Climate science and impacts

Is the climate changing?

Climate Change is happening, and human emissions are the major contributor. Today we are as certain that climate change is occurring due to fossil fuels and carbon emissions as we are that cigarettes cause lung cancers.

Doesn’t a cold winter provide there’s no global warming?

No. Extreme weather of all kinds is actually made more likely by global warming.

For the 2013-14 North American winter, the “polar vortex” of very cold air has strayed south. This seems to be because global warming has reduced the air pressure differences that we can usually rely on to keep this vortex at home near the North Pole. Look up the short video from President Obama’s chief scientific advisor explaining it.

Are the seas really rising?

Yes, the seas are rising. Measurements over the last century showed slow but steady rises. This has been too slow to see happening, but it has still been serious.  Unfortunately, newer predictions, including more accurate satellite measurements, and allowing for melting glaciers and icecaps, are for faster and worse sea level rises.

The World Meteorological Organisation advises that sea levels are now rising about twice as fast as they did on average across the 20th century.  If emissions continue to increase unabated, sea level could rise by 1 metre or more by 2100. Sustained warming could eventually lead to the loss of the entire Greenland ice sheet, with a rise in sea level of up to 7 metres. And release of the methane currently trapped in the Arctic permafrost could lead to far worse results still.

Even a small rise in sea levels will give a higher base for tides, let alone for storms or cyclones. Some countries – and some of Australia’s coasts – don’t have much more than a metre above sea level. Kakadu’s freshwater wetlands and the tourist industry based on them are very vulnerable, for example. Local governments like Hobart plan on the basis that 3 metres of freeboard above average sea level is needed before an area can be said to be above the effects of storm surges and king tides.

Climate change creates sea level rises because water expands as it heats (from 4oC upwards). And the oceans are absorbing more heat as global warming occurs.  We know now that over 90% of global warming is going into the oceans. On top of that, glaciers and ice sheets are melting and sliding into the sea.

But hasn’t this always occurred?

Science tells us that Earth’s climate has changed over millions of years, due to things like the very slow drift of continents. The Earth has seen species come and go with this. We’ve seen smaller fluctuations from time to time and place to place in the (much briefer) course of human history.

However the changes we are seeing today are large and rapid global changes, drastically exceeding the rate of change seen before.

Despite many climate deniers claiming global warming stopped around 1998 this is far from true. See the explanation from the World Bureau of Meterology here says no.

As Professor Ross Garnaut said in the2011 update to his Report:

There is a statistically significant warming trend, and it did not end in 1998 or in any other year. Every year since 1976 has been above average. If you were born in 1976 or later, you’ve never lived in a below average year. 2013 was Australia’s hottest since records began (confirmed by Australia’s Bureau of Meteorology) and the world’s 4th hottest.

Is climate change causing more frequent and extreme weather events?

Overall, yes. While we can’t say any individual storm was caused by global warming, it’s basic physics that more energy in weather systems can be expected to produce more severe weather events.

Doesn’t CO2 and other greenhouse gases make up only a tiny part of the atmosphere?

The fact that CO2 is only a small proportion of Earth’s total atmosphere, is exactly why changes in the amount of CO2 being emitted since the Industrial Revolution are able to have a significant effect on this proportion.


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