Some of the summer temperatures in this century across much of Europe are likely to have been the warmest of the past 2 000 years, according to a study published today in Environmental Research Letters. The research is a joint effort of a group of 45 scientists from 13 countries, including a JRC expert. They used tree-ring information and historical documentary evidence to reconstruct European summer temperatures from 138 Before Common Era (BCE) to date. The new evidence provided in this study will help to better understand the climate system, its variability and extremes, and to put recent climate change into a long-term perspective.
Summer temperatures in Europe have increased by about 1.3°C over the past thirty years (1986-2015), with more severe heat waves, particularly in 2003, 2010 and 2015. The likelihood of heat waves and extremely hot summers in Europe has risen significantly in the first part of the 21st century, mainly due to anthropogenic forcing, including greenhouse gases emissions from human activities.
The results of this study show that past natural changes in summer temperatures are larger than previously thought, suggesting that current climate models may underestimate the full range of future extreme events, including heat waves. This past variability has been largely caused by large volcanic eruptions and changes in the amount of energy received from the sun.
Average summer temperatures in Europe in the 20th century were not significantly different from some earlier centuries, including the 1st, 2nd, 8th and 10th centuries Common Era (CE). However, recent summers have been unusually warm in the context of the past two millennia, and at no time have temperatures been so high over a 30-year period than in the past 30 years (1986-2015 CE). This finding supports the conclusions reached by the Intergovernmental Panel on Climate Change (IPCC) that recent warming is mainly caused by anthropogenic activity.