The document discusses the possibility of entering a fourth glacial period while reviewing evidence related to global warming and cooling. It addresses climate models, particularly the influence of greenhouse gases and thermohaline circulation, and presents conclusions on glacial surges in response to climatic changes. Various aspects such as CO2 levels, global temperature trends, and their implications for future climate scenarios are examined.

2. Are we leading to the
4th Glacial Period ??
Shaiza Saeed Malik
Roll No. 10
M.phil Zoology
Global Freezing-
A Review

3. Arctic Ocean, least
covered with ice in
2012.
Arctic Ocean,
contradict to
predictions, was
more covered with
ice in 2013.
EVIDENCES GIVEN BY NASA

4. Climate model projections were summarized in the
2013 Fifth Assessment Report (AR5) by the Intergovernmental
Panel on Climate Change (IPCC). They indicated that during
the 21st century the global surface temperature is likely to rise
a further. The ranges of these estimates arise from the use of
models with differing sensitivity to greenhouse gas
concentrations.
Global cooling was a conjecture during the 1970s of
imminent cooling of the Earth’s surface
and atmosphere culminating in a period of
extensive glaciations. This hypothesis had little support in
the scientific community, but gained temporary popular
attention due to a combination of a slight downward trend of
temperatures from the 1940s to the early 1970s.
INTRODUCTION

5.  What is the difference between “Global Warming” and
“Global Freezing”?
 How do we come to know about the concentrations of
CO2 in a certain time period?
 Are causes of Global warming and cooling the same?
 What would be the Physical mechanism for the decrease
in temperatures as said by some scientists (mainly
climatologists) specially in the Northern hemisphere?

6.  The Greenhouse Effect – due to
greenhouse gases which mainly are
i. Carbon Dioxide (CO2 )
ii. Chlorofluorocarbons ( CFCs )
iii. Methane (CH4 )
iv. Nitrous Oxide (N2O)
Solar Radiation
Aerosols
Albedos

10. Orbital forcing – Solar radiation redirects here

12. The chemistry-cloudiness
interaction

13. What is Thermohaline Circulation?
Why does it happen?
How is it affected by climate?
How does it affect climate?
How has it changed in the past?
How might it change in the future?
Conclusions….
Thermohaline Circulation

14. Pre requisite knowledge we should have:
 Definition of Advection and Convection
 General global mapping; knowledge of poles, equator,
counter current wind flow, DWF sites, Upwelling sites.
Labrador sea, Greenland sea, Mediterranean sea,
Weddell sea and Ross sea
 Circumpolar and Subpolar movement
 Diapycnal water
Profile of the Drake passage*
Ekman Layer and Transport (physics related)*
 Gyre and gyre circulation*
 Climate Models e.g., Global Climate Models GCMs,
Atlantic Meridional Over tuning Models (AMOs), Pacific
Meridional Over tuning Models (PMOs).
 Southern Oscillation Trends (El-Nino, La-Nina trends)
 NOAA observatories round the globe specially at
Mauna Loa, Hawaii

21. In a Nutshell
Thermo-”  Temperature
“-haline”  Salinity
Temperature & salinity affect
density.
Density differences affect
circulation.
Douglas T. McClureDouglas T. McClure
Intro. to Physical OceanographyIntro. to Physical Oceanography
11/30/0511/30/05

25. Global Warming and Surface freshening:
Both these factors will reduce the density of high latitude surface waters
and inhibit the deep water formation. (S. Rahmstorf, 2006)
 Manabe and Stouffer projected in 1993, a four fold increase in CO2.
Increased CO2 leads to increase in Hydrological cycle which in turn
might collapse the Atlantic thermohaline circulation.

27. What is Glacier Surge?
Why does it happen?
How is it affected by climate?
How does it affect climate?
How has it changed in the past?
How might it change in the future?
Conclusions….

28. What are surging glaciers?
Surge behaviour:
“multi-year oscillation between extended
periods of normal motion and brief
periods of comparatively fast motion.”
(C.F.Raymond, 1987)

30. Top left: Alps
Top right: Svalbard
Bottom: Iceland

31. Left: Asian Glaciers ( Pamir &
Karakoram)
Right: Canadian Glaciers (204)

32. Hydrological control
Thermal regime
The type of bed i.e.
either Soft beds or Hard
beds
CAUSES OF SURGING

33. Eastern Saint Elias Mountains
Black Rapids Glacier
Bakaninbreen in Svalbard
Skeiararjokull in Iceland
West Fork Glacier in the Alaska
Range

34. CONCLUSIONS
In light of the factors of THC and Glacier Surging,
we might be able to discuss:
 Are we in active surging phase(active phase) at
present or not?
If we are in surging phase (active phase), in
Northern hemisphere?, in Southern hemisphere or
both?
Is THC large enough as compared to the
greenhouse effect? To cause decrease in global
warming….
Else than Karakoram glaciers, most of the highest
glaciers have not been seen to increase in Ice
caps….

35. In my point of view the projections of four fold increase of CO2 levels (in
1993) has occurred by now as the accuracy of the measurements as
given by NOAA at Mauna Loa, Hawaii seems to be doubtless.
But with the acceptance of complexity of Climatology and Oceanic
studies, owing to only one aspect we cannot say that Atlantic THC will
surely collapse in coming years though it is now clear that

36.  IPCC – Intergovernmental panel on climate change
 AOGCM- Atmospheric, Oceanic Global Climate Models
 NASA- National Aeronautics and Space Administration
 SCEP report- Study of Critical Environmental Problems
 [GISS, UAH and RSS]
 NSB- National Science Board
 1975 National Academy of Sciences report
 1974 Time Magazine article
 1975 Newsweek article
 1979 WMO conference- World Meteorological Organization

37. Presentation
Ends

38. Professor Dr. Aleem Ahmad Khan
Institute of Pure & Applied BIology
to

39. My class fellows,
And my friends;
Miss Qurat ul ann alvi
&
Miss asMa Batool