|July 25, 2019|
Scientists debunk claim that global warming is a natural phenomenon
|The speed of global warming has never been as high as it is today, according to the findings of three new studies carried out by teams of scientists from across the globe. |
The research cites man-made emissions as the overwhelming cause of the Earth's warming, revealing the profound impact humans are having on the climate.
"Global warming is happening at an extensive rate and it is caused primarily by human emissions," Dr Benjamin Henley, the only Australian scientist involved in the research, told SBS News.
Not a natural phenomenon
The scientists from eight countries spent thousands of hours assessing global patterns of climate variability, finding that the average global temperature in the 20th Century and beyond is higher than at any time in the past 2000 years.
The studies suggest that modern climate change is not caused by natural phenomena, as it was in the 2000 years prior to the industrial era.
"For example the Little Ice Age, or the Medieval Climate Anomaly - natural factors have caused those," said Dr Henley, who is a researcher Melbourne University's School of Earth Sciences.
"But one of the important things that the studies showed, is that the spatial extent, in other words how far around the world these warmings and coolings actually occurred, was not very coherent, it was not the same everywhere."
In other words, before the 20th century, temporary warming and cooling events did not occur simultaneously across the globe as they are today.
Dr Henley said the speed of the earth's warming is another indicator that natural factors are not the cause.
"The changes that we are seeing now are happening in just a few short decades, it's so much faster and it's so much stronger and it has so much spatial extent."
"We have human emissions driving up temperatures and we see a very clear and coherent and consistent pattern around the world, covering 98 per cent of the planet."
Before human-induced climate change
The research also counters previous theories that temperature fluctuations in the last 2000 years were caused variations in the Sun, finding instead that volcanoes were largely responsible.
"Part of this study was to look at what drove the decade-to-decade changes in global temperature over the last 2000 years, before human emissions starting driving up temperatures," Dr Henley said.
"What we found is that major volcanoes have a really important impact on the climate, they cool the climate temporarily and then there is a recovery of global temperature shortly after that cooling effect.
"And that was important in the last 2000 years," he said.
But he said these effects are now dwarfed by human-driven climate change.
"When the industrial revolution really took hold, it became much clearer the impact humans have on driving temperature."
Dr Henley said the research reveals the urgency for a more concerted, global effort to addresses climate change.