El Nino, La Nina, and Climate Change

Quick Links: El Nino La Nina The Year Without A Summer Medieval Warm Period Climate History Ice Age

There has been a lot of talk recently about climate change. There's one inconvenient truth that they forgot to mention...

THE WORLD'S CLIMATE HAS BEEN, AND IS ALWAYS CHANGING.

Global warming is the fashion of the times, and, indeed, there have been changes over the past 10 years or so.

El Nino

La Nina

1998 was the warmest year recorded, so why are they talking about continued warming, when, by definition, temperatures have DECREASED since then?

Well, 1998 was the warmest year on record ₁, tied by 2005, yes, and 2006 was the fifth warmest since 1998, but where does, say, 2000 rank? Surprisingly, 2000 was actually 0.3 degrees BELOW 1998, yet we didn't see global warming talks end then.

A special called "Hot Planet"... at one of the coolest times in nearly 5 years? (Hot Planet aired in late 2000)

Consider for a moment that 1998 was over one half a degree above average. Where did that degree go in, say, 1999? And what happened in 1992 to cause it to be just over a tenth of a degree above average?

It may surprise you to see that these are NOT the largest differences from "average" in Earth's climate history.

In 1816, also known as 'The Year Without A Summer', or 'Eighteen Hundred and Froze to Death', a massive volcanic eruption occurred. Mt. Tambora blew massive clouds of dust and ash into the atmosphere, causing a relatively instantaneous (within a year) change in the climate to colder, for several years. During this time, snow fell in June and August in the Northeast states, while frosts occurred off and on throughout the entire summer. Even the South wasn't spared, as Savannah, Georgia saw a high of only 46 degrees on July 4, 1816. This occurred during a time known as The Little Ice Age. A Little Ice Age is a prolonged cool spell in the Earth's climate, but not severe enough to cause massive glacier advance. Follow this link for information on a true Ice Age.

Normal conditions in July include highs in the 90s in much of the Southern United States, and 80s from Atlanta northward. Some 70s persist along the Great Lakes.

Normal conditions in January, the coldest month, include highs in the 70s in south Florida, 60s in north Florida and southern Georgia, westward to Texas, and 50s in northern and central Georgia up to about Charlotte, westward to around Memphis. The 46 degree high temperature in Savannah was clearly abnormal for any time of year.

It has been even warmer than today, if accounts of an environment suitable for farming, grazing, and settling in Greenland during the Middle Ages are to be believed. There's evidence of wine gardens in Newfoundland around that same time. Vinland = literally, wine-land.

This is what "Green"land looks like today:

Not very much green, huh? At best, the extreme southwest part could be (and, in fact, is) settled. (The northern part isn't ice cap because it's too cold and dry to support enough snow to maintain it, and the eastern part is too rocky). Much of Greenland is tundra and ice cap! It must have been warmer in order to grow crops there!

History of the Global Climate

Just in the past thousand years, there have been numerous changes in the world's climate, from warmth in the Middle Ages to cold in the Renaissance and Scientific Revolution years, to warmth early in the 20th century, to cold in the early years of the Space Age, to warmth today. But what was it like before, say, 1000 AD? While there wasn't a measurement during that time that is accurate to plus or minus a hundredth of a degree, there are clues.

Tree rings and ice cores tell a story, as well as any fossils of plants and animals. Trees generally grow more during a warmer climate and less during a cold one. However, the limiting factor here is that drought or insect infestation can also limit growth. For example, a tree in the Midwest might have thinner rings around, say, 1932. Does this mean that it was colder in the 1930s? Not necessarily. This was during the Dust Bowl, a long period of warm, dry conditions in the Midwest.
La Nina could be a culprit, as hotter, drier conditions tend to occur during the spring, summer, and early fall months over much of the eastern half of the United States. Some areas get more moisture and get colder from mid-fall onward, depending on closeness to the Northwest. 1988- a La Nina year, saw a drought over much of the nation, as did 1995, another La Nina year. So, thinner rings during these times don't necessarily mean colder conditions. If, however, ice cores are thicker around the same time that tree rings are thinner, that may be a good indication.

Just our own continent, North America has changed greatly over the past 400,000 years. There were also changes in Europe, Asia, and Africa during this time, too. Here are some examples of change:

The western states were colder than present.

The Pacific Northwest was mostly a dry tundra or polar desert as opposed to pine forest.
Inland areas were dominated by tundra or a very dry shrubland.
The Southwest was cooler and more moist than today, with some having been grassland or even temperate forest.

Florida was colder and drier than at present.

Tampa Bay didn't exist until after the Ice Age. In fact, the beaches were 100 miles further west.
The lower water table resulted in much of the state being a desert or scrubland.
Northern Florida had northern temperate forest, vestiges of which remain. The great stand of pine trees in the southern states is a holdover of conditions in the Ice Age!

Ice Age

An ice age is a severe, prolonged cold period in the Earth's climate, that leads to glaciation (formation and advance of glaciers). The last Ice Age occurred 12,000 years ago- and the average time between ice ages over the past 400,000 years (an interglacial period) was 10,000 to 15,000 years. So, we should be stocking up on Arctic gear, right? Not necessarily. The interglacial that occurred 400,000 years ago- with the Earth at a similar shaped (less eccentric) orbit to today- lasted 28,000 years ₂.

This is the maximum possible extent of various types of vegetation today. Note that this isn't actual coverage, particularly in northern Alaska and around Hudson Bay (most of that is still tundra), and the Midwest (due to agriculture). It does tell where the plants can potentially grow to.

It's a good thing that we're not in an Ice Age, as the Last Glacial Maximum (maximum extent of ice sheets) stretched to New York State, westward to around Cincinnati, and then into the Great Plains and Rocky Mountains. Based on climate today near ice sheets, at their coldest, New York City would be like Nuuk (Greenland) or Barrow, Alaska, Atlanta would be like Moosonee or Churchill, and Tampa would be like Toronto or Buffalo. That is from a 15 degree drop in annual winter global average temperatures. It's a little misleading, because the Southern Hemisphere fared fairly well in the last Ice Age.

This contrasts quite well. The maximum extent of glaciation in the last Ice Age tells that New York was like Barrow, Alaska, with rolling tundra. Atlanta was like Churchill, mid-taiga conditions. Lastly, our own Tampa Bay area was about as cool as Toronto or Buffalo, but a lot drier. In fact, it was probably more like inner areas of Washington and Oregon- much drier than the moist Pacific areas.

In fact, the image above helps confirm the changes. Of course, it can still get colder than this, and that is what is known as "Snowball Earth", where the world ends up in a runaway ice age, much as it did roughly 300 million years ago. And, of course, there's evidence of dinosaurs having been in Antarctica...

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¹: NOAA/ National Weather Service Climatology

²: Environmental Sciences Division, North America during the last 150,000 years.

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