Crash Course In Climate ChangeEveryone is talking about climate change at the moment – but there's so much information coming from so many places, it can be hard to make sense of it all.
So what is climate change, and what's causing it?
When the Sun's energy reaches the top of our atmosphere, about half of it is reflected back into space, and the other half penetrates to the surface. The energy that does reach the surface warms the land and oceans, and in turn, the land and oceans radiate heat back into the atmosphere. Greenhouse gases – such as carbon dioxide, water vapour, and various others – absorb some of this radiated heat, acting like a blanket, and keeping the earth warm enough to sustain life. This is called the natural greenhouse effect, and this is the way it's always worked.Trees absorb carbon dioxide and release oxygen. When a tree falls over in the forest and starts to decompose, it releases that carbon dioxide. Another tree will grow nearby and absorb it again, before eventually going the same way as the first tree. The process repeats continuously, and is called the natural carbon cycle, and if left alone, the level of carbon dioxide in the atmosphere would always be the same.
The natural carbon cycle is being disturbed at the moment due to human activity. By digging up and burning coal and oil, we're pumping the atmosphere with more carbon dioxide than all of the trees can handle. As a result, the level of carbon dioxide in the atmosphere is increasing. In fact, we have more carbon dioxide in the atmosphere now
than we have had at any other time in the last 420,000 years. The earth's blanket of greenhouse gases is becoming thicker, trapping more and more heat, and further warming the planet. This is called the enhanced greenhouse effect, often referred to as global warming or climate change.
But I heard that there were 31,000 scientists who signed a petition denying the link between greenhouse gases and climate change...
It's often claimed that 31,000 or more scientists have signed “a petition” denying the link between greenhouse gas emissions and climate change. But it is well known that the great majority of people on these kinds of lists are not practising research scientists with PhDs, and of those who are, very few are qualified climate scientists, or climatologists. The vast majority of qualified climatologists agree that humans are significantly contributing to climate change.
Don't some scientists believe we're heading into another ice age?
There's a popular misconception that in the 1970's "all of the scientists" predicted that we were heading into another ice age. This is one of those persistent assertions that is repeated endlessly, but which has very little basis in fact. It is a complete myth that there was any kind of consensus among climate scientists in the 1970s that we were heading into a cool period – in fact there was far more concern about warming. The myth's basis lies in the fact that some observers and members of the media at the time – and even today – focused their attention on the one or two scientific papers which suggested an ice age, and ignored the 40 to 50
others which said the complete opposite – that we were headed for global warming.
But the earth has been cooling since 1998, hasn't it?
No. I want to introduce you to a concept known as "cherry-picking" - this means basically coming up with a claim, then using little snippets of the data to support it, ignoring the rest of the data which clearly shows that the claim is false – as opposed to looking at the data first and THEN working out what it means.
In this case, the cherry-picking has involved choosing particular years, like 1998, to try to show 'trends' that don't exist. 1998 is the key here - it was hot. Real hot. The years 1997- 1998 saw a major temperature spike from the strong El Niño in the Pacific, so if we take a big hot El Niño year like 1998 as a starting point, then of course the years immediately following it during the neutral and La Niña phases (the opposite of El Niño) are going to be relatively cooler. Compared to 1998, 2008 was a little cooler. So if you put just those two years on a graph, then you could make it look like the place is cooling down. But if you look at the years 1999 or 2000, 2008 was much hotter than those – and much hotter than any other year for a very long time before 1998.
Because 1998 was so hot, it's a year which is very commonly used by climate skeptics to demonstrate again that we're "heading for another ice age" – or at the very least that the planet is cooling down again now, so we don't need to worry about any of this climate change stuff anymore.
Why is it such a big deal anyway?
Over the last 100 years, the average global temperature has risen by about 0.7°C. Since 1910, the average temperature in Australia has risen by about 1°C. Although these increases sound very small, they have a big impact – the current best estimates for the future are that by 2030 Australia will face another 1°C increase in average temperature, 20% longer periods of drought, 25% more days of very high or extreme fire danger, and significant increases in storms and other severe weather events. Other generally accepted climate models predict that the temperature in Australia will rise by 0.4-2°C by 2030, and up to 6°C by 2070.
But it's not just we humans who are going to be at risk – for example, an increase of 2°C will shrink the kangaroo's habitat by 48%, and an increase of 6°C will shrink it by 96%. Once you lose one species, several other species which rely on it will be threatened, and much more likely to follow suit.
What can I do about it?
We're not all doomed to grow old in a hot, dry, bushfire-plagued, kangaroo- free future – as long as we do something about it now. We can pressure our governments to take serious action on climate change. We can pass on environmentally-friendly values and behaviours to our children. We can all try to lead more sustainable lives, by making little changes to the things we do every day – and I'll be showing you a whole range of these in future issues of Tribe.
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