Heat and rainfall extremes have intensified over the past few decades and this trend is projected to continue with future global warming 1-3. A long persistence of extreme events often leads to societal impacts with warm-and-dry conditions severely affecting agriculture and consecutive days of heavy rainfall leading to flooding. Here we report systematic increases in the persistence of boreal summer weather in a multi-model analysis of a world 2 °C above pre-industrial compared to present-day climate. Averaged over the Northern Hemisphere mid-latitude land area, the probability of warm periods lasting longer than two weeks is projected to increase by 4% (2-6% full uncertainty range) after removing seasonal-mean warming. Compound dry-warm persistence increases at a similar magnitude on average but regionally up to 20% (11-42%) in eastern North America. The probability of at least seven consecutive days of strong precipitation increases by 26% (15-37%) for the mid-latitudes. We present evidence that weakening storm track activity contributes to the projected increase in warm and dry persistence. These changes in persistence are largely avoided when warming is limited to 1.5 °C. In conjunction with the projected intensification of heat and rainfall extremes, an increase in persistence can substantially worsen the effects of future weather extremes. Extreme weather events are commonly analysed in terms of intensity or frequency but often it is their persistence that leads to the most severe effects. Extended periods of warm and dry weather can strongly affect human health and agriculture and increase risks of wildfires 4. In 2018, dry and warm conditions in western Europe extended from April to September with only a few short interruptions of cooler and rainy weather 5-7 (see Fig. 1). This persistent drywarm compound extreme had a devastating effect on agriculture in Germany, with wheat harvests down by 15% (ref. 6). Similarly, most damaging flooding events occur following several consecutive days of heavy rainfall 8. In 2016, a slow-moving low-pressure system remained over Europe for two weeks, resulting in several days of heavy precipitation leading to floods in many municipalities in western Europe 9 (Fig. 1). Global warming is already increasing the frequency and intensity of heat and rainfall extremes 3 , as well as the duration of heat waves 10 , and these trends are projected to continue with future warming 11. However, if and how changes in persistence of local weather conditions might contribute to more severe weather extremes is poorly understood. Some observational studies suggest that summer persistence has increased over recent decades 12-16 but this is so far not supported by modelling studies.

An ever-growing body of evidence suggests that climate change is already impacting human and natural systems around the world. Global environmental assessments assessing this evidence, for example by the Intergovernmental Panel on Climate Change (IPCC) 1 , face increasing challenges to appraise an exponentially growing literature 2 and diverse approaches to climate change attribution. Here we use the language representation model BERT to identify and classify studies on observed climate impacts, producing a machine-learning-assisted evidence map which provides the most comprehensive picture of the literature to date. We identify 100,724 (62,950 − 162,838) publications covering a broad range of impacts in human and natural systems across all continents. By combining our spatially resolved database with human-attributable changes in temperature and precipitation on the grid cell level, we infer that attributable climate change impacts may be occurring in regions encompassing 85% (80%) of the world's population (land area). Our results also reveal a substantial 'attribution gap' as robust evidence for attributable impacts is twice as prevalent in high income compared to low income countries. While substantial gaps remain on con dently establishing attributable climate impacts at the regional and sectoral level, our unique database illustrates the broad extent to which anthropogenic climate change may already be impacting natural systems and societies across the globe. MainThere is overwhelming evidence that the impacts of climate change are already being observed in human and natural systems 3 . These effects are emerging in a range of different systems and at different scales, covering a broad range of research elds from glaciology to agricultural science, and marine biology to migration and con ict research 1 . The evidence base for observed climate impacts is expanding 4 , and the wider climate literature is growing exponentially 5,6 . Systematic reviews and systematic maps offer structured ways to collectively identify and describe this evidence while maintaining transparency, attempting to ensure comprehensiveness and reduce bias 7 . However, their scope is often con ned to very speci c questions covering no more than dozens to hundreds of studies.In the climate science community, evidence-based assessments of observed climate change impacts are performed by the Intergovernmental Panel on Climate Change (IPCC) 1 . Since the rst Assessment Report (AR) of the IPCC in 1990, we estimate that the number of studies relevant to observed climate impacts published per year has increased by more than two orders of magnitude (Fig. 1a). Since the third AR, published in 2001, the number has increased ten-fold. This exponential growth in peer-reviewed scienti c publications on climate change 5,6 is already pushing manual expert assessments to their limits. To address this issue, recent work has investigated ways to handle big literature in sustainability science by scaling systematic review and map methods to large bodies ...