms: Occur every 2-7 years Affects weather mainly in Pacific Warm water extends eastward-reaches coast of S. Am., CA Causes more storms from CA-mid-west, Flooding in S. Am., droughts in Indonesia, Australia Since late '70's, abrupt change to stronger and longer el nino cycles
Social Impacts
Coastal development -less mobile, more vulnerable to impacts Rising sea levels-provide elevated base for storm surges, increased risk of flooding Removal and damage of protective areas increases erosion Salt water intrusion into coastal aquifers
Hurricane Sandy-2012
Deaths, evacuations, power outages, flooding, halting of transportation, stock exchange closed Scientists don't believe directly caused by global warming, but some contributing factors
Deep carbon storage in the ocean
Deep convection sites-Where ocean absorbs and stores greenhouse gases Ocean temps will continue to rise another .4 deg C, even if we stopped increasing greenhouse gas emissions Amount of anthropogenic carbon stored in oceans, as of 1994
Droughts
Defined by: Amount of rainfall, amount of water evaporated, amount stored in soil Palmer Drought Severity Index (PDSI)-Combines monthly precip totals and temps 2010-2012 Drought- La niña intensified in Mid-2011, lasted until early 2012, helped to contribute to current ongoing severe to extreme drought
Wetlands
Degree wetlands affected by sea level rise dependent on: - Capacity to rise its surface to match rising sea level - Rate of boundary erosion - Availability of space to migrate Converting to open water-submergence Increasing salinity Altered flow of rivers-changes in sedimentation rates
Deep ocean currents-Driven by water density
Density of water controlled by temperature (thermo) and salinity (haline) Processes that affect water density drive changes in circulation -Rainfall, ice melt, river outflow dilute water, make less dense, more buoyant -Evaporation, cooling increase salt concentration, make more dense, less buoyant
How do we establish cause and effect for observed climate changes?
Detection and Attribution Studies- Statistical techniques where you can "detect" climate change in a data set. Balance of Evidence-Includes all information: Physics, past climate variations, data on weather and climate. Includes detection and attribution data. Balance of evidence data may show logical correlation, but attribution studies may not due to patchiness of data
Floods
Develop very quickly in response to extremely intensive rainfall Damage crops, foster spread of disease, overwhelm water treatment, economic damage, landslides, erosion
What causes current numbers of tropical cyclones?
Different regions have predictable numbers 6 factors generally necessary: Water temp-at least 26.5 degrees C Rapid cooling High humidity Low amounts of wind shear More than 5 deg. Lat. away from equator Pre existing system of disturbed weather
Coral reefs-Stressors associated with climate change
El Nino events, combined with warming-role in coral bleaching. Sea level decreases-expose reefs, increase in water temps. El Nino bleaching event in 1997-98- 16% worlds reefs lost Ozone depletion- Increase in UV radiation Rise in sea level- May damage or kill through drowning, low light Changes in ocean circulation- Corals live where boundary currents bring warm water Precipitation, dilution with fresh water- Increased in tropics
Link of sea surface temps with cyclone occurrence and tendency
Evidence linking fluctuations of sea surface temps and cyclone activity forced by external factors Studies have shown wind speeds, numbers, energy have increased in last decades Other studies-Changes in observational techniques responsible for changes
Sea level rise-Effect on Eastern US
Expected sea level rise by 2100-1-2M If Greenland and Antarctic sheets melt completely-Global sea level rise of 65M 53% of US pop lives on the 19% of land near coast
cyclonic storms
Form because of pressure differentials- Large low-pressure area near earth's surface Winds generated by mixing of cold dry air and warm wet air-Release of large amounts of latent heat as moist air is carried upwards and condenses best measurements of storms come from flying plane into a storm
Hurricanes
Form in Atlantic or E. Pacific oceans
Cyclones
Form in S. Hemisphere or Indian Ocean
Typhoons
Form in W. Pacific
Cyclonic storms- Increase in societal impact
From beginning of 20th century to present, economic damage caused by hurricanes in US increased tremendously Rise in economic , human loss-Not due to changes in hurricane frequency, but movement of people, infrastructure to coastal regions. Strong winds, heavy rainfall, storm surges Likely to increase, even if global warming trends do not continue
Major bleaching events
Great Barrier Reef Caribbean-Anomalously high sea temps '86-'88 bleaching is greatest threat to reefs
Warming climate-Thermal inertia of oceans
Heat capacity of ocean very large-changes in atmosphere take a long time to affect changes in ocean Change of ocean temps at depths indicator of energy imbalance-Excess heat stored in oceans 80% of warming by greenhouse gases is stored in the upper 760M of the ocean Sea levels rise because water increases volume when heated-Since 1993, thermal expansion has accounted for half of sea level rise
Effects of Heat waves
Heat stroke, death Power outages Wildfires Physical damage-roads, water lines, power transformers detonating Agricultural, crop damage
slowing of ocean conveyer would: would not:
Increase rainfall in Arctic, Antarctica Shifting rainbelts, altering rainfall patterns Colder temps in N. Europe Collapse of plankton stocks, upset of ocean ecosystems Increase in major floods, storms, El Nino events would not: Would not: Stop gulf stream, trigger an ice age
Expected changes due to sea level changes
Increased coastal erosion, inundation Inhibition of primary production Changes in surface water quality Impacts on aquaculture, agriculture Displacement of shore based populations
Estuaries
Increases in mid-latitude rainfall- -Greater volume fresh water entering sea -Increased stratification of water-depletion of oxygen concentrations Sea level rise- increasing salinity as tides move more salt water into estuary Affect aquatic life-jellyfish, oysters, sea grass
Thermohaline ocean conveyor
Initiated in polar regions-density increases when sea ice is formed, and sinks. Surface waters pulled in-initiates deep ocean currents Warm up, become less dense as they travel toward equator. Rise to surface, loop back around, go to South and west to S. Atlantic. Eventually return to N. Atlantic
Lake Chad
Large marshy freshwater lake 20 million people depend on lake for resources Shallow, very sensitive to small changes Increased demand for water, shifting climate patterns each equally responsible for decrease in surface level Likely to disappear in course of 21st century
Predicted Future Drying
Long term predictions of climate change linked to drier conditions in some subtropical regions-US Southwest, Mediterranean, S. Australia, S. Africa, S. Argentina Different type of drought than those caused by la nina IPCC- Predicts extreme droughts increasing from 15-30% by end of century Land area affected b extreme drought: Could increase from 1% (present) to 30% of lands surface by 2100
Ocean acidification and reefs
Lowered calcification rate and density Reef building only occurs when Calcium carbonate precipitation exceeds removal Possible increase in dissolution of coral skeletons
Ocean Chemistry
Made up of chemical compounds, elements, gases, minerals, organic and particulate matter. Ratio of elements always the same Salts-Na, K, Mg, Ca, Cl, Sulfate, HCO3-Total number of dissolved salts always close to 35g/kg seawater Continents-source of chemical input Input of chemicals from black smokers-Fe, Manganese, Cu, Zn, Ag, Au, Pt
Eustatic global sea level rise-Changes in volume of sea water
Melting of land ice and extraction of groundwater-accounts for half of rise Thermal expansion-Accounts for other half of rise 1-2 meters rise expected by 2100 -how we know the rate is going up: they can go back and look where the sea based structures of the Roman empire were placed (historical record), if the rate was same as it was now, would have been way over sea level. Tells us sea level rise is increasing
Clathrates
Methane deposits frozen into ice Found in ocean sediments along continental shelves-Pressure high enough and temps low enough to keep stable Make up significant store or total carbon fossil deposits Destabilized as temps increase Evidence of releases in past linked to climate changes and extinction of deep sea organisms-PETM
La nina storms
Normal condition: Unusually cooler ocean temps in eastern tropical Pacific Warm water near surface blown to west Cold water-hampers formation of clouds and storms More northward placement of jet stream Essential part of drought occurrence in SW US
disruption of conveyer
Shut down 11,000 ya-Drainage of Lake Agassiz into North Atlantic at end of Pleistocene ice age with collapse of ice sheet Contributed to est. 1-3 M sea level rise Likely cause of sudden decrease in global temps
Food chain disruption-
Northern Pacific Aleutian region Sea lions and seals changed habitat due to increase in temp Killer whales changed diet-began feeding on sea otters-led to decline Otters ate fewer sea urchins Sea urchin populations expanded-Overgrazed kelp beds
Increased precipitation
Not worldwide increase-Will vary from region to region Cloud cover-Surface observations suggest increase over large continental regions, consistent with increasing precip Climate models suggest extreme precipitation events will increase about 6% for every 1.8 deg. C rise in temp
Castella Aragonese
Ocean has high levels of carbonic acid due to naturally occurring seafloor vents releasing CO2 Many areas of ocean floor could resemble these conditions by 2100 if CO2 emissions keep growing
Disease and toxins
Parasites and disease causing microbes-can grow faster, become more virulent Parasites in cooler climates are more likely to survive the winter and produce multiple generations of offspring each year, so more fish may become infected. Fish poisoning- Increases at higher temps Already stressed fish more susceptible to disease Toxins-Warm water increases toxicity of pollutants
Gulf stream
Powerful western boundary of N. Atlantic gyre Originates in Gulf of Mexico, follows E coast US, Newfoundland Travels 25-75 mi/day
Global warming changes as predicted, relationship with cyclonic storms and sea surface temps
Predict a 3-5% increase in wind speeds/degree C increase in sea surface temps. Probable that intensity (wind speed and rainfall) will increase if climate continues to warm
Global mean rainfall-Average over all individual rain events
Rainfall totals must match amount of water evaporated from surface of earth Local trends-not directly controlled by need to balance budgets of water and energy for entire globe Local storms-limited only by amount of water stored in air
Chesapeake Bay
Rise of sea level by 2 Ft by end of century, loss of: -beaches -undeveloped dry land -marshes replaced by newly opened water
ocean acidification pH changes
Since industrial revolution, pH has dropped about .1 unit, from 8.179-8.069 Shift in pH creates a large shift in balance of bicarbonate, carbonate ions Estimated to drop .3-.5 units by 2100-7.824 Critical in production of shells of sea organisms Ca2+ + CO3 2- CaCO3 Small shift in pH-large shift in balance of bicarbonate and carbonate ions
Physiological effects of warmer temps on fish
Some fish benefit from warmer temp, grow heavier and larger Fish need more food and oxygen to support higher metabolisms, little energy available for growth, reproduction Oxygen squeeze-Less oxygen in warmer waters
Main ocean gyres
Spirals of ocean circulating currents Flanked by strong western boundary current, weak broad eastern boundary current
Global dimming and effects on water cycle
Sunlight necessary for rainfall-heats ocean, water evaporates, falls as rain . Aerosols reduce sunlight Reduction of solar radiation may have led to failure of monsoon associated with Sahel droughts 70's-80's Major dust storms in Sahara in 2006 caused dimming, cooling over Atlantic-dampening of hurricanes
Sea Level-Affected by
Temperature Anomalies in Earth's gravitational field, sea surface topography Lunar and solar tides Storm surges thermal expansion- warm water simply takes up more space
Other factors that influence storm formation
Vertical wind shear-Differences in speed or direction of winds blowing at different heights Many climate models predict vertical wind shear will increase over N. Atlantic with warming-reduces hurricane activity El Nino-Causes depressed hurricane activity in tropical Atlantic ocean
Changing ocean currents
Very likely circulation in Atlantic will slow during 21st century North Atlantic becoming fresher, warmer-Increased rainfall, melting of glaciers and ice Tropical and subtropical waters becoming saltier Return flow has slowed about 30% in last 50 yrs
Ocean Coasts-Type depends on physical processes
Virtually certain erosion will dominate changes in shoreline position of headlands, spits, barrier islands
Specific humidity
Total amount of water vapor in air Higher the temp, the higher the specific humidity can be before reaching saturation point Warmer climate-Specific humidity will increase, but relative humidity will stay about the same
North Atlantic Current
Transformation of warm subtropical waters into colder subpolar and polar waters
Sahel Region of Africa
Transition zone between tropical forest to south and Sahara desert to North extreme desert and monsoon area Semi-nomadic people dependent on monsoon-Move herds from North to South during dry periods. Permanent settlements in fertile areas Drought: Famine killed 100,000 people
Surface ocean currents-Driven by wind
Transport heat, salt, dissolved nutrients across the oceans Circulation patterns determined by prevailing winds, the Coriolis effect, horizontal and vertical friction At equator winds blow west. Above and below midlatitudes, blow eastward Currents form basin-wide gyres
Rising temps leading to changes in distribution of fish
Tropical, warm water species -Moving farther north-extending range-Mahi Mahi, Swordfish, Blue Marlin, Yellowtail, Albacore. Resident fish will have to compete with new species Cold water spp-Move north or deeper-restricted range: Increase in temps has shifted range of Salmon, Cod, Halibut, trout, whitefish, bass
Projected wetland loss
Virtually certain that tidal wetlands already experiencing submergence by sea-level rise and associated high rates of loss will continue to lose area Quality, quantity, spatial distribution of habitat will change- Resulting from erosion, salinity changes, increased flooding Change in wetland dependent species-habitat loss, migration, reduced populations Tidal Marshes, tidal flats, forested wetlands, estuarine beaches all will be affected-Critical habitat for shore birds, shellfish. Disruption of food chains likely
Changes in plankton distribution
Warmer temps have caused phytoplankton to move northward Changes to bottom of food chain eventually change distribution of fish at top of food chain Affected range of larger fish -Mackerel, Cod
water vapor increase
Water vapor has increased by about 5 % over the years in last 100 years
climate change so far
We experience climate on a local, immediate scale Influence if greenhouse gases on weather not immediately detectable May increase probability that some extremes will be more likely, but by definition these are rare events Climate change will have an effect on the statistics of weather
Evaporation
feeds a storm's rainfall Depends on both water temps and humidity of air-Warmer air can hold more moisture
Positive feedback loop of deep convection currents
feeds storms must remain over water to keep loop running
evaporation and latent heat
heat energy is released when liquid water condensates then freezes, heat energy is absorbed when solid water melts then evaporates
Fisheries- link to climate change and health
more directly linked to climate change than terrestrial animals Aquatic organisms-Poikilothermic (cold blooded) Any changes in temps significantly influence metabolism, growth rate, productivity, seasonal reproduction, susceptibility to diseases and toxins Too cold-metabolism slows, become sluggish Too warm-Metabolism speeds up-digest more rapidly, grow more quickly, have more energy to reproduce
Evidence of changing ocean currents
overall pretty inconclusive, but hints of change in overturning circulation of currents -a 30% reported reduction of the overturning, based on some measurement- not very reliable -deep overflow of water from Nordic Seas into open Atlantic near Iceland, weakening of a key part of this overflow, following a recovery- inconclusive
climate change
overall trend of entire earth's surface toward a different average state
Humidity saturation point
where vapor condenses