Global warming began earlier than previously thought and can be traced back to the 1830s – during the industrial revolution – according to new research published today.
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Co-author Dr Helen McGregor of the University of Wollongong’s School of Earth and Environmental Sciences said the results were both unexpected and extraordinary.
Dr McGregor said the research, published in the journal Nature, shows how quickly the Earth’s climate responds to a change in the atmosphere, even with industrialisation spreading to only a limited degree by the early 1800s.
The change was relatively small but it was “significant and sustained” – and reversed a trend of global cooling which had been happening until that point.
“That’s a very interesting finding – that a small amount of industry can have a significant impact,” Dr McGregor said.
“I think it really tells us that the climate responds very quickly.
“When we look at the global warming we’ve had so far, the general message is that we’ve just crossed the 1 degree warming threshold. But that’s relative to the 1880s, whereas our study shows that warming was going on for a good while before that.”
That’s a very interesting finding – that a small amount of industry can have a significant impact
- Dr Elizabeth McGregor
The international research team used palaeoclimate records – including fossils and air bubbles found deep inside ice cores – to analyse when the “sustained and significant” change in global temperatures could first be identified.
Air bubbles trapped in ice cores showed carbon dioxide (CO2) levels of about 280 parts per million in the 1830s. This increased to about 295ppm by 1895. Today the level is about 403ppm.
In the northern hemisphere and tropical oceans, the warming happened at the same time as the increase in pollutants in the atmosphere caused by the rapid industrialisation which gained pace by the early 1800s.
Warming in the southern hemisphere was delayed, which may be associated with the sheer volume of ocean south of the equator.
The records studied came from sources including coral, cave formations, sediment layers and ice cores.