I feel a need to help others to understand what is happening with the world’s climate. Just a gentle reminder that ‘weather’ is a brief event, but climate is all about long term moving averages. Everyone would be aware now, that weather records are being broken both in Australia and around the world. Just in Tasmania, we can’t go more than a few months without some record being broken…hot days, hot nights, wind speed, rainfalls, drought periods, frost events… Records are, by their nature, meant to keep changing, but it’s the rate of change that has scientists perplexed and worried.
Very simply, the world’s climate is warming as humans release carbon dioxide into the atmosphere. Carbon dioxide is a potent ‘green house’ gas, trapping heat radiated by the sun. We have managed, since the ‘Industrial Revolution’, to push the atmospheric carbon dioxide levels from 280 ppm (parts per million, tiny eh?) to 400 ppm.
Sceptics (those with vested interests) point to the natural cycles of climate change as if climate scientists were unaware of such things…
Many cycles exist relating to the sun’s output of energy.. the Earth’s change in orbit, the ‘wobble’ of the Earth’s axis over time and there are more ‘internal’ cycles on Earth relating to continent formation, volcanic activity, ocean current flow changes etc but what is not cyclical (or ‘natural’) is the sudden man-made outflow of carbon dioxide.
At school, in basic science, children learn about the ‘carbon cycle’. This most awesome balance derived from life on Earth that sees carbon dioxide released by living things and bound up mainly by plants, algae and carbonate based creatures (ie shell forming creatures).
Now, ignore for the moment the human contribution to landscape change (and 7 billion of us are quickly modifying the Earth’s landscapes…forests go and agricultural landscapes develop in their place.) Sadly whole ecosystems are swept away, but the carbon cycle continues…carbon dioxide out, carbon dioxide in….
But, at the start of the Industrial Revolution, something new and unprecedented happens…..humans start mining coal, then oil then gas. This is carbon that was buried in the Earth’s crust from time periods far in the ancient past…coal beds laid down 300+ million years ago in the Carboniferous Period and oil and gas deposits laid down in the time of the dinosaurs (160 – 60 million years ago).
Remember….every drop of coal, gas and oil was once a living organism…
And what was ‘climate’ like in those periods? Many degrees warmer than now, with no polar ice and hot, steamy conditions over most of the Earth, that supported vast amounts of life albeit under some wild and violent times.
But the ‘earth’ gradually sequestered (= stored away outside the normal carbon cycle) this organic material over millions of years which allowed the benign climate we have now to exist.
Suddenly humans mine these deposits at ever increasing rates on a scale of billions of tonnes per year…using vast machines, ‘eating’ whole mountains or pumping out great reservoirs of oil and gas. The scale is mind boggling and outside any natural process or cycle. This carbon resource has been our main energy resource and has created the world society we now live in, bringing many benefits but also pollution, wars and environmental change.
My personal opinion is that major climate change has been released and there will be no concerted effort to curtail the rate of change in the future. Climate is locked in to ongoing worsening but the path will be unpredictable.
Finally, an interesting observation that confuses people and feeds the climate sceptics…How come we are also seeing records set for cold spells in both hemispheres? As the Earth spins, strong circumpolar winds develop that help to trap the cold at the poles. These winds are not uniform and circular, but rather ‘wobble’ around the globe. As the Earth’s atmosphere heats up, more energy is stored in the atmosphere and these ‘wobbles’ are becoming larger, allowing outbursts of cold air from the poles to be released into lower latitudes. This is not cooling the Earth, rather it is like someone leaving the freezer door open… Each episode of unusual blizzards or frigid air moving out from the poles is a polar heat rise, which results in more polar ice being melted as warm air moves to the poles to replace the frozen air that left.