Single-step attribution of increasing frequencies of very warm regional temperatures to human influence

Seasonal near-surface temperatures have increased in many regions of the World. Previous work has shown that this has led to rapidly increasing frequencies of very warm Northern Hemisphere summer temperatures. Here we show, using a 'single-step' attribution framework, that increases in frequencies of very warm seasonal temperatures, not just in Northern Hemisphere summers but in other regions and seasons, can be directly attributed to human influence. In the June-August and September-November seasons, many of the subcontinental regions of Africa and Asia show robust attributable increase in the frequencies of anomalously warm seasonal temperatures. Copyright (C) 2011 Royal Meteorological Society, Crown Copyright and Crown in the right of Canada