Shock findings suggest vital Atlantic currents are slowing dramatically. Will this soon plunge Europe into winter, turn the Amazon into grassland and cause famine in Asia?

IS EUROPE'S central-heating system about to break down, causing climate chaos around the world? Late last year, oceanographers reported a sudden and shocking slowdown in the currents of the North Atlantic, a critical part of the vast system of ocean circulation that influences temperatures and weather around the world. A shutdown could cause famine in south Asia, kill off the Amazon rainforest and plunge Western Europe into a mini ice age.

However, if you live in Europe, don't order that snow cat just yet. The conclusions reported last year have been dismissed by many climate scientists, who say their models show the current will keep going for at least another hundred years or so. So what is really going on? Are changes in ocean circulation about to turn our lives upside down, or is this something only our grandchildren will have to cope with?

Climate change: The great Atlantic shutdown New Scientist 15^th April 2006

Well what is going on is that a number of scientists around the world are just guessing. There is no other way you can describe the opposing views held by scientists on environmental issues. One minute the human race is on the brink of extinction, pushing the proverbial uphill with a rake, the next minute everything is fine, we will last another 24 hours at least.

So what is a girl to do?  I can’t answer that, better ask Helen; on second thoughts, maybe not. Maybe tax the public, again; sounds like a good idea to me. Any old excuse will do as we are pretty gullible.

Since the 1990s the most over riding environmental concern has been Global Warming. I do not think anyone denies global warming exists (yes even including me if it is defined as the climate is warmer today than say 30 or 40 years ago). What is arguable though is the extent of the warmth and what we do about it.

What I will try and do is separate the hyperbole from the real problems. Some scientists argue that we will experience a climate change increase of 6 degrees by the end of this century but personally most scientists would struggle to produce evidence to show this as plausible. What is being presented to the public is based on distorted political value judgements, limited computer models and assumptions about future technological change. These figures are based on the United Nations climate panel, the IPCC, and these figures and models are the basis for most public policy on climate change in the world.

Greenhouse Gases 101

The predicted increase in world temperatures has been badly defined as “The Greenhouse Effect”. I say badly defined because the world does not work like a garden greenhouse, in fact far from it but I may as well use the common understandable terminology. So here is how it works -

• Greenhouse gases (GH gases) reflect or trap some of the heat radiated from the Earth.
• These gases are water vapour (the largest part of the Greenhouse gases)
• Carbon Dioxide known as CO2
• Methane known as CH4
• Laughing gas or N2O (although no one is laughing at the thought of paying billions for this) and
• CFC and ozone.

It’s the extra or manmade amounts of these gases that are the important components in global warming, and CO2 makes up around 60 percent of the man made components.

These gases act like a blanket and stop some of the heat from the earth escaping which is just as well otherwise the average temperature would be 33 degrees Centigrade cooler (so bear in mind not all Greenhouse gases are evil).

Of the extra man made gases, 80 percent comes from burning coal, oil and gas (normally in power plants) and 20 percent comes from cutting down forests and land changes in the tropics.

Now come in close now and I will explain the real kicker here. About 55 percent of the CO2 is absorbed by the oceans, by northern hemisphere forest re-growth and by plants. The rest is added to the atmosphere and from pre industrial times to now this has added an extra 32 percent of CO2 to the atmosphere.

Lack of historical Data

One of the serious problems that climate change scientists have is a lack of any long term data. We have only used thermometers to record temperatures for the last 150 years. So to know what has happened to the Earths climate over a longer period of time, scientists look for other ways of measuring temperature.

What scientists do is look at proxy indicators; how temperature has affected other objects. So if scientists drill out an ice core sample they can then measure the layers back in time, measure the melted ice, measure any traces of trapped gases in air bubbles etc. Of course none of this will tell you what the temperature was on a balmy night in July 1210 in Oxford, England.

You can also tell (or should that be estimate) temperature by looking a the rings on trees, growth rings on coral and looking at lake or ocean sediments.

Now bear in mind here that all I am doing is repeating what scientists do and believe; I am not saying I believe any of this.

Scientists believe the last interglacial period, the Holocene (which we are still in) began about 10,000 years ago (give or take a day or two).

The earlier temperatures were warmer than temperatures today and melting ice caused the sea to rise about 120 metres (400 feet for the oldies).

The most popular model to try and estimate historical temperatures is the one by Michael Mann and this the one used by the United Nations IPCC organisation (Intergovernmental Panel on Climate Change).

Mann shows a declining temperature from 1000 to 1900 (a trend towards a new ice age) and concludes that not only was the last century the warmest for 1000 years but the 1990’s was the warmest decade and 1998 was the warmest year for the Northern Hemisphere. There is no disagreement that the centuries before 1900 were colder. The time from 1400-1900 was known as the Little Ice Age (and to think they had no central heating!).

There is also no disagreement on what is known as the Medieval Warm Period or the early part of the second millennium. The temperature was 2-3 degrees C warmer which meant the Rocky Mountains snow line was 300 meters higher than today. A number of people have questioned why the Mann data does not show warmer temperatures in the period 1000-1400 (of course this would destroy his famous “hockey stick” temperature chart).

So how does Mann know what the temperature was in 1000 or even 1400 given that the first mercury thermometer was invented in 1714 by Daniel Gabriel Fahrenheit (of course young people today will not know what Fahrenheit is, they only know Celsius, which was invented by Anders Celsius and is different from Centigrade –Google it to find out why). I digress; Mann doesn’t know what the temperature was in 1400. Mann uses tree rings as temperature proxies, and almost exclusively uses North American trees. This of course does bring into question how accurate his so called temperature model is given that –

• Almost all proxies models use are land based
• This ignores the more than 70% of the earth’s surface which is not land (which means it must be, let’s see water). And when was the last time you saw a tree growing in water.
• Tree growth is dependent on many factors aside from temperature.
• Trees mainly grow in the summer, and never at night.

So what does this mean? Well if you use a proxy like trees, they do not accurately measure or record full annual temperatures.

So to claim that today’s temperatures are higher than any time in the last 1000 years is less than accurate given that it –

• Excludes ocean temperatures
• Excludes night temperatures
• Excludes winter temperatures
• Is almost exclusively based on North American data.

So as I said earlier, “What’s a girl to do?”

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