The half-degree Celsius increase in the Earth's core temperature as a result of global warming was enough to spark major heat waves and torrential downpours in regions around the world, researchers reported on Friday.
Comparative data taken over 40 years, from 1960 to 1979 and from 1991 to 2010, indicates that average global temperatures have increased 0.5 degrees Celsius, leading scientists to discover that several forms of extreme weather patterns have gained intensity and increased in duration.
The earth's hottest summer temperatures increased by more than 1 degree Celsius across a quarter of the Earth's landmass while the coldest winter temperatures increased more than 2.5 degrees Celsius.
Precipitation has also increased in terms of intensity and duration, up nearly 10 percent across a quarter of all landmasses. On the other hand, the duration of hot spells which can fuel devastating forest fires, lengthened by a week across half of the earth's landmasses.
These changes point to global climate changes that exceed well outside of the boundaries of natural variability, according to a study published in the Journal of Natural Climate Change.
"We have to rely on climate models to predict the future," said lead author Carl-Friedrich Schleussner, a researcher at the Potsdam Institute of Climate Impact Research.
"However, given that we now have the observational evidence of a roughly 1 degree Celsius warming, we can also look at the real-life impacts this has brought," he said in a statement.
According to science, observed trends are generally seen as more reliable than projections, which can vary greatly, depending on the assumptions made.
Changes in climate - sometimes defined as "average weather" patterns - can only be identified across time periods measured in decades or longer.
0.5 Celsius 'does matter'
Global warming caused mostly by the burning of fossil fuels began slowly in the early 19th century with the onset of industrialization but has accelerated rapidly over the last 50 to 60 years.
The 196-nation Paris Agreement, penned in the French capital in 2015, vowed to cap the rise of the planet's average surface temperature at "well under" 2 degrees Celsius, and to "pursue efforts" to block it at 1.5 degrees Celsius.
To inform that effort, the Intergovernmental Panel on Climate Change (IPCC) - the U.N.'s top science advisory group - will issue a report for policy makers in September 2018 on the feasibility of the 1.5 degree Celsius target, as well as what negative impacts might be avoided if it is met.
The new study - one of thousands that will be reviewed by the IPCC - suggests that even a half-degree rise in the earth's temperature is significant.
"With the warming the world has already experienced, we can see very clearly that a difference of 0.5 degree Celsius really does matter," said co-author Erich Fischer, a scientist at ETH Zurich in Switzerland.
Earlier research based on computer models, also led by Schleussner, concluded that warming of 2 degrees Celsius would, compared to 1.5 degree Celsius, double the severity of crop failures, water shortages and heatwaves in many regions of the world.
The findings also indicate that keeping the temperature increase at or below 1.5 degrees Celsius would give coral reefs - considered the cornerstones of the ecosystems which sustain .5 billion people worldwide and one-fourth of all marine wildlife - a fighting chance to adapt to warmer, more acidic seas.
An additional half-degree increase in the Earth's temperature, but could expose the majority of coral reefs to possible extinction by century's end.