Why did scientists initially dismiss 'hot' climate models?

Scientists initially dismissed models showing higher climate sensitivity (above 5°C) because they seemed incompatible with historical climate data (paleoclimate data), which suggested a lower sensitivity range of 2.6-3.9°C.

What is the major difference in the 'hot' climate models?

The key difference lies in how these 'hot' models describe the physical processes within clouds, particularly concerning the supercooled phase of water. Getting cloud physics correct is a significant challenge in climate modeling.

How reliable is the paleoclimate data used to validate models?

The speaker questions the reliability of using paleoclimate data for clouds, as direct observations from millions of years ago are non-existent. It requires assuming current cloud behavior accurately reflects past conditions, which is a significant 'if'.

What evidence suggests the 'hot' models might be correct?

A study using a 'hot' UK Met Office model for short-term weather forecasting found it produced better predictions than an older, 'colder' version. Additionally, the Hanson et al. paper re-analyzed historical data, finding compatibility with higher climate sensitivity.

What are the potential consequences of a high climate sensitivity?

High climate sensitivity could lead to regions around the equator becoming uninhabitable within decades, causing mass migration, famine, drought, political tensions, pandemics, economic collapse, and a significant reduction in the global population.

What solutions does the speaker propose for climate change?

The speaker's wish list includes pricing carbon dioxide emissions, expanding renewables, investing in nuclear power, accepting carbon removal technologies, and abandoning ineffective protest methods like 'gluing yourself to things'.

What is Planet Wild and how can one contribute?

Planet Wild is a community-based organization restoring ecosystems and protecting wildlife. Contributions fund projects like reforestation and sea turtle protection. Individuals can become nature supporters starting at $6/month.

Key Moments

I wasn't worried about climate change. Now I am.

Sabine Hossenfelder

Science & Technology4 min read22 min video

Jan 27, 2024|2,335,232 views|156,735|31,632

science without the gobbledygoook hossenfelder climate climate change climate science climate models climate sensitivity climate models vs reality climate models vs observations what is climate sensitivity hot models hot models problem

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Key Moments

TL;DR

Climate sensitivity may be higher than assumed, leading to faster warming and severe global consequences.

Key Insights

Recent warming trends and record-breaking temperatures in 2023 highlight the urgency of climate change, possibly exacerbated by reduced ocean pollution.

Climate sensitivity (ECS) measures a model's temperature response to doubled CO2; the range has been debated, with some models indicating much higher sensitivity than previously thought.

The 'hot models' with higher ECS are often dismissed due to seeming incompatibility with paleoclimate data, but this dismissal may be flawed.

Discrepancies in cloud physics, particularly supercooled water, are a key factor in differentiating 'hot' and 'cold' climate models.

Evidence suggests 'hot' models might be more accurate for short-term weather forecasting, challenging the reliance on paleoclimate data alone.

A higher ECS implies a faster timeline for severe impacts like widespread crop failure, mass migration, political instability, and economic collapse.

Effective climate action requires policy changes like carbon pricing, renewable energy expansion, nuclear power, and carbon removal, not just technological fixes.

Community-based conservation efforts like Planet Wild offer a tangible way for individuals to contribute to ecosystem restoration and climate mitigation.

THE INCREASINGLY URGENT REALITY OF CLIMATE CHANGE

The year 2023 marked a new record for global average temperatures, accompanied by longer and hotter heatwaves, record low Antarctic sea-ice extent, and rising ocean temperatures. While natural cycles like El Niño and potential effects of reduced ship pollution might temporarily influence year-to-year variations, the overall trend points towards a steep and rapid deterioration of the climate situation. This escalating warming trend compels a closer examination of the underlying scientific parameters that govern climate projections.

UNDERSTANDING CLIMATE SENSITIVITY (ECS)

Climate sensitivity, specifically Equilibrium Climate Sensitivity (ECS), quantifies the temperature increase expected when atmospheric carbon dioxide doubles from pre-industrial levels, assuming the climate system reaches equilibrium. While this doubling doesn't occur naturally, ECS is a crucial metric for understanding how rapidly global temperatures will rise with continued CO2 emissions. The range of ECS values derived from climate models is critical for policy-making and assessing the speed of future warming.

THE "HOT MODELS" PROBLEM AND PALEO-CLIMATE DATA

Leading climate models, compiled in projects like CMIP, previously estimated ECS between 2 and 4.5 degrees Celsius. However, a 2019 assessment revealed some models ('hot models') predicted ECS above 5 degrees Celsius. Climate scientists initially dismissed these 'hot models,' arguing their high sensitivity was incompatible with paleoclimate data, studies of past climates from millions of years ago. A 2020 study aggregating this paleoclimate data suggested a lower ECS range (2.6-3.9°C), reinforcing the exclusion of 'hot models' from IPCC reports.

CHALLENGING THE RELIANCE ON PALEO-CLIMATE DATA

The core difference between 'hot' and 'cold' models lies in their simulation of cloud physics, particularly the behavior of supercooled water. While paleoclimate data is used to validate models, it lacks direct information on cloud behavior from millions of years ago. This necessitates an assumption that current cloud physics models are applicable to past conditions, a significant assumption given the cloud physics themselves are the point of contention. Critiques question whether this methodology provides a reliable basis for dismissing models that perform better under current observable conditions.

THE CASE FOR 'HOTTER' MODELS THROUGH WEATHER FORECASTING

A compelling piece of evidence emerges from weather forecasting, where climate models can be tested against real-world observations over shorter timescales. The UK Met Office adapted one 'hot' model for 6-hour weather forecasts, finding it produced more accurate predictions than an older, 'colder' version of the same model. This suggests that models with higher climate sensitivity may better represent atmospheric processes, casting doubt on the outright dismissal based solely on paleoclimate data compatibility. If these 'hot models' are more accurate, the implications for future warming are dire.

IMMINENT GLOBAL CATASTROPHE IF ECS IS HIGH

A higher ECS, potentially above 5 degrees Celsius, drastically shortens the timeline for severe climate impacts. Regions near the equator, densely populated areas like central Africa, India, and South America, face rapid uninhabitability due to extreme heat and crop failure. This will trigger mass migrations northward, leading to immense geopolitical tensions, conflict, and potentially new pandemics. The developed world will struggle to adapt, facing economic collapse, hyperinflation, and a significant decline in living standards, effectively marking a period of regression.

THE IMPERATIVE FOR POLICY CHANGE AND ACTION

The core problem is not a lack of technological solutions, but a failure to implement existing ones. Urgent policy changes are needed, including putting a price on carbon emissions, expanding renewable energy, building nuclear power plants, and investing in carbon removal technologies. The author criticizes ineffective forms of protest like gluing oneself to objects, emphasizing the need for concrete policy action. While acknowledging the difficulty, the message stresses that proactive measures are essential to avert the most catastrophic outcomes suggested by a high climate sensitivity.

COMMUNITY ACTION AND CONSERVATION THROUGH PLANET WILD

Amidst the grim projections, the video highlights Planet Wild as a positive initiative focused on tangible environmental protection. This organization funds ecosystem restoration and wildlife preservation, offering a community-based approach to make a real impact. Through monthly video reports documenting their projects, supporters can see the direct results of their contributions, fostering transparency and engagement. Initiatives like restoring forests or protecting sea turtles demonstrate a hands-on method for combating climate change and preserving biodiversity.

Mentioned in This Episode

●Organizations

●Books

●Studies Cited

●Concepts

●People Referenced

Recommendations for Addressing Climate Change

Practical takeaways from this episode

Do This

Put a price on carbon dioxide emissions now.

Continue to expand renewables.

Build nuclear power plants.

Stop 'bitching' about carbon removal; accept it's necessary.

Consider supporting organizations like Planet Wild.

Donate to community-based environmental protection efforts.

Avoid This

Don't dismiss the severity of climate change based on past experience.

Don't disregard scientific findings on climate sensitivity.

Don't rely solely on technological solutions like AI.

Stop 'gluing yourself to things' as a form of protest.

Equilibrium Climate Sensitivity (ECS) Ranges Mentioned

Data extracted from this episode

Source/Period	ECS Range (°C)	Compatibility with Data
Sophisticated Climate Models (pre-2019)	2-4.5	Assumed baseline
'Hot' Models (2019 assessment)	>5	Initially dismissed due to incompatibility with historical data
Paleoclimate Data Compilation (2020 study)	2.6-3.9	Compatible with lower ECS
Hanson et al. Paper (new re-analysis)	4.8 ± 1.2	Agrees with 'hot' models, challenges previous dismissals

Common Questions

Climate sensitivity, specifically Equilibrium Climate Sensitivity (ECS), measures the temperature change resulting from a doubling of atmospheric carbon dioxide. It's crucial because it dictates how quickly the planet will warm and helps inform climate policy and action plans.

Topics

Health & Longevity Science & Mathematics Society & Philosophy Global Warming Societal Collapse Environmental Policy Climate Modeling Extreme Weather Scientific Consensus Climate Activism

Mentioned in this video

conceptLa Niña

A naturally occurring climate pattern that influences global temperatures, characterized by cooler-than-average sea surface temperatures in the central and eastern tropical Pacific Ocean.

studyCMIP

An abbreviation for the Coupled Model Intercomparison Project, a collaborative scientific effort to analyze data from climate models.

organizationPlanet Wild

A community-based environmental protection organization that funds ecosystem restoration and wildlife preservation projects.

organizationIPCC

The Intergovernmental Panel on Climate Change, which provides policymakers with regular scientific assessments on climate change, its implications and potential future risks, as well as options for adaptation and mitigation.

conceptEl Niño

A climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean, typically leading to warmer global temperatures.

studyNature

A prominent international weekly journal of science, in which Tim Palmer published a comment drawing attention to a study on climate models.

studyCoupled Model Intercomparison Project

A project that collects outputs from various climate models to study climate change. IPCC reports are based on this project's models.

conceptPaleoclimate Data

Indirect climate data from past geological periods, derived from sources like rocks, ice, and fossils, used to reconstruct historical climate conditions.

organizationUK Met Office

The national meteorological service for the United Kingdom, which developed one of the 'hot' climate models that can also be used as a weather model.

personTim Palmer

A scientist and colleague of the speaker who wrote a comment in Nature highlighting a study on climate models and urging further investigation.