Search Climate Insights Directory

The document explains 'event attribution' as a scientific method to determine how much human-induced climate change affects the probability and intensity of specific weather extremes. It provides a detailed breakdown of how climate change influences heatwaves, floods, tropical cyclones, snowfalls, droughts, and wildfires, while cautioning against oversimplifying these events as having a single cause. The guide emphasizes that while some trends (like heatwaves) are globally certain, others (like floods or droughts) vary by region and are influenced by local human factors such as land use and water management.

The authors used the delta method to reduce model biases by calculating monthly anomalies relative to a 1991-2020 reference period, then added observed averages from the Applied Climate Information System (ACIS) to derive absolute temperature values. They focused on two Shared Socioeconomic Pathways (SSP1-2.6 and SSP3-7.0) to represent low and high carbon emission scenarios, respectively, applying a rolling 10-year average to smooth the time series for 247 specific locations.

The report analyzes the transition to virtual meetings for the Inter-American Institute for Global Change Research (IAI) during the COVID-19 pandemic. It finds that while virtual formats increased participation and reduced costs, they hindered informal networking. Survey results indicate a high level of satisfaction with the organization of CoP-29, though there is a noted need for better introductory materials for new participants and more frequent communication between sessions via Zoom and newsletters.

A rapid analysis of the June 2021 Pacific Northwest heatwave concludes that the event was virtually impossible without human-caused climate change. The study estimates the event as a 1-in-1000-year occurrence in the current climate, noting it was approximately 2°C hotter than it would have been before the industrial revolution. Projections indicate that with 2°C of global warming, such events could occur every 5 to 10 years.

The Climate Action Tracker (CAT) reports that a wave of net zero pledges from 127 countries could reduce projected warming by 2100 to as low as 2.1°C. However, current policies still put the world on a trajectory of 2.9°C, and a significant emissions gap remains for 2030.

Ember argues that National Grid ESO's FES 2020 scenarios for achieving net-zero by 2050 are undermined by an over-reliance on BECCS to offset residual emissions. The briefing highlights that the required scale of BECCS would necessitate converting 1Mha of UK agricultural land to energy crops and potentially 200Mha globally, posing significant risks to biodiversity and food security. Ember contends that the assumption of 'instant' negative emissions is flawed and that relying on BECCS creates a moral hazard, potentially discouraging more ambitious decarbonisation efforts in difficult sectors like aviation and agriculture.

The report concludes that the prolonged regional heat in Siberia from January to June 2020 was effectively impossible without human influence, with a best estimate probability ratio of 99,000 compared to a 1900 climate. Such events would have been at least 2°C cooler without anthropogenic influence. For the specific record of 38°C at Verkhoyansk, the study found a confident anthropogenic shift in intensity of 1.5°C, although the probability ratio for this specific station event is of lower confidence. By 2050, the regional heat is expected to be further intensified, with a synthesis change in intensity of 4.85°C compared to 1900.

The document outlines the critical role of up-to-date data in understanding Earth processes and managing climate risks. It highlights the use of LiDAR for flood mapping via the 3-Dimensional Elevation Program, the importance of NOAA's hydrologic and coastal data, and the role of the Earth Prediction Innovation Center in extreme weather forecasting. It also emphasizes the value of NASA and NOAA's planetary-scale satellite observations and the potential for artificial intelligence to enhance disaster prediction and community resilience through the proposed National AI Initiative.

The Malawi National Adaptation Plan (NAP) Framework provides a structured approach to building climate resilience, integrating adaptation into national development planning, and coordinating stakeholders. It outlines five key mandates: improving community resilience through agriculture and disaster risk management, sustainable natural resource use, improving soil and land management, conserving biodiversity, and providing policy advocacy. The framework adopts a systems approach and emphasizes vertical and horizontal integration, community participation, and gender-responsiveness. It identifies critical gaps in climate modelling and institutional capacity, proposing a roadmap that includes risk and vulnerability assessments, the mobilization of private sector finance, and the integration of adaptation priorities into ministry spending plans, with support from the Green Climate Fund.

The Union of Concerned Scientists projects that without reductions in carbon emissions, US military installations will face a significant increase in days with a heat index above 100°F by midcentury, potentially increasing the rate of heat-related illnesses (HRIs). The report highlights that basic training recruits are particularly vulnerable and that installations in Florida are projected to be among the most affected. To address these risks, the memo recommends increased funding for HRI research, the establishment of an expert working group, improved training on acclimatization, and a transition toward renewable energy to limit future warming.

The study finds that the extreme two-day rainfall during Tropical Storm Imelda in September 2019 was made more likely and more intense by anthropogenic climate change. Observational data suggests the probability of such an event has increased by a factor of 2.6 since 1900, while climate model synthesis indicates a probability increase of 1.5 to 3.1 times and an intensity increase of 9% to 21%. The report also notes that rapid urban expansion and loss of impervious cover in Southeast Texas have exacerbated flooding risks for approximately 6.6 million people in the impacted counties.

The document argues that while NDCs (short-to-medium term commitments) and LTSs (mid-century visions) serve different legal and functional roles, they should be developed synergistically. Aligning them prevents the 'lock-in' of carbon-intensive infrastructure and reduces administrative costs by sharing data, modeling, and stakeholder consultations. The authors suggest that ideally, an LTS should inform the NDC, though they provide options for countries developing both in parallel or those updating NDCs without a formal LTS.

The document presents a collection of 36 internal and public documents from 1963 to 2017, detailing how the oil industry—specifically Exxon, Shell, Mobil, and the American Petroleum Institute (API)—understood the link between fossil fuels and global warming decades ago. It argues that despite internal consensus on the potential for 'catastrophic' impacts, these companies pivoted in the late 1980s to a strategy of manufacturing doubt, funding denier groups, and misleading the public and policymakers to protect their business models.

The report argues that climate change is a vital national security risk that requires a whole-of-government response. It proposes a 'Climate Security Plan for America' structured around four pillars: demonstrating leadership through a new White House Office on Climate Security, assessing risks via a Climate Security Crisis Watch Center, bolstering international resilience to compete with adversaries like China and Russia, and building domestic infrastructure resilience. The plan emphasizes the need for the U.S. to remain in the Paris Agreement and to integrate climate foresight into military doctrine and intelligence assessments.

The analysis concludes that human-induced climate change has made the June 2019 heatwave in France more likely and more intense. Observational data suggests that a heatwave of this intensity is occurring at least 10 times more frequently today than a century ago, with temperatures approximately 4C higher. While climate models qualitatively agree on the strong human influence, they show smaller trends and fewer severe heatwaves than observations, simulating a probability increase of between a factor of 2 and 20. The study emphasizes that early-season heatwaves in June have more severe health and organizational impacts than mid-summer events.

The World Weather Attribution (WWA) consortium investigated the possibility of analyzing the effect of climate change on Super Typhoon Mangkhut's rainfall but determined an analysis was not feasible. The decision was based on three primary constraints: the availability of only one high-resolution model for the region, poor quality of public observational data in the affected area (with 50% missing data in most stations), and a lack of manpower and stable funding. The document notes that while greenhouse gases are expected to increase the precipitation of the strongest storms globally, region-specific projections have low confidence. Additionally, the WWA stated that while sea level rise affects storm surges, such impacts are not currently part of their attribution assessments.

The study assesses the 2018 heatwave in Northern Europe using observational data and climate models to determine the role of human-induced warming. It finds that the probability of such an event has increased across the region, with the most significant increases in probability estimated in Ireland, Denmark, and the Netherlands. While the heat was most extreme in the high Arctic (northern Finland), where it exceeded historical records, the risk ratio was more easily quantified in southern regions. The authors conclude that anthropogenic climate change made these heatwaves more likely, though the exact magnitude of the increase is harder to quantify in Scandinavia due to high natural variability.

In early July 2018, southwestern Japan experienced extreme rainfall, with some interior stations recording more than twice the usual amount for the wettest day of the year, leading to local return times exceeding 200 years. Observational data from 94 stations show a higher prevalence of positive trends in extreme rainfall probability than negative trends, suggesting a systematic influence beyond natural variability. While a single high-resolution model (EC-Earth T799) qualitatively reproduces these positive trends from 1850 to 2098, the authors state that a lack of sufficient climate models and manpower prevents a robust quantitative attribution statement. The analysis concludes that climate change likely increased the probability of such extreme rains, though the exact magnitude remains undetermined.

An international team of scientists used a multi-method attribution approach to determine that anthropogenic climate change increased the likelihood of the 2015-2017 Western Cape drought by a factor of 3.3. The drought, characterized by three consecutive years of below-average rainfall, led to a severe water crisis in Cape Town, nearly resulting in 'day zero'. The study finds that drought risk in this region scales linearly with warming, suggesting that further temperature increases will continue to raise the probability of such extreme events.

The study concludes that human-induced climate change had no significant influence on the occurrence of Storms Eleanor and Friederike. While observational data from the past 40 years show a decrease in near-surface wind speeds, climate models suggest a marginal increase in the probability of extreme hourly winds (0-20%) by the middle of the century due to greenhouse gases. The observed decline in storminess is attributed to factors other than climate change, such as increased surface roughness, aerosols, and decadal variability.