3Isotopes Atomic nucleus occupies only tiny part of the whole atom. Nucleus consists on nucleons: protons – with a positive electric charge, and neutrons – electrically neutral.The electric charges of proton and electron are equall. The mass of nucleons is about 2000 times bigger than mass of electron, the mass of proton is slightly bigger than the mass of proton (neutron = proton + electron)Atoms with the same number of protons, but differ with the number of neutrons are called isotopesAtomic number of element represents the number of protons in its nucleus.Mass number of element represents the number of nucleons (protons and neutrons) in its nucleus.Mass numberElement symbolAtomic number
4Isotope measurementsSome elements can have several stable isotopes – different types of atoms with different numbers of neutrons. (Number of protons in the nucleus define the element, number of neutrons define the isotope). The more neutrons in the nuclues the haviers the atmos.There are three stable isotopes of hydrogen, they are called: hydrogen(H), deuterium (D) i tritium (T).Here are also two stable isotopes of oxygen:
5H218O, H216O and HD16O in 0,2% of H218O and in 0,03% of HD16O. The particle of water consists of two atoms of hydrogen and one atom of oxygen. In relation of their isotopes three different water particles can be found:H218O, H216O and HD16OStandard Mean Ocean Water (SMOW) consists in 99,76% of H216O,in 0,2% of H218O and in 0,03% of HD16O.
7The snow falling of Greenland glaciers has 18O in the range 23 -38‰.The snow falling of Antarctic glaciers has 18O in the range -18 -60‰.In the case of HDO:
8Ratio 18O/16OIsotope 16O is lighter and evaporates faster than 18O. In normal conditions it returns to ocean together with precipitation. In glacial times 16O is trapped in the ice and a relative increase of 18O is observed in oceans. In warm periods, ice melts and the percentage of 16O increases.
9How can we use oxygen isotopes to tell air temperature in the distant past? In high latitude climates the 18O concentration in precipitation varies linearly with mean annual temperature.Assuming this relationship holds for the distant past, the 18O record in ice cores can therefore be used as a proxy for mean annual temperature at the time of precipitation of the snow on the glacier.
10During evaporation, the vapor, and hence clouds and precipitation, are poorer in 18O water than the rest of the water left behind. Precipitation preferentially removes more 18O, so later precipitation is still poorer in 18O. The tops of icecaps, which are cold and at high elevation, receive the most 18O-poor water as precipitation. 18O in ice therefore records air temperature.In contrast, the oceans accumulate excess 18O as 18O-poor water is transferred to the ice sheets. The more ice, the richer the water becomes in 18O. Foraminifera and other organisms growing from the water also become richer in 18O, so their skeletons in ocean sediment record the 18O concentration in sea water and so, indirectly, record ice volume.Ice and ocean sediment records are therefore complementary, each supplying different information about ice and ice formation.
12Volcanic eruptions leave dust and acids on the surface of glaciers Volcanic eruptions leave dust and acids on the surface of glaciers. High winds over dry land blow dust onto glaciers. High winds over open ocean water produces lots of sea salt spray that can also become incorporated into glacial ice. The snow and ice itself contain oxygen and hydrogen isotopes, and bubbles of trapped air. All these can be analyzed to get an idea of what is going on around the mass of glacial ice.
15What we know about greenhouse gases Climatic records in ice cores History of Earth climate can be reconstructed on the basis of analysis of ice cores on Greenland and Anctarctic.Temperatures from measurements of oxygen isotopes.Greenhouse gases in air bubbles trapped in ice cores.
19Ice cores and climate Elisabeth Isaksson Dmitry Divine Lomonosovfonnadrilled in April 1997121 m deep, about 800 yrsProject participants: Norway, The Netherlands, Sweden, Finland, EstoniaSvalbarddrill sitesAustfonnadrilled in 1998 and 1999289 m deep, about 800 yrsProject participants: Japan, NorwayIce cores and climate Elisabeth Isaksson Dmitry DivineHoltedahlfonna(Snøfjellafonna)drilled in April 2005125 m deep, about 400 yrsProject participants: Norway, The Netherlands, Sweden, Finland, Estonia
21Methods of Dating Ice Cores StratigraphyAnnual layersRatio of 18O / 16OElectrical conductivity methodsUsing volcanic eruptions as MarkersMarker: volcanic ash and chemicals washed out of the atmosphere by precipitationuse recorded volcanic eruptions to calibrate age of the ice-coremust know date of the eruption
22Ice cores and climate Elisabeth Isaksson Dmitry Divine Using specific events for dating ice cores Examples from Svalbard ice coresVolcanic eruptions Nuclear weapon testsIce cores and climate Elisabeth Isaksson Dmitry DivineLaki 1783Kekonen and others, 2002Pinglot and others, 2003
23Depth –age relationship Ice cores and climate Elisabeth Isaksson Dmitry DivineIce cores have layer thinning due to pure shear which means that if sample size is consistant the number per time unit will decrease with depth
30CO2 concentration and temperature 3703203130CO2 (ppm) AntarcticaSST (°C) Tropical Pacific2702928Is there a correlation between carbon dioxide levels and temperatures? If we compare carbon dioxide measurements from Antarctica with sea surface temperatures from the tropical Pacific, we find that there is a high coincidence of carbon dioxide levels and temperatures in the past. 220272617025600000400000200000czas (lata BP)
31Sea level during last 450 000 years 203130-2029-40Sea Level (m)28SST (°C) Tropical Pacific-6027-80This graph shows sea levels of the Red Sea over the last 450,000 years. If we overlay sea surface temperatures, we can see a direct correlation between sea levels and temperature. In fact, most of the rise in sea levels is due to the expansion of water at higher temperatures, rather than the melting of ice. 26-100-1202545040035030025020015010050time (thousand years BP)
39Water isotopes in deep-sea cores The “Ice Volume” effect-Light isotope removed from ocean, locked into large ice sheets. Ocean d18O shift (+1.5‰) recorded in marine carbonates that grew during glacial.growing glaciersdeep-seaforaminiferashadow.eas.gatech.edu/~kcobb/isochem/lectures/lecture8.pptSPECMAP – standard benthic d18O record,used to date marine sediments of unknown age
40Coral records of paleo-precipitation Theory: 1) more rain = lighter d18O“amount” effect2) surface seawater d18Owill become lighter3) coral d18O lightershadow.eas.gatech.edu/~kcobb/isochem/lectures/lecture8.pptCole and Fairbanks, 1990
41Water isotopes in speleothems (cave stalagmites) Theory: 1) δ18O of speleothem = δ18O of precipitation2) δ8O of precipitation function of temperature (mid- tohigh-latitudes) and/or amount of rainfall (low latitudes)shadow.eas.gatech.edu/~kcobb/isochem/lectures/lecture8.pptWang et al., Science , 2001
42After: Reconstructing & simulating past climate variability. , J. F After: Reconstructing & simulating past climate variability., J.F. Gonzales Rouco
43After: Reconstructing & simulating past climate variability. , J. F After: Reconstructing & simulating past climate variability., J.F. Gonzales Rouco
44Borehole temperature profiles in central Greenland
45Historical data notes about harvest, corn prices blooming dates (cheeries from Japan more than 1000 years)sailing conditions (ice bergs aroud Iceland)dates of lakes freezing(Japan)notes about weather in old church cronicles (calendars)cave paintingscharacteristic features of housesweather descriptions
54Jones, Osborn and Briffa (2001) Science Potential sources of information about temperature before 1800Jones, Osborn and Briffa (2001) Science
55Potential sources of information about humidity before 1800
56Archive measurements element Instrumental Direct T, P, SLP Historical Records/diaries etc.T, P, stormsTree ringsWidthsDensityIsotopesT, PTIce coresAccumulationMelt layersChemical compositionPCirculationCoralsGrowthSST, SalinitycavesVarves in lakesBiological composition/pollenVarves in the oceanBiological/chemical cmposition
59Źródła wiedzy o klimacie i środowisku Dane instrumentalneDane historyczneDane pośrednieDane pośrednie rzadko niosą informację o jednym tylko elemencie pogody (klimatu).Odczytanie informacji wymaga datowania i kalibracji
60Mariners’ logs, recording dates and positions of iceberg sightings Cape SpearMariners’ logs, recording dates and positions of iceberg sightings, can also be used. Sea ice effectively cut navigation between Greenland and Iceland after (Unfortunately, Cabot didn’t keep good records, so his notes are of no use). In Iceland, correlation between bad ice years and good years for sheep, and vice versa.Mariners’ logs, recording dates and positions of iceberg sightings
61pierścienie przyrostów drzew proporcje izotopów tlenu 18O/16O w wapiennych muszlach mikroorganizmów oceanicznychskład powietrza uwięzionego w lodzie grenlandzkim i antarktycznymzasięgi gatunków o wyraźnych preferencjach klimatycznych
62Western Brook Pond, Gros Morne Glacial features, eg troughs & striations, indicate climate change in areas no longer covered by glaciers. Both these areas were deglaciated about 12,000 years agoHearts Delight
63Okres połowicznego rozpadu rozpad betaW wyniku rozpadu beta otrzymujemy pierwiastek o wyższej liczbie atomowejrozpad alfaw wyniku rozpadu alfa otrzymujemy pierwiastek o niższej liczbie atomowej
64Fluktuacje długości Grosser Aletsch w Alpach Szwajcarskich w ciągu ostatnich 2000 lat. Brazdil i in. 2005
65Datowanie za pomocą węgla C-14 powstawanie węgla C-14 w przyrodziebombardowanie atmosfery przez promieniowanie kosmiczneWęgiel C-14 ulega rozpadowi betaokres połowicznego rozpadu węgla wynosi 5730 lat
66Źródła wiedzy o klimacie w przeszłości "proxy data" – dane pośrednie o czynnikach zależnych od panujących warunków klimatycznych:pierścienie przyrostów drzewproporcje izotopów tlenu 18O/16O w wapiennych muszlach mikroorganizmów oceanicznychskład powietrza uwięzionego w lodzie grenlandzkim i antarktycznymzasięgi gatunków o wyraźnych preferencjach klimatycznych