Ice AgesIce Ages

Effects on Climate, Weather, Effects on Climate, Weather, & Geography& Geography

Ice AgeIce Age

Referring to a long period of time in Referring to a long period of time in the reduction of earth’s the reduction of earth’s surfacesurface & & atmospheric atmospheric temperaturetemperature

Expansion of continental Expansion of continental iceice sheetssheets & & polar ice polar ice

Large & Small EventsLarge & Small Events

We’ve had at least We’ve had at least 44 large ice age large ice age periods & periods & dozensdozens of smaller events. of smaller events.

The The lastlast ice age was approx ice age was approx 2.5 MYA2.5 MYA Advancing & retreating ice sheets Advancing & retreating ice sheets

(glacial) generally occurs in (glacial) generally occurs in cyclescycles every 40,000 to every 40,000 to 100,000100,000 years years

Advancing & Retreating IceAdvancing & Retreating Ice

Glacial is Glacial is advancingadvancing ice ice Interglacial is Interglacial is retreatingretreating ice ice The The lastlast glacial period glacial period endedended 10,000 10,000

years agoyears ago

Glacial PeriodGlacial Period

Generally Generally coolercooler drier climate over drier climate over much of the earthmuch of the earth

Sea levels are Sea levels are lowerlower due to water due to water retained as iceretained as ice

Interglacial PeriodInterglacial Period

Earth has been in an interglacial Earth has been in an interglacial period for > period for > 10,00010,000 years years

Climate Climate warmswarms

Glaciers form in places where the air Glaciers form in places where the air temperature never gets warm enough to temperature never gets warm enough to

completely melt the snow.  Over the years, the completely melt the snow.  Over the years, the snow becomes deeper as new snow falls.snow becomes deeper as new snow falls.

Causes of Ice AgesCauses of Ice Ages

Several factors including: alignment of the Several factors including: alignment of the planets / planets / tilttilt of the earth / sun’s of the earth / sun’s gravitational pull on earth / gravitational pull on earth / wobblewobble (spin of (spin of the earth – because it is not completely the earth – because it is not completely round) round)

Climate patterns influence glaciations, Climate patterns influence glaciations, including including oceanocean currentscurrents..

All of this effects weather – which is All of this effects weather – which is different from climatedifferent from climate

On a 42,000 year cycle, the earth wobbles and the angle of the On a 42,000 year cycle, the earth wobbles and the angle of the axis, with respect to the plane of revolution around the sun, varies axis, with respect to the plane of revolution around the sun, varies

between 22.1 – 24.5 degrees between 22.1 – 24.5 degrees

Earth’s WobbleEarth’s Wobble

Less of an angle than our current Less of an angle than our current 23.45° means less seasonal 23.45° means less seasonal differences between the Northern and differences between the Northern and Southern Hemispheres while a Southern Hemispheres while a greater angle means greater seasonal greater angle means greater seasonal differences (i.e. a warmer summer differences (i.e. a warmer summer and cooler winter). and cooler winter).

Climate & WeatherClimate & Weather

ClimateClimate is a given tolerance of is a given tolerance of temperature & moisture in specific region temperature & moisture in specific region of earth measured over a given period of of earth measured over a given period of time.time.

Weather is the Weather is the day to day day to day effects of effects of temperature / moisture in a given area.temperature / moisture in a given area.

Weather changes Weather changes dailydaily. Climate is a broad . Climate is a broad range of temp & moisture over a long range of temp & moisture over a long period of time, with period of time, with changeschanges occurring occurring slowlyslowly..

Ice Age Meltdown – 20,000 YAIce Age Meltdown – 20,000 YA

Much of the Northern Hemisphere Much of the Northern Hemisphere was was coveredcovered by ice by ice sheetssheets..

Threatened the Threatened the survivalsurvival of all living of all living things, including H. sapiens.things, including H. sapiens.

Ocean Currents & Climate ChangeOcean Currents & Climate Change

Ocean currents are a Ocean currents are a primaryprimary source source of climate (heat / cold / moisture) of climate (heat / cold / moisture) around the planetaround the planet

There is an “ocean conveyor belt” of There is an “ocean conveyor belt” of cold & warm water cold & warm water flowflow (current) (current) within the within the oceansoceans around the world. around the world.

{warm water rises / cold water sinks {warm water rises / cold water sinks AND fresh water rises / salt water AND fresh water rises / salt water sinks}sinks}

During the Meltdown of the last Ice AgeDuring the Meltdown of the last Ice Age Fresh Fresh coldcold water runoff poured into the ocean water runoff poured into the ocean Instead of sinking, the fresh water (ice) is Instead of sinking, the fresh water (ice) is

lighterlighter & stayed on ocean surface – & stayed on ocean surface – preventingpreventing the ocean conveyor systemthe ocean conveyor system

Atmospheric Temp dropped Atmospheric Temp dropped 1212 degrees in 20 degrees in 20 yearsyears & created a mini-ice age {Younger Dryas & created a mini-ice age {Younger Dryas event} event}

Repeat EventRepeat Event

This event occurred approx This event occurred approx 66 times times between 18,000 – 8000 years ago, between 18,000 – 8000 years ago, with repeated climate with repeated climate shiftsshifts around around the world.the world.

All living things needed to quickly All living things needed to quickly adaptadapt to a constant changing climate to a constant changing climate

Climate Change – Geography ChangeClimate Change – Geography Change Glacial ice from the last ice age was up to 2 Glacial ice from the last ice age was up to 2 milesmiles

thickthick 2525 % of the planet was covered in % of the planet was covered in iceice Lower sea levels showed land Lower sea levels showed land bridgesbridges between between

Siberia & Alaska / land between France & England / Siberia & Alaska / land between France & England / Florida was much Florida was much widerwider

When the ice melted – runoff created enormous When the ice melted – runoff created enormous lakeslakes / valleys / erosion of hill sides and numerous / valleys / erosion of hill sides and numerous geographic changes - 60,000 geographic changes - 60,000 trilliontrillion tons of water tons of water covered more of the earth than before the ice agecovered more of the earth than before the ice age

Sea level rose several Sea level rose several hundredhundred feet feet

TodayToday

Temperature has risen Temperature has risen 1010 degrees overall degrees overall since the last ice agesince the last ice age

Sea level has risen 1 foot every Sea level has risen 1 foot every centurycentury We are in a global warming We are in a global warming trendtrend – not the – not the

*“man-made” global warming {*pollution}*“man-made” global warming {*pollution} With the With the additionaddition of pollution {green of pollution {green

house gases-COhouse gases-CO22}, melting ice caps can }, melting ice caps can change change oceanocean currents & climate patterns currents & climate patterns – creating – creating anotheranother ice age sooner than the ice age sooner than the naturalnatural cycle of change cycle of change

The FutureThe Future

Before and after projection of parts Before and after projection of parts of Spain due to global warming.of Spain due to global warming.