By measuring the width, colour and other properties of the rings, researchers said the climate in Central Asia was altered in irreversible fashion against a background of constant heat waves in the 1990s.The unprecedented rise in average temperatures over the years led to a ripple of repetitive processes of drying out the soil – which contributed to a rise in temperatures.

Earlier assessments by the company suggested that the peak would be achieved by 2030.

Senior government and EU officials and scientific and industry experts discussed proposals to expand the use of hydrogen at an online forum dubbed The European Hydrogen Week.