16 | 11 | 2013
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Global Warming the Facts

Global Warming The Facts

Famine Children

Climate is important. Did you know that up to a quarter of Scots died in a colder-wetter period in the 1690s? Even today, there are still around 20,000 extra deaths in the UK each winter. The poor and elderly are the worst hit. This is because the rising cost of energy to heat homes is leading to what is called "fuel poverty". This means people cannot afford to heat their homes enough to keep healthy. This is particularly bad for the elderly who are often at home all day and sometimes are ill or unable to move around and keep warm so they need warmer homes. This means they have to spend a lot more of their money on heating their homes and often their pensions are not enough to allow them to do this.

And climate has changed history. The famines in the 1690s during the cold period bankrupted many Scottish landowners. When a project to create a Scottish colony in America called the Darien scheme also failed, Scotland had so little money that leading Scots felt there was no choice but to join with England. So, climate led directly to the downfall of Scotland as an independent nation.

Plants Love CO2

Plants need CO2 just like they need water. If plants did not have CO2 they would not be able to grow leaves or roots and they would die. Did you know that in the past there was a lot more CO2? It was because plants were so hungry for this CO2 that its level fell from 7500ppm down to levels we see today. Did that affect temperature? Well see for yourself on the graph. CO2 levels (red line) have fallen by some 93% over the last 500million years, but whilst temperatures (green line) have varied have they risen or fallen or stayed more or less the same? The evidence tells us that whilst CO2 levels have fallen temperature have not changed much which tells us that CO2 has little impact on global temperatures. But more importantly, it shows that current CO2 are at an unprecedented low level. Plants do not like. If water in Scotland were as scarce as CO2 , Scotland would be as dry as the Sahara! Is it any surprise that all scientific studies show plants benefit from more CO2?

Recent Global Warming is Not Unusual

Many people are worried about recent warming because some claim it is "unprecedented" meaning that there hasn't been warming so fast before. When did people begin to believe this? In the 1970s people worried about a period of cooling and forecast something called “global cooling” suggesting the world was heading to another ice age. But then it warmed & many of the same people like NASA (who gets money if people to research this type of thing they can convince government there is a problem) began telling everyone that the world was warming at an alarming rate that had never been seen before.

This is not true!

The temperature rose...

the same amount;

for the same time,

and finally stopped warming,

between1910 & 1940

as it did from 1970 to 2000.

Definition: Greenhouse Effect

"Greenhouse warming" is named after the way a greenhouse gets warmer even though it has the same amount of sunshine as the rest of the garden. In a greenhouse, this is because the sun shining on the inside of the greenhouse heats the air, but the glass stops the warm air escaping. But when people talk about the "greenhouse effect" this is different because all the air of the atmosphere is trapped by gravity and none of it can escape whether or not there are so called "greenhouse gases".

What is important is something called "infra red radiation", which is just a fancy name for the kind of "heat" you can feel if you put your hands up toward something hot (without touching). Usually we don't notice this heat because, so long as everything around us is warm, we don't notice we are loosing heat this way because everything else is radiating its heat back. But if you go out on a starry winter night without any clouds you will feel how cold it can be when there is very little to stop your heat being lost to intense cold of space. Luckily, the atmosphere does stop some of this heat because of what are called "greenhouse gases" otherwise it would be so cold you would not want to go outside.

The most important greenhouse gas is evaporated water (called water vapour) which alone makes the world about 30°C warmer than it would be without this water vapour. Without this greenhouse gas, the average daytime temperature of equatorial countries like the Congo (30°C) would be as cold as North Alaska. Britain & the US would be very quickly covered in ice and snow and uninhabitable. However, other gases like CO2 add about 3°C extra warmth. Without this warming, the south of England would be like Scotland and France would be like England. So, this 3°C extra warming from gases like CO2 is important but no as important as water vapour.

Is the Recent Warming Due To CO2 Greenhouse Effect?

Scientists can measure the how much heat would be lost if we did not have CO2 using laboratory experiments. Because CO2 levels have been increasing since at least 1958 when the first accurate global measurements stated, some people think these caused the recent warming of 0.48°C from 1970 to 2000. However Scientists can work out from laboratory experiments how much this rising CO2 would have increased global temperatures and that figure is just 0.16°C. So, most of the 0.48°C cannot be to the greenhouse effect of CO2 and is unexplained. However some people think they know better than this science and think that the whole 0.48°C must be due to humans in some way even though the same level of warming was seen from 1910 to 1940 which must be largely due to natural variation of the earth's climate. What do you think? Do you trust laboratory experiments or do you believe those who say "it must be man-made"?

Climate Changes Naturally

by Hubert Lamb who founded the UK Climate Research Unit

Before people started believing the world was heading to catastrophic warming, it was widely accepted that the world had been warmer in the medieval period when grapes were grown in Northern England and it was colder in the “little ice-age” when frost fairs were held on the Thames river in London and many glaciers grew. Then when a lot of money became available to people to research "global warming" they stopped talking about past changes and started telling everyone that the latest warming was very unusual. Today you will hear academics talking about “melting polar ice”. As the graph above shows, this is not at all unexpected as we have just been through a colder period. Would it be the end of the world if the climate were warm enough for "Greenland" to be Green again as it may well have been in the medieval period when the Norse first explored the area.

Natural Climate Change Can Explains It All

Climate has always varied naturally. So how do we know whether the warming in the 20th Century was man-made? Scientists have a way to tell these things called a "controlled experiment". If for example, a scientists wanted to know how much better plants grow with CO2 they could give some plants more CO2 and see what happens. But how do they know whether they might have grown just as well without so much CO2? The answer is simple: you grow two lots of plants, one with enhanced CO2 and one without. Unfortunately, we don't have two worlds so that we can try this experiment with global temperature and CO2. But, fortunately, the world has almost provided a natural example of this test. As the figure shows, between 1910 and 1940 the climate warmed as much as it did between 1970 and 2000 at a time we know there was far less CO2 being produced from burning fossil fuels. So we know this warming must be due to something other than CO2. So, even though we don't know what caused this early 20th century warming, we do know it wasn't CO2. So why couldn't the unexplained warming from 1970 to 2000 also have the same origin? Climate has naturally varied in the past so why couldn't this natural variation explain the warming from 1970 to 2000?