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GLOBAL WARMING Johan C. Varekamp Earth & Environmental Sciences Wesleyan University Middletown CT Structure of this presentation 1. Global Warming-real or not? 2. Climate science, models and predictions Source: OSTP Variations of the Earth’s Surface Temperature* *relative to 1961-1990 average Source: IPCC TAR 2001 The Exploration of the West: Conditioned by climate change? WARM Vikings (Eric the Red) -33.50 MGW LIA MWP da Verrazano Columbus Hudson, Block d18O -33.75 -34.00 Boston Massacre -34.25 COLD -34.50 900 1000 1100 1200 1300 1400 1500 Age Years AD 1600 1700 1800 1900 2000 Collapse of the Larsen Ice Shelf near Antarctica - a piece of ice the size of Rhode Island came adrift Melting of the Arctic and Antarctic Ice Caps So these are the data: There is global warming, ice is melting, glaciers are retreating, rainfall patterns are changing, plants and animal species are “moving”, sea level is rising. The real BIG question is: Natural Variability or the “Human Hand”? THE GREENHOUSE EFFECT THE SUN EMITS SHORT WAVELENGTH RADIATION (‘VISIBLE LIGHT’) WHICH PENETRATES THROUGH THE ATMOSPHERE AND HEATS THE SOLID EARTH. THE SOLID EARTH EMITS LONG WAVE LENGTH RADIATION (‘INFRA RED’) WHICH IS ABSORBED ‘ON ITS WAY OUT’ BY THE GREENHOUSE GASES. A THERMAL BLANKET IS THE RESULT Principles of terrestrial climate: Incoming solar radiation equals outgoing terrestrial radiation Rsun = Rterr The magnitude of Rterr depends on Ts (Boltzman Law). Part of the outgoing terrestrial radiation is blocked by greenhouse gases, and the earth warms up a bit to restore the radiative equilibrium GREENHOUSE GASES: H2O, CO2, CH4, N2O, O3, CFC CHANGES IN THE CONCENTRATIONS OF THE GREENHOUSE GASES OVER TIME? Burning of fossil fuels Source: OSTP Deforestation Source: OSTP ANTHROPOGENIC CARBON FLUXES IN THE 1990s: FOSSIL FUEL BURNING: 6 BILLION TONS CARBON/YEAR DEFORESTATION: 1.1 BILLION TONS CARBON/YEAR TOTAL: 7.1 BILLION TONS CARBON/YEAR WHERE IS ALL THAT CO2 GOING?? Source: OSTP • Clear correlation between atmospheric CO2 and temperature over last 160,000 years • Current level of CO2 is outside bounds of natural variability •Rate of change of CO2 is also unprecedented Source: OSTP 2100 If nothing is done to slow greenhouse gas emissions. . . • CO2 concentrations will likely be more than 700 ppm by 2100 • Global average temperatures projected to increase between 2.5 - 10.4°F (1.4 - 5.8 oC) Source: OSTP MUCH OF THE CO2 EMITTED INTO THE ATMOSPHERE DOES NOT STAY THERE TAKEN UP BY PLANTS AND DISSOLVES IN THE OCEANS THE CARBON CYCLE! Predicted CO2 increase from carbon emission records Missing Carbon How do we model future atmospheric CO2 concentrations? • • 1. 2. 3. 4. Apply a carbon cycle model to a range of future Fossil Fuel Flux scenarios Use ‘economic scenarios’ that depend strongly on Population growth rates Economic growth Switch to alternative energy technologies Sharing of technology with the developing world Carbon cycle model from E&ES 132/359 at Wesleyan University Symbols: Mx = mass of carbon Kx = rate constant FFF = Fossil Fuel Flux of Carbon Feedbacks: Bf = Bioforcing factor; depends on CO2(atm) K4 = f(temperature) 1200 1100 CO2 (atm) ppm 1000 THE E&ES 132/359 CARBON CYCLE MODEL YOHE1 YOHE7 SRESA1 SRESA2 SRESB1 PRESENT FUTURE 900 800 700 600 500 400 300 200 1850 1900 1950 2000 Age 2050 2100 To go from atmospheric CO2 concentration change to climate change, we need to know the climate sensitivity parameter, l. The common approach is: DTs = l DF or DF/DTs = 1/l where DF is the ‘radiative forcing’ caused by the increased CO2 concentration. The value of DF can be calculated from the increase in CO2 concentration using an integrated version of deBeers law. DTs is the change in the surface temperature of the earth We can solve for l by taking the first derivative of the ‘greenhouse modified’ Boltzman’s Law F = t sTs4 or dF/dTs = 4F/Ts leading to a l value of 0.3 K/Wm-2. That value equals 0.27 K/Wm-2 for an earth with similar albedo but no atmosphere (no greenhouse). This approach is the most fundamental response function and uses zero climate feedbacks! Climate models use 0.3 - 0.9 K/Wm-2, incorporating various positive and negative feedbacks. 3.0 delta T oC 2.5 THE E&ES 132/359 CLIMATE MODEL (CO2 only!) YOHE 1 YOHE7 SRESA1 SRESA2 SRESB1 PRESENT FUTURE 2.0 1.5 1.0 0.5 0.0 1850 1900 1950 2000 AGE 2050 2100 Temperature Projections (TAR) • Global average temperature is projected to increase by 1.5 to 5.8 °C in 21th century • Projected warming larger than in SAR • Projected rate of warming is high compared to the climate record Source: IPCC TAR 2001 If we continue as we have done for the last 100 years (business-as-usual scenario), we will be looking at a much warmer earth, with many unpredictable side effects (sea level, extreme events, changes in carbon cycle -methane in tundras, methane in clathrates, etc) The Kyoto Protocol • Main aim is to stabilize the concentrations of CO2 and the other GHG in the atmosphere through reductions in carbon emissions • Direct Goal: reduce carbon emissions by ~ 5 % below 1990 emission levels in 1012 • Uses trading of ‘carbon pollution units’ as an incentive for the economically least painful way • Net effect would be that atmospheric CO2 concentrations in 2012 would be about 1-2 ppm below non-treaty levels! 141 countries have ratified the treaty (55% of the carbon emissions), with the big absences in the western world being the USA (20 % of the carbon emissions) and Australia. Large carbon contributors from the emerging economies (but growing fast!) are China, India and Brazil, which are exempt from the protocol. The Kyoto protocol is not the wisdom of scientists nor the folly of the greens, but shows the courage of progressive politicians to work on the future of our planet one small step at a time WHICH OF THESE SYMBOLS WILL BE THE STRONGER ONE?? Could these be related? Greenhouse surprises and unexpected events Evidence for very rapid climate change in the past: Younger Dryas cold period The white colours are urban areas: high population density along western LIS Estuary of National Importance • The Urban Sea – more than 28 million people live within a one-hour drive from its shores •LIS contains over 18 trillion gallons of water •LIS watershed > 16,000 square miles • LIS is 170 km long, 30 km wide, mean depth 20 m •A source of food, recreation, and commerce Environmental Issues in LIS Coastal Salt Marsh Degradation Seasonally Hypoxic Bottom Waters Metal Pollution Ecosystem Shifts Regional Issues Eutrophication, Contamination, Invasive Species Global Issues Climate Change SEA LEVEL RISE IN LONG ISLAND SOUND OVER THE LAST MILLENNIUM Wheelers Marsh, Housatonic River, Milford, CT TODAY! FUTURE?? Credit: Ron Rozsa Two Connecticut Marshes Ages of core samples: years AD, core A1C1 • 137Cs, 210Pb • Pollen records (European settlement, chestnut blight) • Metal pollution (dated in marsh cores by 210Pb) 2000 137Cs 1950 1900 Chestnut blight 210Pb 1850 1800 Onset of hatting industry 1750 1700 Ragweed pollen 1650 1600 0 14C 100 200 300 Hg ppb 400 500 Derive age model: Mean High Water Rise curves (local) V+T, unpub data RSLR curves, CT coast TAR Sea-Level Rise Projections • Global average sea • • level is projected to rise by 10 to 88 cm between 1990 and 2100 Projected rise is slightly lower than the range presented in the SAR (15 to 93 cm) Sea level will continue to rise for hundreds of years after stabilization of greenhouse gas concentrations Source: IPCC TAR 2001 Long Island Sound has suffered from hypoxia for decades: •Result of Global Warming? •Eutrophication? •It has always been like this…... EAST LIS CENTRAL LIS WEST LIS NARROWS Core locations for LIS studies R/V UCONN Sampling mud d15N (o/oo), C. perfringens (nr/gr), Hg (ppb) Hg, ppb d15N 500 C. perf 10000 9. 0 d15N Core A1C1 400 8.5 1000 300 8.0 8. 0 200 7.5 7. 5 100 100 7.0 7. 0 0 800 6. 5 1000 1200 1400 1600 year, AD 1800 10 2000 C. perfringens, nr/gr Hg, ppb 8. 5 MEASURES OF ORGANIC PRODUCTIVITY: •BURIAL RATE OF ORGANIC CARBON •BURIAL RATE OF DIATOM “SKELETONS” (BIOGENIC SILICA) •PRODUCTION RATE OF HETEROTROPHS LIKE FORAMINIFERA Elphidium excavatum Paleo-temperature calculations from Mg/Ca in foram tests: (Mg/Ca)f = A10BT •The parameters A and B are empirically fitted with core-top samples to obtain a mean annual modern LIS bottom water temperature of ~12.5 C •The mixing model suggests that (Ca/Mg)w is not salinity-sensitive in the range of modern LIS salinities Core A1C1 MWP LIA MGW DRY WET The d13C* value indicates the amount of oxidized Corg that was added to the bottom water column. The d13C* value serves as an indirect proxy for OCI or Oxygen Consumption Index (Level of Paleo Oxygenation) -73.80 -73.30 -72.80 New York -72.30 New London 0.00 -0.50 d13C* per mille -1.00 -1.50 -2.00 -2.50 1996/1997 -3.00 1961 Buzas -3.50 LongitudeLinear MWP % organic Carbon and d13C* Corg % d13C* 0 2.6 -1 -2 CORE A1C1 1.8 -3 1.4 1.0 800 -4 1000 1200 1400 1600 Year AD 1800 -5 2000 d13C* Corg % 2.2 Observations: •Since 1850 increase in pollutants (Hg), sewage, different N sources, and increased foram productivity •Carbon storage in LIS sediments has increased by ~4-5X in the last 150 years. Higher Corg burial rates in Western LIS compared to Central and East LIS •E-W gradient in BSi: about 2.5 % in Central LIS, up to 4.5 % in WLIS. Biogenic Silica storage also increased over the last 150 years •Sediment accumulation rates increased several-fold as well==> land use changes Carbon isotopes became “lighter” since early 1800’s which is mainly the effect of increased organic carbon burdens (and oxidation), minor salinity effects Hypoxia may have occurred for 200 years but no evidence for hypoxia in central LIS prior to 1800!! Anthropogenic Effect! Temperature record conform known climate trends CONCLUSIONS (1): • Global warming is here! Its effects have been documented extensively worldwide • The human hand is, according to many, very visible • Projections for the future are riddled with uncertainties, but all show further warming CONCLUSIONS (2) IMPACTS ON LIS: • Paleo-temperature record in LIS since ~900 AD shows MWP, LIA and evidence for MGW • Highest salinity in LIS occurred during the MWP, lowest during the LIA • Possibly more salinity variability in the 20th century CONCLUSIONS (3) Major environmental changes in the early 1800’s: increased Corg and Bsi storage, isotopically lighter carbon, lower O2 levels in bottom waters, sewage indicators, changed N sources and metal pollutants CONCLUSIONS (4) • Hypoxic events may have occurred since the early 1800’s but were absent before that time. They are severe in the late 20th century. Why? – Enhanced productivity==> more Corg – Modern global warming==> higher rate of Corg decompositon and increased water stratification HYPOXIA NEED A COMBINATION OF HIGH BWT AND HIGH Corg LOADING Work done with funding from the CT SeaGrant College Program, EPA and the CTDEP-administered Lobster Research Fund and efforts by many Wesleyan University students. The early history of LIS (according to JCV) Long Island is a moraine pushed up by the glaciers and LIS is a depression sitting in front of that pile of material When the glaciers started melting (20,000 years BP), LIS filled with fresh water forming Glacial Lake Connecticut Glacial Lake Connecticut drained around 16,000 years BP and LIS was dry for 1000’s of years The sea came into LIS around 10,000 years BP Native Americans settled around 12,000 years BP in CT