But the effects are not confined to the Northern Hemisphere. Prof Anastasios Tsonis, head of the University of Wisconsin Atmospheric Sciences Group, has recently shown that these MDOs move together in a synchronised way across the globe, abruptly flipping the world’s climate from a ‘warm mode’ to a ‘cold mode’ and back again in 20 to 30-year cycles.
'They amount to massive rearrangements in the dominant patterns of the weather,’ he said yesterday, ‘and their shifts explain all the major changes in world temperatures during the 20th and 21st Centuries.
'We have such a change now and can therefore expect 20 or 30 years of cooler temperatures.’