Nature Climate Change最新文献

Marine heatwaves (MHWs), defined as extreme ocean warming episodes, have strengthened over the past decades. High-resolution climate models improve understanding of MHWs under global warming, but such events in the future Arctic are currently overlooked. In a high-resolution climate model, we find Arctic MHWs intensify on orders of magnitude during the warming twenty-first century, following sea ice retreat. However, with little sea ice coverage, strong interannual variability emerges, which could surpass the amplitude of former intensification. Furthermore, the enhancement of MHWs correlates with an order of magnitude increase in the rate of change in the temperature anomaly. Additionally, MHWs are found to be accompanied by stratification enhancement, which could surpass interannual variability of future stratification. Such extreme temperature fluctuations combined with stratification enhancement suggest major challenges for Arctic ecosystems, and may negatively impact food webs through direct physiological temperature effects, as well as indirectly through nutrient supply and taxonomic shifts.

Charting future emissions pathways is a central tenet of IPCC assessment reports (AR), yet it is unclear how underlying drivers (including around policy and technology) have influenced the evolution of emissions pathways. Here we compare scenarios in AR5 and AR6 and find that scenarios without specific climate policies enforced have shifted lower in each scenario generation, owing to falling low-carbon technology costs and reduced expectations for economic growth, reducing fossil-fuel shares in energy and industry. Mitigation pathways consistent with 1.5–2 °C have seen increasing electrification rates and higher shares of variable renewables in electricity in more recent scenario generations, implying reduced reliance on coal, nuclear, bioenergy and carbon capture and storage, reflecting changing costs. Despite the shrinking carbon budget due to insufficient recent climate action, mitigation costs have not increased given more optimistic low-carbon technology cost projections. Moving forward, scenario producers must continually recalibrate to keep abreast of technology, policy and societal developments to remain policy relevant.

Along with employment and financial turnover, tourism has a substantial environmental footprint when added up across all aspects. Analysis of the tourism sector carbon footprint, published in 2018, showed it accounted for 8% of global emissions, with transport, shopping and food significant contributors (M. Lenzen et al. Nat. Clim. Change 8, 522–528, 2018). The study noted that the growth in global affluence was driving consumerism, and tourism is included in this growth, in fact growing at a faster rate than other areas of consumption. This growth of carbon-intensive travel was occurring faster than decarbonization. Confirming this, a recent study details that from 2009 to 2019 global tourism emissions grew at the rate of 3.5% per annum, double that of the worldwide economy (Y.-Y. Sun et al. Nat. Commun. 15, 10384; 2024).

Since 2019, the tourism industry was rocked by travel bans during the pandemic, with the industry only now returning to pre-pandemic levels. But it is important that as growth returns, it does so in a less carbon-intensive way and includes considering more than just the commonly acknowledged carbon-intensive aviation sector of tourism. This is already being seen as the world shifts to be more sustainability-focused, and the tourism industry already suffering the impacts of climate change with some classic destinations losing their appeal, for example, coastal areas at risk of extreme sea levels, as well as areas at risk of hydrological and temperature extremes.