The only real climate change debate amongst scientists is about the consequences, says Peter McCallum of Mackay Conservation Group.

The only real climate change debate amongst scientists is about the consequences, says Peter McCallum of Mackay Conservation Group. Gerald Herbert

THERE'S debate in the Daily Mercury's letter pages about climate change but the world's top climate scientists are in agreement that it's both real and that humans are the cause.

Over the past decade many studies have examined peer-reviewed scientific papers on the subject of climate change.

They have found that 97 to 98 per cent of climate scientists agree that climate change is happening and caused by human activity.

The only real debate amongst scientists is about the consequences.

Way back in 1896, Swedish physicist Svante Arrhenius developed a mathematical equation that showed a link between the concentration of carbon-dioxide in the atmosphere and heat at the Earth's surface.

Since then the scientific community has known the impact of increased carbon-dioxide concentration.

Arrhenius, being a Swede, thought the greenhouse effect would be a good thing.

He lived in a country with large areas within the Arctic Circle which were too cold and dark to grow crops most of the year.

He thought that temperature increase would make Sweden more habitable but maybe that was a superficial argument.

Fast forwarding to July, 2018, Sweden had to call for international support as wildfires swept through its forests.

Record temperatures and a long period without rain caused the fires. That's one of the consequences of global warming that Arrhenius probably didn't have in mind.

Physicists know how carbon-dioxide molecules are able to act like climate blankets when other molecules such as nitrogen and oxygen do not.

That helps scientists build models of climate change that can be tested against evidence in the real world. It's unfortunate for us that there is plenty of evidence to test climate models with.

Land and ocean temperature measurements, changing plant growing seasons and rainfall and flood patterns, all point to increasing climate change.

On top of that, almost every glacier on earth is shrinking.

Here in Queensland, the Great Barrier Reef has been subjected to five bleaching events since 1998.

Before then, coral bleaching was a localised issue that only happened where small bodies of water became too hot and killed the coral organisms within it.

The Bureau of Meteorology says that 2019 could be a record hot year for Australia - even more bad news for the reef.

It's clear climate change is caused by carbon-dioxide and it's humans producing it.

Peter McCallum is the coordinator of Mackay Conservation Group