Ice core records provide an important proxy for climate change.

Slides:



Advertisements
Similar presentations
1 Sea-Level changes. What causes the sea level to change over time? Questions:
Advertisements

GEOS 112 Lecture Topics 4/28/03 Read Chapter 12 (Glaciers) Final Exam – Monday, May 5 1:00pm 1.Types of Glaciers; 2.Glacier Formation, Mass Balance, and.
Climate Variability on Millennial Time Scales Introduction Dansgaard-Oeschger events Heinrich events Younger Dryas event Deglacial meltwater Meridional.
Deglaciation Timing of Millennial-Scale Climate Change in Antarctica and Greenland During the Last Glacial Period Thomas Blunier and Edward Brook, 2001.
1 Last Glacial Maximum (~20K yrs ago) and afterwards What was climate like during LGM? What happened to end LGM? How has climate varied since LGM? What.
11/3 papers review.
Abrupt Climate Change Evidence of climate changes that are too abrupt to be explained orbitally.
OXYGEN ISOTOPES B.C. Schreiber U. Washington Dept. Earth & Space Science To be used only for scholarly purposes, consistent with “fair use” as prescribed.
Sea Ice Presented by: Dorothy Gurgacz.
Millennial-Scale Oscillations Many are rapid enough to affect human life spans Many are rapid enough to affect human life spans Largest and best defined.
Carbon System Controls on CO 2 Increase biologic carbon pump in coastal and tropical ocean Increase carbon pump in Antarctic Change chemistry of Antarctic.
Stratigraphy of climate change Lecture 19. The predominant power in this spectrum is at about 100,000, 41,000 and ,000 years.
Abrupt changes in atmospheric circulation from Greenland Ice Cores.
Climate through Earth history
Composite of Sea Level – for last 600 k years. Note that SL was not always extremely low during glacial periods. From Rabineau et al, EPSL, 2006.
Brief Climate Discussion William F. Ryan Department of Meteorology The Pennsylvania State University.
The Last Glacial Maximum (LGM) Lesson 1 Starter Slides on the nature and timing of the LGM.
POLAR EXPLORER i EXPLORING SEA LEVEL RISE As a polar explorer you and your team will be collecting evidence of changes occurring throughout the world that.
Rising Temperatures. Various Temperature Reconstructions from
Can Global Warming trigger rapid climate change?.
5. Future climate predictions Global average temperature and sea-level are projected to rise under all IPCC scenarios Temperature: +1.8°C (B1) to +4.0°C.
Ice Ages and Climate Change Chestnut Ridge, NY Jan 23 in the year 16,004 BC.
{ Natural Changes in Climate.  8.9 Long Term and Short Term Changes in Climate  8.10 Feedback Loops and Climate  8.11 Clues to Past Climates.
Climates of Geologic Time Current Weather Finish Ice Core Research Overview and Historical Perspective The Pleistocene and Holocene For Next Class: Read.
Goals for this section 1.EXPLAIN the feedback mechanism believed to have maintained Earth's average temperature within the range of liquid water over 100s.
Paleoclimatology Why is it important? Angela Colbert Climate Modeling Group October 24, 2011.
Greenhouse Effect* Two transparent windows:  Solar radiation – visible (  m)  Earth radiation – infrared (7-15  m) Major infrared absorbers:
Climate Change Global Warming Greenhouse Effect
Subsurface Currents The Oceans in Motion. Subsurface Currents 1.Mechanics 2.Deep water formation 3.The Importance of the Global Conveyer Belt.
Multi-year time scale variations El Nino and La Nina are important phenomena Occur every ~2 to 7 years when typical ocean-atmosphere circulation breaks.
OC 450: Orbital Controls on Climate (Chaps 8 and 10) Main Points: Small cyclic variations in the earth’s orbital characteristics affect the distribution.
MORE ON CLIMATE. WEATHER IS NATURE’S MECHANISM TO BLANCE TEMPORARY DIFFERENCES IN PRESSURE WITHIN OVERALL ATMOSPHERIC CIRCULATION. WHEN THE DIFFERENCES.
Characterizing and understanding the Quaternary Glacial/Interglacial cycles Earth’s Climate and Environment: Past, Present, and Future GEOL 3100.
FIELD TRIP: USGS CORE LAB / ICE CORE LAB Friday September 9, 2011 Western Interior Paleontological Society Paul E. Belanger, Ph.D. WIPS Past-President.
A bipolar perspective on past climate change (and expectations for information from the Third Pole) Valérie Masson-Delmotte Laboratoire des Sciences du.
Are We Getting Warmer?. How do you take a planets temperature?  If you have them, then thermometers spread around the earth can tell us the average temperature.
Lecture 27: Climate Change in the Last Years Ch. 13.
Are We Getting Warmer?. Is the Earth getting warmer? 1.Yes 2.No.
Chapter 11 Orbital-Scale Changes in Carbon Dioxide and Methane Reporter : Yu-Ching Chen Date : May 22, 2003 (Thursday)
CLIMATE CHANGE THE GREAT DEBATE Session 5.
Arctic and Antarctic Review Glacier Arctic Global WarmAntarctic Misc Q $100 Q $200 Q $300 Q $400 Q $500 Q $100 Q $200 Q $300 Q $400 Q $500 Final Jeopardy.
Lecture 29: Millennial Changes in Other Regions
CO 2 and Climate Change. Lisiecki & Raymo,
Timing of high latitude peatland initiation since the Last Glacial Maximum Pirita Oksanen, University of Bristol, School of Geographical Sciences Contact.
SC.912.E.7.2: Analyze the causes of the various kinds of surface and deep water motion within the oceans and their impacts on the transfer of energy between.
Orbital Forcing on Climate Finish Climates of Geologic Time Introduction to Orbital Factors Axial Tilt Axial Precession Changes in Earth’s eccentric orbit.
Hydrosphere – Physical basis of climate spring 2011
FIGURE 19-1 Greenhouse and natural changes Chap. 19: Climate Change in the next 100 to 1000 yrs Natural Variations in Climate.
Interpreting the sedimentary record
Ocean Response to Global Warming/Global Change William Curry Woods Hole Oceanographic Institution Environmental Defense May 12, 2005 Possible changes in.
For the last 60 My, the climate has been ‘cooling down’, and becoming more and more variable over short time scales. (note log time scale).
The Younger Dryas and Rapid Climate Change Bruno Tremblay McGill University
What have we covered so far – the Basic Questions 1. Climate has not always been similar to the present; in fact has rarely been like the present Holocene.
The Surface of the Ice-Age Earth
Art or Science?. Explain the thermal transfers of energy within oceans and the importance of oceanic conveyor belts.
WHAT IS IT AND WHAT ARE SCIENTISTS DOING TO GATHER INFORMATION ABOUT IT? Climate Change.
Years before present This graph shows climate change over the more recent 20,000 years. It shows temperature increase and atmospheric carbon dioxide. Is.
How Convection Currents Affect Weather and Climate.
Aim: study the first order local forcing mechanisms Focusing on 50°-90°S (regional features will average out)
Chapter 4: Weather and Climate Notes
What Causes Heinrich Events?
Our water planet and our water hemisphere
Abrupt climate change
Ice core records provide an important proxy for climate change.
Paleoclimates.
CO2 and Climate Change.
Ocean-Air Interaction
“What Can Dust Reveal about Past Climates
Climate Change - I.
The Oceans in Motion Subsurface Currents.
Presentation transcript:

Ice core records provide an important proxy for climate change.

Long ice core records have been drilled on both the Greenland and Antarctic ice sheets. Ice core records extend back between 800 and 800,000 years.

Simplified model of global atmospheric circulation.

 - fractionation factor

How do we date Ice Cores? Dating of the upper portion of the ice core record can determined using layer counting. Layer counting within cores will typically be applicable to age ranges up to 10 – 20 ky.

Ice formed near the divide will be plastically deformed (thinned) with depth and layer counting cannot be used. Ages can be determined by ice flow modeling. The ice sheet is considered to be frozen to a horizontal base, for modeling purposes.

Dating of ice cores can also use “wiggle-matching” techniques. Timing of July insolation minima at 65° N can be used to assign ages to the timing of ice volume build up as indicated by the marine isotope record.

Gas bubbles trapped in the glacial ice can be used to determine the atmospheric gas concentration at the time of closure. The local temperature reconstructions from the  18 O data can then be directly compared to the atmospheric gas concentrations. The relationship between atmospheric CO 2 concentration and temperature is irrefutable.

The Greenland data show very rapid and very large fluctuations in the the temperature compared to the Antarctic data, although the large-scale warming and cooling trends are similar. This suggests that the driver of rapid climate change is primarily located in the northern hemisphere, where the polar region contains much more open water than in Antarctica. Rapidly disintegrating ice sheets over open ocean could result in changes in atmospheric or oceanic circulation patterns and provide strong positive feedback for temperature change when the ocean goes from a white reflector to dark absorber of solar radiation – or vice versa.

Loess Marine sediment and loess records. Oxygen isotope measurements of benthic foraminifera provide a proxy of global ice volume change. Loess deposition in north- central China is greatest during cold and dry glacial periods. Soils form during warm interglaciations when the summer monsoon is enhanced. Paleomagnetic record of past 2 million years is shown on the right.

Northern hemisphere ice sheets during the LGM (~20 ka).

Neogloboquadrina pachyderma (polar water foraminifera)

The North Atlantic Ocean distribution of the planktonic foraminifera Neogloboquadrina pachyderma at the Last Glacial Maximum (LGM). Compared to the modern distribution (dashed line near Greenland ) this "foram" found a much wider geographic range at the LGM. This data set shows that the polar front moved very far to the south and traveled more zonally across the LGM Atlantic.

Ocean circulation will redistribute heat on the earth’s surface. Deep water formation in the North Atlantic will be strongly controlled by temperature and salinity content of the water.

Position of the polar front based on presence of G. pachyderma in marine sediment cores. What happened between 11,000 – 10, C yr (13,000 – 12,000 cal. yr) ago?

Neogloboquadrina pachyderma (polar water foraminifera)

HO, H3 & H6: smaller number of lithic fragments and different provenance (European source?).

BINGE PHASE- The gradual accumulation of ice on the Laurentide ice sheet led to a gradual increase in its mass, over 6000 years. PURGE PHASE- Once the sheet reached a critical mass, the soft, unconsolidated sub-glacial sediment formed a "slippery lubricant" over which the ice sheet slid, lasting around 750 years. Geothermal heat caused the sub-glacial sediment to thaw once the ice volume was large enough to prevent the escape of heat into the atmosphere. The mathematics of the system are consistent with a 7,000-year periodicity, similar to that observed if H3 and H6 are indeed Heinrich events. BINGE-PURGE MODEL (MacAyeal, 1993) Kitchen-based oscillator model. Container on axle slowly fills with water until container becomes unstable (water level rises above axle) and reaches tipping point. Spills contents and then flips upright again to refill with water.

EXTERNAL FORCING: AMOC (Atlantic Meridonial Overturning Circulation) Slowdown: 1. A change in the mode of oceanic circulation favors a reduction in North Atlantic Deep Water formation and an AMOC slowdown. With reduced convection, the subsurface oceanic layer progressively warms, increasing the rate of basal melting under the Labrador Sea ice shelf. 2. Once the depth of crevasses in the ice shelf represents a high proportion of the thinning ice shelf, this latter abruptly collapses. A pronounced peak in calving is produced. 3. The missing buttressing effect previously exerted by the ice shelf favors a strong ice-stream acceleration, thus transporting inland-ice and detritus into the Atlantic that translate (i) into a sea-level rise of up to 2 m and (ii) into the Heinrich layer observed in marine sediments.

(A) Location of core sites with records discussed in text (red dots). Marcott S A et al. PNAS 2011;108: ©2011 by National Academy of Sciences

(A) δ18O record from Antarctic EPICA (European Project for Ice Coring in Antarctica) Dronning Maud Land ice core (37) on revised age model (38). Marcott S A et al. PNAS 2011;108: ©2011 by National Academy of Sciences Lower Mg/Ca ratios in benthic forams relate to colder temperatures. Empirical studies have shown that more Mg +2 can be incorporated into the calcite lattice structure of CaCO 3 with warmer water temperatures. Antarctic EPICA (European Project for Ice Coring in Antarctica NGRIP (North Greenland Ice Core Project)

Schematics of the Heinrich event 1. Alvarez-Solas J, Ramstein G PNAS 2011;108:E1359-E1360 ©2011 by National Academy of Sciences

Heinrich Events appear to coincide and may represent severe D-O (Dansgaard-Oeschger) events. Ultimate mechanism triggering the slowdown in the AMOC may be small gradual changes in solar output (i.e., similar to Little Ice Age event).

European pollen records are consistent with the Greenland ice core (Grip) record. During the YD interval arctic herbs dominate the pollen record as glacial conditions returned to Europe. The YD interval ended abruptly and warm conditions returned to Europe.

Did the drainage of glacial Lake Agassiz into the North Atlantic trigger the YD?

Shutting down NADW production will impact surface ocean currents, such as the Gulf Stream. Think about the impact on northern Europe.