Global warming now more measurable, science summit hears

New maths model takes into account GDP, gas emissions and population growth

The Niederaussem coal-fired power plant operated by German utility RWE. Photograph:   Lukas Schulze/Getty

The Niederaussem coal-fired power plant operated by German utility RWE. Photograph: Lukas Schulze/Getty


Predictions about the likely impact of global warming up to the start of the next century have become more accurate through the use of new mathematical models, the Science Foundation Ireland (SFI) science summit has heard.

Prof Adrian Raftery, a statistician and sociologist, said the model developed by his team of researchers at the University of Washington had proven to be more reliable than “scenarios” spelled out in the past by scientists under the UN intergovernmental panel on climate change.

The model, based on mathematical probabilities, takes into account trends in the economy, including gross domestic product (GDP), CO2 emissions and population growth. To test the model, the researchers used data from the 1980s to predict global warming over the following 30 years, which proved to be correct, Prof Raftery told the SFI conference on Monday in Croke Park in Dublin.

A major study published recently in Nature Climate Change analysed the past 50 years of trends in world population, per capita GDP and “carbon intensity”, (the amount of CO2 emitted for each dollar of economic activity), rather than look at how greenhouse gases will influence temperature.

The study concludes that it is extremely unlikely the planet will remain below the 2 degree threshold set by the Paris climate agreement in 2015.

The Paris accord commits to holding the average global temperature to “well below 2 degrees” above pre-industrial levels and sets an aspirational goal to limit warming to 1.5 degrees. Prof Raftery said their research shows there is a 1 per cent chance temperatures will rise by less than 1.5 degrees.

In contrast, there is a 90 per cent likelihood temperatures will rise between 2 degrees and 4.9 degrees by 2100, he added – which would have widespread detrimental impacts on the Earth.

‘Carbon Intensity’

After building a statistical model covering a range of emissions scenarios, the researchers found “carbon intensity” will be a crucial factor in future warming. Technological advances will cut global carbon intensity over the course of the century, with sharp declines in China and India. However, this decline will not be steep enough to avoid breaching the 2 degree limit as the world’s population is expected to grow to about 11 billion people by 2100, he pointed out.

This will have a relatively small impact upon temperatures as much of this growth will take place in sub-Saharan Africa, which is a minor contributor of greenhouse gas emissions, Prof Raftery said.

Prof Marcus du Sautoy, professor for the public understanding of science at Oxford University, told the summit that science had to be communicated effectively to the general public and this was a duty of all scientists. It should, he said, be made part of their job description.

Science had become controversial at the end of the 1990s because of BSE and genetically modified crops, and advances in information technology “and the perception that they were being foisted on the public”, he added.

In more recent times, “trust in science was being eaten away at again”, typified by the comment by the UK Conservative politician Michael Gove during the Brexit campaign that “we have had enough of experts”.

Scientists in the US, he believed, were behind other parts of the world in getting out of labs and communicating their science. “That is one of the reasons why science is so much under attack there,” Prof du Sautoy said. This was in contrast to Ireland, for example, where there were greater efforts to communicate science through Science Week and Maths Week, which had become the biggest maths festival in the world.

While it was very easy to talk to the converted, he had been involved with the Science Museum in London in getting 18-30 year-olds interested in science by staging “Science Lates” after the museum had closed. They involved “a lot of drinking, dancing and science” but were very successful.