So I take my education in history and my love of science and try to meld the two and use history as an excuse to be obsessed with science. Here's an example of this:

No, this flood didn't happen in the past few years or even hundreds of years.

13,350 years ago there was a giant lake that was 3 times the size of Lake Ontario today (it was in the same location, too).  An ice dam held the water in this lake, which is called Lake Iroquois, until the Earth began to warm.

The ice dam broke and millions of gallons of water washed down the Hudson River valley to the south.

Here's a map depicting the lake and what happened.

I have attached a photo of the flood path.

The flood washed many animals into the waters, including Woolly Mammoths.  My geology professor told me that Mastodon tusks were found in sediment when waters were dredged in New York City...these were tusks left over from the giant flood that washed these animals down the Hudson River.

Here's a link to a great read about it-

http://www.whoi.edu/oceanus/viewArticle.do?id=5078

If you're ambitious you can do more research on Lake Iroquois and if you're REALLY interested in this stuff read up on Lake Agassiz- this lake was larger than the Caspian Sea and covered a huge part of North America.  When this lake drained (due to the thawing of Hudson Bay) it raised world sea levels 1-3 meters and, arguably, shut down the North Atlantic Thermohaline Circulation causing global cooling called the Younger Dryas stadial.

Hello again! I tried to make this blog entertaining and informative and hope you are able to take away some knowledge from this post.  I welcome all comments and opinions on this subject! Enjoy!

From roughly the year 1200 to the year 1800 the Earth was thrown into a Little Ice Age.  The Little Ice Age was a period of time in human history where many people suffered at the hand of a climate we did not understand or prepare for.  This can happen again. The question is why did it start and when will it happen again?  I hope this blog answers some of these questions.

What happened during the Little Ice Age?

• Crop Failure:

-   Across the world the failure of agricultural output created hunger and famine. 

• Towns disappeared:

-   Farms and villages in the Swiss Alps were crushed by glaciers in the mid 17th century.

• Transportation change:

-   In New York City, New York Harbor froze in 1780 allowing people to walk from Manhattan to Staten Island.

-   Iceland had ice surrounding it for miles in each direction.  Harbors closed.

• Geographic change: 

-   Fairs were held on the frozen ice in southern England on the River Thames. 

• Decrease in population:

-   Iceland, in particular, had its population drop by half.  Some believe this was due in part to increased amounts of       fluoride in humans due to 1783 eruption (which added ash to the atmosphere, more on this later). 

-   World population increase slowed and decreased in many areas, especially in Europe.

• Armies walked across water:

-   In 1658 a Swedish army was able to march across ice to invade Copenhagen in Denmark.

• Colonies vanished:

-   The Norse colonies in Greenland vanished by the 15th century due to crop failure and livestock dying in the increasingly harsh winters.

• Permanent snow on Ethiopian mountains:

-   In Africa mountains that do not have snow on them year round today had snow on them for years.

• Ice in June:

-   Lake Superior still had ice on it in June.

• Native American crisis:

-   Leagues were organized to respond to the food shortage among tribes.

• Glacier advancing:

-   Many glaciers, even in Glacier National Park, experienced advancement in the late 18th and 19th centuries.

• Witch-hunting:

-   The lack of crops, cold temperatures, and odd weather contributed to the mass hysteria that was the witch hunts in Europe.  Prosecutors believed witches were destroying crops and changing weather.



Now that we have the effects what were the potential causes of this Little Ice Age?

1.     The Sun- The Sun develops something called sunspots on its surface.  They are basically “cooler” areas of the Sun.  In response to the cooler area with less convection there is a large amount of magnetic activity.  Sometimes this magnetic activity is released in a massive explosion called a CME.  These are what give Earth radiation and cause the northern lights. 

If sunspot activity is reduced there are less CME’s and therefore a smaller amount of radiation/heat reaching Earth.  There was a large reduction in solar activity during the Little Ice Age.  Every 11 years the Sun reaches its solar maximum in terms of sunspots.  We are at solar maximum.

2.    Volcanoes- Volcanoes erupting on the surface of the Earth create ash plumes that travel high into the atmosphere.  Sometimes this ash is so plentiful that it prevents heat from reaching the surface of the Earth.  In turn the Earth cools.  During the Little Ice Age many volcanoes erupted on large scales and sent ash high into the atmosphere.  In fact, in 1815 the volcano Tambora in Indonesia erupted.  The next year was called the “Year Without a Summer.”  Snow and ice were reported in June and JULY in North America!

3.    Thermohaline circulation- The large circulation process of water in the Earth’s oceans is elaborate and vital to our climate.  Salt water is heavier than fresh water.  Because of this a circulation is created in the ocean that carries warm water from the equator north to the coast of Europe.  This is why England has a climate much like the northeast states in the United States (warm water brings warmer air).  If the circulation shuts down England resembles northern Canada.

The theory is that a large amount of fresh water, created by the warming period immediately preceding the Little Ice Age, increased the amount of fresh water from icecaps in the ocean.  This in turn shut down the circulation and caused the northern hemisphere to cool. 

4. Orbital patterns- Cycles in the Earth’s orbit around the Sun can create cooling and warming periods.  If this is true then the cooling process will continue until we reach another ice age in around 4,000 years.  This is a normal pattern on Earth.



So what? Why should any of this matter today? 

The reason I bring this up is because, contrary to the seemingly apocalyptic reporting of CME's from the Sun by the media, the Sun should be at its 11 year maximum for sunspots (which produce CME's).  Though we have had some sunspots there are hardly as many as previous solar maximums.  This indicates that the Sun may be entering a solar minimum, much like that during the Little Ice Age.  If you followed earlier, fewer sunspots mean less heat reaching the Earth. 

What does this mean for us?  Many scientists believe nothing. The impact of the Sun is far less than the impact of greenhouse gasses in the atmosphere.  The gasses will offset the cooling process and prevent another Little Ice Age. 

Other scientists disagree.  The Sun is the MAIN source of heat for the surface of the planet.  Some heat is produced by Earth's core but the amounts pale in comparison to the energy sent by the Sun.  Taking this into account a reduction in solar output would coincide with a direct decrease in latent heat on Earth.  This would lead to a cooling of the planet and in turn a Little Ice Age that may, once again, have similar impacts as the one last millenia.  Given the 7 billion people on Earth, there would mass food shortages and large geographical changes, among other things.

When will this happen?  I am not sure.  The reduction in sunspots seems to just be appearing now.  It is possible the Sun is simply going through a mid-life crisis.  After all it is 5 billion years old and has another 5 billion years left before it burns out.  Next solar maximum may be more impressive than this one.  However, if it is not, then we may start seeing impacts similar to those during the Little Ice Age on Earth.

If a major volcano explodes, such as the super volcano under Yellowstone, then the Earth will certainly be thrown into another Little to full fledged ice age.


What do I think?

Global warming is increasing at a rate unprecedented and it is being contributed to by humans.  In addition to our own contributions there are changes that we are trying to understand on Earth.  Earth goes through patterns and right now it should be cooling, not heating up.  Still, the Sun, if it continues at solar minimum, may quell the speed of global warming in the coming decades due to the decrease in radiation reaching Earth.  Will we see an ice age on the level of the Little Ice Age?  No.  We need to monitor this closely. 

The bottom line: Do not think that tomorrow we will see glaciers crushing towns across the world.  Any climate change takes decades to centuries to complete; however, we should be concerned with the increase in global temperatures and in turn what impacts this will have on our Earth.  Barring any major volcanic eruptions or other unforeseen events, I do not believe we will see another ice age for thousands of years.  In the end the only thing we can do is live in the moment and hope for the best.  The Earth will do what it wants and we are just along for the ride!

Please feel free to comment.  This took a long time to research and started as a sentence but quickly exploded into an essay.  Thanks for reading!


Sources:

Emmanuel Le Roy Ladurie (1971). Times of Feast, Times of Famine: a History of Climate Since the Year 1000. Barbara Bray. Garden City, NY: Doubleday.

Lamb, HH (1972). "The cold Little Ice Age climate of about 1550 to 1800". Climate: present, past and future. London: Methuen.

Stone, Richard (2004-11-19). "Iceland's Doomsday Scenario?"  http://www.sciencemag.org/content/306/5700/1278

Broecker WS (February 2000). "Was a change in thermohaline circulation responsible for the Little Ice Age?"  http://www.pnas.org/content/97/4/1339

Rose, David (2012). “Forget global warming…”  http://www.dailymail.co.uk/sciencetech/article-2093264/Forget-global-warming--Cycle-25-need-worry-NASA-scientists-right-Thames-freezing-again.html  

Mandia, Scott.  “Influence of Dramatic Climate…” http://www2.sunysuffolk.edu/mandias/lia/little_ice_age.html  

“Little Ice Age”  http://www.eh-resources.org/timeline/timeline_lia.html