The effects of climate change could already affect 85 percent of the world’s population, an analysis of tens of thousands of scientific studies said Monday.
A team of researchers used machine learning to capture a series of published studies between 1951 and 2018 and found about 100,000 documents and evidence of the effects of climate change on Earth systems.
“We have overwhelming evidence that climate change is affecting all continents, all systems,” study author Max Callaghan told AFP in an interview.
He added that there was a “huge amount of evidence” showing the ways in which these influences are being felt.
The researchers used a computer to identify climate-related studies, generating a list of papers on topics from intermittent butterfly migration to heat-related human deaths to changes in forest cover.
Studies rarely established a direct link to global warming – so Callaghan and teams from the Mercator Research Institute and Climate Analysis, both in Berlin, took on the task themselves.
Using location data from the studies, they divided the globe into a grid and compiled documented climate impacts that matched temperature and precipitation trends.
For each network cell they asked “is it getting hotter or colder or wetter or drier outside the bounds of natural variability?” tha Callaghan.
Then, they checked whether this type of heating matched the expectations from the climate models.
They found that 80 percent of the globe – home to 85 percent of the world’s population – had created impact studies that matched forecasts for changes in temperature and precipitation due to global warming.
Essentially, he said, research has disproportionately documented climate impacts in richer nations, with fewer studies in highly vulnerable regions.
For example he said trends in temperatures and rainfall in Africa could be linked to climate change.
“But we will not have many studies documenting the effects of those trends,” he said, calling it a “blind spot in our knowledge of climate impacts.”
Climate-related research has grown exponentially in recent decades.
Between 1951 and 1990, “we have about 1,500 studies in total,” said Callaghan, “and in the last five years since the last UN report, we have between 75,000 and 85,000 studies – a phenomenal increase.”
Callaghan said the large volume of research has made it impossible to individually identify all the studies that reliably link the observed impacts to man-made climate change.
“In the first UN climate assessment report, a team of authors could just read all the climate science,” he said. “Now you will need millions of authors.”
The machine learning technique now offers a global picture that could help experts try to synthesize a large number of studies, Callaghan said, although he added that “it can never replace human analysis.”
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