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Climate change is arguably the biggest threat to human existence in current times. But what exactly is it and why should you be concerned?

Well, let’s start with the weather. There is the weather and there is the climate and despite opinions, the two are very different and not interchangeable. Climate is what you expect, and weather is what actually happens. When an area’s climate is described, it gives you a sense of what to expect, but not what the weather will actually be like when you get there.

And this is what is changing – the climate. Scotland’s climate is already changing with milder wetter winters, and hotter drier summers, and whilst you may think “Great! No more snow and lovely long Mediterranean summers”, the fact of the matter is that these changes will have major implications on how we live.

If you thought it was getting wetter in Scotland you were right. Since 1970 annual rainfall in Scotland has increased by about 13%, and it’s going to keep on rising. In addition, the temperature has increased by just over 1% since 1950’s and sea levels have risen by about 1.4mm per year. Whilst these numbers might seem trivial, the problem is, they are still rising.

So why is all this happening?

The Earth is surrounded by a blanket called the atmosphere. This blanket is made up of gasses including nitrogen, methane, oxygen, carbon dioxide and water vapour. Nitrogen and oxygen make up 99% of the atmosphere and have little effect on the Earth’s temperature, however the remaining gasses, of which carbon dioxide (CO2) is just 0.041%, trap heat and keep the Earth at a temperature that is (currently) habitable.

The more CO2 we emit, the more of this heat-trapping gas there is in the atmosphere and the worse the problem. And whilst CO2 is a very small percentage of all the heat-trapping gasses, it has a big influence on how much heat escapes into space.

Levels of CO2 in the atmosphere are currently the highest they have been for 3 million years.

Greenhouse gasses are measured in parts-per-million (PPM), and the amount of CO2 in the atmosphere is currently, according to NASA, at about 413ppm.

The last time CO2 levels were this high the planet was 3-4°C warmer, trees were growing near the South Pole, sea levels were 20 meters higher… and humans did not exist.

The safe level for CO2 was 350ppm and we passed this in 1988. Since then levels have skyrocketed.

If we stopped emitting CO2 today, to try and get back down to safe levels of greenhouse gasses in the atmosphere, it would take thousands of years.

“If we keep carbon emissions going at the current rate, by the end of the century we will have 1,000ppm,” said Martin Siegert, a geophysicist and climate-change scientist at Imperial College London.

The previously low levels of CO2 that were in the atmosphere before the industrial revolution started in 1760, were maintained by plants and animals which removed CO2 from the air and then buried it. This carbon (CO2) formed coal seams, gas and oil fields (fossil fuels), and for the past 250 years we’ve been digging it up and putting it back into the atmosphere.