## **Overall topic/title:** Skeptical Science New Research for Week #50 2024### **First subtopic:** Regional climate change impacts#### **Content paragraphs:**- Models with high effective climate sensitivities (EffCS) are often argued to be unrealistic and should be excluded from climate change impact assessments. However, a new study finds there is no universal relationship between EffCS and projected changes in important climatic drivers of regional impacts. In fact, internal variability and processes unrelated to EffCS have similar effects on these projected changes. This suggests that model selection based solely on EffCS may be unjustified and could lead to an underestimation of climate risks.- A new study estimates that humans have caused a global increase of 1.49 degrees Celsius relative to pre-1800 baselines, with greater than 30% more certainty than alternative methods. This highlights the value of transparent, robust, and timely metrics for assessing compliance with the human-induced warming goal in the Paris Agreement.### **Second subtopic:** Climate change and biodiversity#### **Content paragraphs:**- A new study has synthesized 485 studies to produce a quantitative global assessment of climate change extinctions. With increased certainty, the results suggest that extinctions will accelerate rapidly if global temperatures exceed 1.5 degrees Celsius, potentially threatening approximately one-third of species globally.### **Third subtopic:** Climate change decarbonization strategies#### **Content paragraphs:**- A new study finds that while there is a growing consensus that transitioning to low-emissions food systems is necessary to achieve the Paris Agreement goals, most countries are not implementing sufficient actions.- Another study analyzes various carbon capture and storage (CCS) and hydrogen projects in Germany and Norway to assess potential carbon lock-ins. The findings reveal that the current setup perpetuates existing carbon lock-ins in both countries, raising concerns that this approach might entrench the energy system in a socially unjust state.- A study examines heat-related mortality in Mexico and finds 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.### **Fourth subtopic:** Climate change impacts on tourism#### **Content paragraphs:**- A new study finds that global tourism carbon emissions have grown by 3.5% per year between 2009-2019, double that of the worldwide economy, reaching 5.2 Gt CO2-e or 8.8% of total global greenhouse gas (GHG) emissions in 2019. The primary drivers of this growth are slow technology efficiency gains combined with sustained high growth in tourism demand. However, the distributional inequalities in tourism emissions are alarming, with the twenty highest-emitting countries contributing three-quarters of the global footprint.### **Fifth subtopic:** Transboundary adaptation to climate change#### **Content paragraphs:**- Climate change alters transboundary flows of water, energy, food, and people, which can lead to increased risks. Transboundary adaptation can reduce these risks by focusing interventions at the origin 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. Governance of these transboundary flows can be strengthened through a nexus approach, which considers interconnected flows' impacts on various sectors, such as hydropower affecting irrigation and/or energy needs.