Climate change in the past

What is an ice-age? When will the next ice age start?
Has the Greenland ice sheet always been as large as today?
What clues about past climate are hiding in the Greenland ice sheet which could be several hundred thousand years old?

Published 09.04.2007

Did you know that the CO2 level today is twice as high as it was during the last ice age? Did you know that the temperature on Greenland has been 10-15 degrees colder than today?

Did you know that Norway has been covered by an ice cap that was more than 1 km thick?

Thursday April 12 researcher Kerim H. Nisancioglu at the Bjerknes Research Centre will answer questions concerned with climate in the past. The netmeeting is staged by Arnesen Bancroft Explore.

Read the answers below or at ArnesenBancroft here.

ice ages and climate models
Jens Pettersen, 2007-04-12 15:47:40.0

Are modern global climate models able to simulate ice ages? I guess due to computational issues the models used in the IPCC are not simulated for a sufficient long period, but could these models hypothetically simulate a realistic transition from an ice age to the period in between? In case it's difficult, why is this difficult? Poor representation of physical processes, unknown feedbacks, unknown forcings - or a combination of these?

Simulating the ice ages is one of the biggest challenges in climate modeling and it is even harder to simulate the transition (deglaciaion) from the last ice age to the present warm climate (the Holocene). One of the biggest problems is accurately representing the large ice sheets existing at the time in the climate models. These huge ice sheets, such as the Laurentide and the Fennoscandian which covered large parts of North America and Scandinavia, are known to have dissapered in less than 10,000 years. Part of this was due to calving of ice shelves into the North Atlantic and Arctic, and part was due to surface melting. The melting can be accurately represented in climate models, however the and rapid flow of ice and calving (or break off of ice into the ocean) is not well represented in models. The next IPCC will probably include long equilibrium simulations of the last glacial maximum, however simulating the deglaciation is still work in progress.

Kerim

ss
Kamarielle King, 2007-04-11 20:55:57.0

Are Ann & Liv still a live.

Yes, they are both fine.

globle warming
sierra, 2007-04-11 18:32:20.0

when did globle warming start

Global warming due to humans started at the end of the industrial revolution about 50 years ago when we started to burn large amounts of fossil fuels, such as coal, oil and gas. These emit greenhouse gases and conribute to rising temperatures. The rate of global warming has increased significantly during the past 20 years together with rising levels of greenhouse gases accumulated in the atmosphere.

Kerim

the ice is melting
Sara, 2007-04-11 18:31:36.0

what year is the ice just going to melt all the way and there will be no more ice.

This is very hard to say, but there are many scientists working hard to try to predict this. At the moment the annual mean sea ice cover in the Arctic is shrinking by about 3% per decade, with the largest decrease in summer sea ice extent. You could use this to estimate when all the sea ice will be melted, however the rate of melting is very likely going to change in the future. A better way to do this is to use climate models which predict that summer sea ice in the Arctic will be gone within 100 years.

Kerim

climate
Cody, 2007-04-11 18:27:34.0

What is the lowest climate that was ever in the arctic

The Arctic was probably at its coldest about 21,000 years ago during the last ice age. At this time it is likely that the temperatures on Greenland and in the vicinity were about 10 degrees colder than today.

Kerim

globle warming
Avery, 2007-04-11 18:12:29.0

what will happen when all the ice melts

When all the sea ice melts, the temperatures in the Arctic will be quite a bit warmer than today. This is because the dark ocean reflects sunlight much better than the white sea ice which we have in the Arctic today. To melt all ice on land in the Arctic (such as the ice sheet on Greenland) will require a lot longer time. However, if all the ice on Greenland melts, sea level will increase by about 7 meters.

Kerim

Smelting av isen på Grønland
Torodd Hanssen, 2007-04-11 18:10:57.0

Hvis smeltingen av isen på Grønland tar av sted, er det noen beregnig for hvor lang tid det vil ta da ? Og vil ikke vintersesongen bremse en sånn prosess ? Smelter isen på begge polene, eller , som jeg mener å ha lest, blir det kaldere på sydpolen ? Vennlig hilsen Torodd Hanssen

Det er veldig vanskelig å beregne hvor lang tid det vil ta å smelte all isen på Grønland, og vi kan ikke gi ett godt estimat per i dag. Det vi vet er at det vil ta mer enn 100 år, og kanskje noen 1000 år å smelt all isen på Grønland. Om vinteren er det lite eller ingen smelting på Grønland, i dag skjer nesten all smeltingen om sommeren, og så lenge vi har kalde vintere vil det meste av smeltingen skje i sommer sesongen. En mulighet for å bremse smeltingen av Grønlands isen er mer nedbør i form av snø inne på isen, spesielt om vinteren, men det er lite sannsynlig at dette vil kompensere for den økte smeltingen om sommeren som vi har observert så langt, og som vi forventer vil fortsette å øke i framtiden. Når det gjelder den global oppvarmingen så har den den samme effekten på begge polene. Derfor forventer vi også at isen på Antarktis kan begynne å smelte og bevege på seg ettersom den globale temperaturen øker.

Kerim

global warming
luke, 2007-04-10 19:11:25.0

why don't the people who make cars make a car that powered by carbon dioxide?

I don't know, but you can choose to drive cars which are powered by other fuels than gasoline, such as electricity or gas.

Kerim

Ski
Annbancroft and Livarnesen., 2007-04-10 18:25:43.0

WHAT IS THE SEVEN COUNTRIES THAT HAVE LAND IN THE ARCTIC CIRCLE.

Try looking here: http://en.wikipedia.org/wiki/Arctic_circle

Kerim

ART AND GYM AND MUSIC.
LISA, 2007-04-10 18:17:29.0

WHAT IS THE NAME OF THE WATERWAY BETWEEN THE UNITED STATES AND RUSSIA.

This is the Bering Straits.

Kerim

animals
micheal jordan, 2007-04-10 16:19:14.0

what lives in the artice

Quite a few animals live in the Arctic, both at land and in the ocean. E.g. polar bears, raindeer, seals, many types of fish etc.. Some, such as polar bears depend on Arctic sea ice to hunt seals.

Kerim

air
kathryn karna, 2007-04-09 23:53:47.0

Can air be swollowed? How does air get to places? Can air get caught in a bottle?

Sure, air is what your lungs use to breath and the molecules of air are so small they can almost get anywhere. If you want to catch it in a bottle you can, just make sure to seal it properly. The bubbles of ancient air trapped in ice cores are pretty much like sealed bottles of air from times of the past. These "bottles" of air are then extracted by scientists and used to reconstruct climate in the past.

Kerim

endangered species
Emily Bury, 2007-04-09 23:50:18.0

How can I help keep the Manattees safe? What oceans do they live in?

As far as I know these don't live in the Arctic. Have a look at: http://en.wikipedia.org/wiki/Manatees

Kerim

cold
jaylan, 2007-04-09 23:47:41.0

how cold is the Artice ocaen is there any endangered species

Large parts of the Artic ocean is close to the freezing point at the surface, which for sea water is -1.8C. This is why there is a large sea ice cover during most of the year. It is expected that the polar bear will become endangered as the Arctic sea ice melts.

Kerim

global warming
gracie, 2007-04-09 23:47:21.0

how can i help stop global warming?

globel warming
stuart durand, 2007-04-09 23:47:19.0

what caused the globel warming

Global warming is caused by the large amounts of greenhouse gases emitted by humans, such as carbon dioxide, and deposited in the atmosphere. These greenhouse gases trap part of the energy received from the sun, leading to rising temperatures at the Earth's surface.

Kerim

WHY DID YOU BECOME A SCIENTIST
GRACIE, 2007-04-09 23:46:05.0

WHY DID YOU BECOME A SCIENTIST? LIKE DID YOU WANT TO BE A SCIENTIST EVER SINCE YOU WHERE A LITTLE BOY?

Like many little boys I was curious to understand why it rained, or why it snowed. Once I started to learn about this I realized that there was lots more to learn on similar topics; like why is the climate changing, or why had there been an ice age? So, one way to help figure this out was to become a climate scientist.

Kerim

Ice
Jacob Sammons, 2007-04-09 23:44:21.0

How much ice is left.

Today, a large part of the Arctic ocean is covered by sea ice, however it is melting at a rate of approximately 3% per decade.

Kerim

sea animals
Randi, 2007-04-09 23:44:05.0

I was wondering if you knew what the smartest sea animal is.

I would guess it is the dolphin or the killer whale.

CLOUDS
GRACIE K, 2007-04-09 23:43:17.0

how DO CLOUDS FORM LIKE WHAT HAPPENS WHEN IT RAINS???????????????

Clouds are billions of droplets or crystals of water suspended several 1000 meters above the Earth's surface. They are formed as moist air rises and cools and condenses to form clouds - as during a cold winter day you can see your breath when you breath out warm air and it condenses forming a "mini cloud". Once the air in the cloud becomes saturated with water or it gets sufficiently cold it cannot hold as much moisture and it starts to rain (or snow).

Kerim

ice
gracie, 2007-04-09 23:39:45.0

how or why does water freeze into ice?

Freezing is the process whereby a liquid, such as water, turns into a solid, such as ice. This process happens at a freezing point of 0C (32F) for freshwater and -1.8C for sea water, this is due to the high salt content in sea water.

Kerim

Global Warming
Sylvia Szarka, 2007-04-09 21:20:52.0

are Polar bears going to survive?

Polar bears, which depend on a relatively cold climate and the sea ice in the Arctic to hunt their food will have a problem if the global warming continues at the current rate and the Arctic sea ice retreats significantly.

Kerim

water in the artic ocean
nick grandstaff, 2007-04-07 19:02:02.0

How cold is the water in the Artic Ocean?

The water in the Arctic can get as cold as -1.8C, which is the freezing point of sea water.

Kerim

Global Warming
Jazzmon, 2007-04-06 21:42:53.0

Did Global warming happen in the past? Like way back then in the 17 or 18 century?

Yes, there have been times in the past then the Earth experienced global warming. One such period was the Eemian, about 126,000 years ago, before the last ice age. During this period parts of the Greenland ice sheet was melted and the climate in certain regions of the world was warmer than today. However, there are few if any periods in the past when the rate of increase in temperature has been as fast as it is today.

Kerim

blueyed_blonde@hotmail.com
Brittany Nolan, 2007-04-06 18:08:16.0

how do we know what is causing global warming and how do we solve it and save the polar bears ? im curious cause i love polar bears but there coming extinc and its sad thank you for your time by .

There are several factors causing global warming, however at present the biggest contributor is the manmade emissions of greenhouse gases such as carbon dioxide from burning coal, oil and gas. However, it is important to note that the direct warming effect of increasing greenhouse gases is enhanced by feedbacks, such as melting Arctic sea ice. Once you have a warming, the Arctic sea ice retreats (melts) and exposes the dark ocean surface. This dark ocean surface absorbs more energy from the sun (than the bright sea ice cover), causing a further warming. To solve this problem we will have to reduce our consumption of fossil fuels and conserve energy. However, even if we do our best the warming will continue for a few decades due to the large amount of greenhouse gases we have already emitted into the atmosphere.

Kerim

How Can We save the Artic?
Autumn Palmer, 2007-04-05 19:31:43.0

see above

There are several ways to reduce the rate of global warming in the Arctic. For you and me it would be e.g. to drive less cars and take fewer trips on planes. We could also use less energy for heating and lighting our houses and offices.

Kerim

science
tiz, 2007-04-05 19:21:43.0

How cold can it get in the artic?

The Arctic can get very cold in the winter, as cold as -70C in extremes.

Kerim

global warming
meghan golden, 2007-04-05 18:47:52.0

if global warming gets worst than polar bears probably will be endangered so how do scientists they plan to save them?

Scientist are working hard at predicting what will happen to the climate and the sea ice in the Arctic, as well as the animals that live there. However, scientists cannot change the current and predicted warming of the Arctic. Instead we help politicans and people like you and me understand what will happen if we don't do anything to stop global warming.

Kerim

global warminig
koolisaa, 2007-04-05 18:47:30.0

what can we do to stop global warming and how can we help.What is goin to happening to the earth and all the amnimal that need the cold weather and not the warm.I would like to know if there are certain things that people are doin that ia making the problem of global warming worse.thanks and can you answer at sleece@comcast.net.Thanks again bye

Glad to hear that you want to help stop global warming. For you and me there are quite a few things we can do: e.g. reduce our dependency on cars, and instead take public transport or bike/walk to work and school, insulate our homes better to save on heating, turn off our electric applicances (PCs, lights, etc) when not in use, etc. All these things help reduce our emissions of the greenhouse gases which contribute to global warming. Animals, such as polar bears, which depend on a relatively cold climate and the sea ice in the Arctic to hunt their food will have a problem if the global warming continues at the current rate and the Arctic sea ice retreats significantly.

Kerim

science
Mike Oar, 2007-04-05 18:40:13.0

Do you think that the polar bears and penguins are going to make the sevier global warming.I really hope so because polar bears and penguins are my favorite artic animal.Plaese respnd at Oarfamily@comcast.net.

Animals, such as polar bears, which depend on a relatively cold climate and the sea ice in the Arctic to hunt their food will have a problem if the global warming continues at the current rate and the Arctic sea ice retreats significantly. Penguins live around Antarctica and are not as dependent on the sea ice as polar bears. However, we will have to ask the biologists how they will be doing in a warmer climate.

Kerim

science
bacroft, 2007-04-05 00:05:43.0

Why is globel warming happening?

Global warming is caused by the large amounts of greenhouse gases emitted by humans, such as CO2, and deposited in the atmosphere. These greenhouse gases trap part of the energy received from the sun, leading to rising temperatures at the Earth's surface.

Kerim

global warming
kalyn, 2007-04-04 20:19:29.0

how can we help global warming

See earlier answer (koolisaa)

global warming
Reagan, 2007-04-04 20:17:33.0

Are the animals in the ocean going to survive global warming

Animals, such as polar bears, which depend on a relatively cold climate and the sea ice in the Arctic to hunt their food will have a problem if the global warming continues at the current rate and the Arctic sea ice retreats significantly. However, most fish living in the ocean will probably survive global warming.

Kerim

science
nicole harvey, 2007-04-04 20:07:23.0

who are you and are you a real scienceteiest

Yes, I am one of many scientists working on understanding what causes climate change as well as what might have caused climate change in the past, such as during the last ice age 21,000 years ago.

Kerim

science
Nicole Harvey, 2007-04-04 19:55:30.0

how did globalwarming star?

polar bears
sean, 2007-04-04 16:35:35.0

why do polar bears attitude change in global warming

Polar bears are addapted to hunt on the sea ice and will either have to change their habits once the sea ice retreats, or face problems in finding food.

Kerim

global worming
madeline, 2007-04-03 18:55:06.0

why is global warming important?

Global warming is important because it causes the temperatures to rise and the seasons to change, and ultimately the sea level to rise so much that it will affect people living at the coast.

Kerim

past climate
chris white, 2007-04-03 18:52:43.0

how do you find out what the climate was at a certain time in the past?

There are several ways to find out about climate change in the past. Some of our best records come from long ice cores extracted from the ice caps on Greenland and on Antarctica. These can be as several kilometers long and are archives of past climate. From analysing the ice in these cores we can find information about temperature as far back as 1 million years ago. We can also measure the amount of atmospheric greenhouse gases in the past, such as carbon dioxide and methane. This ancient air is stored in tiny bubbles in the ice cores and can be carefully extracted and measured.

Kerim

fossiels
laura, 2007-04-03 18:52:42.0

were do you find fossiels?

Another important way of understanding past climate change is to extract long sediment cores from the bottom of the ocean. These long cores of mud contain tiny fossils of animals living in the past. From these fossils we can learn about past climate, such as the temperature of the oceans during the last ice age, 21,000 years ago.

Kerim

Ice and Water
Emma, 2007-04-03 18:46:26.0

Is there more water or ice?

There is a lot more water than ice. About 70% of the Earth's surface is covered by oceans which have a mean depth of 4 km, whereas ice covers about 3% of the Earth's surface and is about 3 km thick (such as Antarctica and Greenland) .

Kerim

global warming
Isaac Radank, 2007-04-03 17:44:50.0

What is global warming

See next answer (Noah Lee)

reading
Noah Lee, 2007-04-03 16:38:10.0

Howis global warming happening?

extinct animals
Mrs. Miller's 2nd grade class, 2007-04-03 15:54:09.0

Do you think that any arctic animals will become extinct because of global warming

global warming
bobby, 2007-04-02 23:35:10.0

what is global warming?

See answer above (Noah Lee).

Kerim

Sience
Kristiana Carnivale, 2007-04-02 20:56:25.0

Are there panguines there?

Hi, no there are no penguins in the Arctic, they live in the southern hemisphere in Antarctica.

Kerim

earth
leah, 2007-04-02 20:47:35.0

will the fish and land anmals dye when the water gose up.

No, if you are thinking of what will happen as sea level rises, then this will not have much to say for the fish and the land animals. It is rather the people living along the coast close to sealevel which will have problems with rising sea level.

Kerim

Global Warming
Celia Torrey, 2007-03-30 21:22:37.0

Is there any way to stop Global Warming? I am upset with how little progress is being made.

There are several ways to reduce the rate of global warming. For you and me it would be e.g. to drive less cars and take fewer trips on planes. We could also use less energy for heating and lighting our houses and offices. However, there is no way of stopping global warming immediately as we have already emitted a large amount of greenhouse gases into the atmosphere. These will remain there for some time to come and result in a warmer climate.

Kerim

Ice shelfs
Cyera C., 2007-03-30 19:07:29.0

If the ice shelfs are falling off, wouldn't it be because of globel warming?

Yes, it is quite likely that the break up of the ice shelves such as the Larsen B ice shelft in Antarctica is due to global warming and that there will be more events like this in the future, as the ice shelves are very vulnerable to rising ocean temperatures as well as changes in sea level.

Kerim

Ice Shelfs
Rachel A., 2007-03-30 19:05:49.0

What are ice shelfs and how are they made?

An ice shelf is a thick floating slab of ice that forms at the coast where an ice sheet reaches the ocean. The largest ice shelves are found in Antarctica, such as the Ross and the Filchner-Ronne ice shelves. However, there are also ice shelfs in the Arctic off the coast of Greenland.

Kerim

globle
Natasha, 2007-03-30 18:29:44.0

why do we have globle wornings.

global warming
Jackie dewerff, 2007-03-30 18:15:42.0

Why do polar need coldness to live?

Polar bears depend on a relatively cold climate and the sea ice in the Arctic to hunt their food. Once the climate gets warmer the sea ice will retreat/melt and it will be harder for the polar bears to hunt food.

Kerim

globalwarming
brianna, 2007-03-30 15:12:39.0

how could we stop global warming?

For you and me there are quite a few things we can do: e.g. reduce our dependency on cars, and instead take public transport or bike/walk to work and school, insulate our homes better to save on heating, turn off our electric applicances (PCs, lights, etc) when not in use, etc. All these things help reduce our emissions of the greenhouse gases which contribute to global warming.

Kerim