## Climate Change Research Highlights### Regional Impacts Assessment- Climate risk assessments should consider a wide range of possible futures, but scientists often use simulations from multiple global climate models to explore potential changes in regional climates and their impacts.- Some of the latest-generation models have high effective climate sensitivities. It has been argued these "hot" models are unrealistic and should therefore be excluded from analyses of climate change impacts.- Here, we show there is no universal relationship between EffCS and projected changes in a number of important climatic drivers of regional impacts.- Even when a correlation is found, internal variability and processes unrelated to EffCS have similar effects on projected changes in the climatic drivers as EffCS.- Model selection based solely on EffCS appears to be unjustified and may neglect realistic impacts, leading to an underestimation of climate risks.### Global Warming Estimates- Assessing compliance with the human-induced warming goal in the Paris Agreement requires transparent, robust and timely metrics.- Linearity between increases in atmospheric CO2 and temperature offers a framework that appears to satisfy these criteria, producing human-induced warming estimates that are at least 30% more certain than alternative methods.- For 2023, we estimate humans have caused a global increase of 1.49 ± 0.11°C relative to a pre-1700 baseline.### Biodiversity Extinction Projections- Climate change is expected to cause irreversible changes to biodiversity, but predicting those risks remains uncertain.- I synthesized 485 studies and more than 5 million projections to produce a quantitative global assessment of climate change extinctions.- With increased certainty, this meta-analysis suggests that extinctions will accelerate rapidly if global temperatures exceed 1.5°C.- The highest-emission scenario would threaten approximately one-third of species, globally.- Amphibians; species from mountain, island, and freshwater ecosystems; and species inhabiting South America, Australia, and New Zealand face the greatest threats.- In line with predictions, climate change has contributed to an increasing proportion of observed global extinctions since 1970.- Besides limiting greenhouse gases, pinpointing which species to protect first will be critical for preserving biodiversity until anthropogenic climate change is halted and reversed.### Carbon Capture and Storage- The global energy landscape is entrenched in fossil fuels, shaping modern life profoundly. Germany, a prominent example, grapples with transitioning from its fossil-fuelled infrastructure despite governmental support for decarbonization.- Carbon capture and storage (CCS) and hydrogen appear as crucial tools in this transition.- A recent partnership between Germany and Norway seeks to leverage Norway's CCS and hydrogen expertise to aid Germany's decarbonization efforts.- However, CCS faces criticism for potential mitigation deterrence and carbon lock-ins, perpetuating fossil fuel reliance.- This study critically analyses the Norwegian-German CCS-Hydrogen-Nexus, focusing on potential carbon lock-ins.- By examining specific projects, institutional frameworks, and industry involvement, we aim to elucidate the partnership's implications for carbon lock-ins.- This critical case holds significance for Europe's largest economy and offers insights applicable to CCS technology globally.- We find that the current setup perpetuates existing carbon lock-ins both in Germany and Norway.- Central problems are the interchangeability of blue and green hydrogen, asset specificity of pipeline and pumping infrastructure and the central role which actors from the fossil fuel industry play in the rollout of the CCS-Hydrogen-Nexus.- Our concern is that this approach might entrench the energy system in a socially unjust state.- EU policy on blue hydrogen emerged as a factor that helps to avoid carbon lock-ins.### Heat and Young Mortality- Recent studies project that temperature-related mortality will be the largest source of damage from climate change, with particular concern for the elderly whom it is believed bear the largest heat-related mortality risk.- We study heat and mortality in Mexico, a country that exhibits a unique combination of universal mortality microdata and among the most extreme levels of humid heat.- Combining detailed measurements of wet-bulb temperature with age-specific mortality data, we find that younger people are particularly vulnerable to heat: People under 35 years old account for 75% of recent heat-related deaths and 87% of heat-related lost life years, while those 50 and older account for 96% of cold-related deaths and 80% of cold-related lost life years.- We develop high-resolution projections of humid heat and associated mortality and find that under the end-of-century SSP 3−7.0 emissions scenario, temperature-related deaths shift from older to younger people.- Deaths among under-35-year-olds increase 32% while decreasing by 33% among other age groups.### Tourism Industry Carbon Footprint- Tourism has a critical role to play in global carbon emissions pathway. This study estimates the global tourism carbon footprint and identifies the key drivers using environmentally extended input-output modelling.- The results indicate that global tourism emissions grew 3.5% p.a. between 2009-2019, double that of the worldwide economy, reaching 5.2 Gt CO2-e or 8.8% of total global GHG emissions in 2019.- The primary drivers of emissions growth are slow technology efficiency gains (0.3% p.a.) combined with sustained high growth in tourism demand (3.8% p.a. in constant 2009 prices).- Tourism emissions are associated with alarming distributional inequalities. Under both destination- and resident-based accounting, the twenty highest-emitting countries contribute three-quarters of the global footprint.- The disparity in per-capita tourism emissions between high- and low-income nations now exceeds two orders of magnitude.- National tourism decarbonisation strategies will require demand volume thresholds to be defined to align global tourism with the Paris Agreement.### Transboundary Climate Change Adaptation- Climate change alters transboundary flows that are essential for people and nature, including flows of water, people, energy, and food.- Transboundary adaptation can reduce risks by focusing interventions at the origin or source of the climate change impact, along transmission channels, and in the destination country or region.- Anticipating, planning for, and managing flows across geographic and sectoral boundaries builds resilience across interconnected systems and populations.- Transboundary adaptation is strengthened and more effective when using a nexus approach, which considers how interconnected flows such as hydropower changes affect irrigation and/or energy needs.- Greater recognition of governance of transboundary flows within adaptation planning can better identify and manage systemic vulnerabilities that escalate climate change risk.- Strengthening governance frameworks to improve cross-border cooperation must be done in conjunction with addressing critical dimensions of vulnerability and promoting the integrated management of shared resources.