Are we leading to the

4th Glacial Period ??

Shaiza Saeed MalikRoll No. 10

M.phil Zoology

Global Freezing-A Review

Arctic Ocean, least covered with ice in 2012.

Arctic Ocean, contradict to predictions, was more covered with ice in 2013.

EVIDENCES GIVEN BY NASA

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

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?

The Greenhouse Effect – due to greenhouse gases which mainly arei. Carbon Dioxide (CO2 )ii. Chlorofluorocarbons ( CFCs )iii. Methane (CH4 )iv. Nitrous Oxide (N2O)

Solar RadiationAerosolsAlbedos

Orbital forcing – Solar radiation redirects here

The chemistry-cloudiness interaction

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

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

In a Nutshell

Thermo-” Temperature“-haline” Salinity

Temperature & salinity affect density.

Density differences affect circulation.

Douglas T. McClureDouglas T. McClureIntro. to Physical OceanographyIntro. to Physical Oceanography11/30/0511/30/05

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.

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….

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)

Top left: AlpsTop right: SvalbardBottom: Iceland

Left: Asian Glaciers ( Pamir & Karakoram)

Right: Canadian Glaciers (204)

Hydrological controlThermal regimeThe type of bed i.e. either Soft beds or Hard beds

CAUSES OF SURGING

Eastern Saint Elias MountainsBlack Rapids GlacierBakaninbreen in SvalbardSkeiararjokull in IcelandWest Fork Glacier in the Alaska Range

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….

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. If any such scenario is noticed the Northern Hemisphere will face intolerable cooling likewise the southern hemisphere will face unbearable warm climate as the Southern Oscillation trend is tending towards El-Niña.

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

PresentationEnds

Professor Dr. Aleem Ahmad KhanInstitute of Pure & Applied BIology

to

My class fellows,

And my friends;

Miss Qurat ul Ann Alvi

&

Miss Asma Batool