It's Worse. Much Worse.

9 Sad Takeaways from James Hansen's Latest Report

Photo by Sebastian Unrau on Unsplash

Summary: "Global Warming Has Accelerated: Are the United Nations and the Public Well-Informed?"

The report, published in Environment: Science and Policy for Sustainable Development, is authored by James E. Hansen and a team of leading climate scientists, including Pushker Kharecha, Makiko Sato, and others.

Unlike many climate studies that focus on long-term projections or incremental trends, this report delivers a stark warning: global warming is now happening faster than expected, and some of the most widely used climate models, including those from the UN’s Intergovernmental Panel on Climate Change (IPCC), underestimate the severity of the crisis.

The authors argue that the pace of warming over the last decade has surpassed previous estimates, largely due to the reduction of cooling aerosols and a greater-than-expected climate sensitivity to greenhouse gases. Their work raises serious concerns about whether policymakers and the public fully grasp the scale and urgency of the situation.

The 9 Sad Takeaways:

1. Global Warming Has Accelerated Dramatically
   Since 2010, global warming has accelerated by more than 50% compared to the 1970-2010 warming rate of 0.18°C per decade. Earth is now warmer than at any point in the last 11,700 years and may even rival temperatures from the Eemian interglacial period 120,000 years ago.
   
   “No combination of known mechanisms for warming has been able to reconcile our theories with what has happened.”
   
   The study asserts that human-caused climate drivers, particularly greenhouse gases and aerosols, fully account for the observed temperature surge, including a critical jump in sea surface temperatures that has effectively pushed the world past the 1.5°C warming threshold - a milestone previously considered avoidable through emissions reductions alone.

2. Earth’s Energy Imbalance Has Grown at an Alarming Rate
   The rate at which Earth is absorbing more heat than it emits has more than doubled in recent years. This is the most fundamental measure of climate change, and it signals that future warming will be even more severe than current models predict.

3. The UN's Climate Models May Be Too Conservative
   The study argues that the Intergovernmental Panel on Climate Change (IPCC) underestimates both aerosol cooling effects and climate sensitivity.
   
   "We show that IPCC’s emphasis on global climate models led to a marriage of aerosol forcing and climate sensitivity, such that the underestimate of aerosol forcing led to an underestimate of climate sensitivity."
   
   The authors claim that the “Faustian bargain” of air pollution control - where reducing aerosols has led to more rapid warming - was worse than expected.

4. Cutting Ship Emissions May Have Worsened Global Warming
   The International Maritime Organization’s 2020 restriction on sulfur emissions may have inadvertently removed a significant cooling effect from the atmosphere. This change caused a sudden and sharp increase in absorbed solar radiation, leading to a 0.5°C rise in global sea surface temperatures in key shipping routes.
   
   “Aerosols providing a cooling benefit are also inherently dangerous air pollution... Thus, as global pollution control has improved, the cooling effect of aerosols is lost: with the change of ship regulations, our first Faustian payment came due.”

5. A 2023 Temperature Spike Shocked Scientists
   The 2023 global temperature leap of 0.4°C was far beyond what climate models predicted. Some scientists suggested that no existing climate models could explain the rapid rise, leading to serious concerns that current methodologies may be underestimating the speed and intensity of climate change.
   
   “Something else important is occurring.”
   
   The study argues that reduced aerosols, a moderate El Niño, and increasing greenhouse gas concentrations combined to create a perfect storm of warming, which could signal the beginning of a far more dangerous phase of climate change.

6. Sea Level Rise is Accelerating Due to Ice Sheet Destabilization
   Antarctic ice melt is happening faster than expected, threatening multi-meter sea level rise over the coming centuries.
   
   "The most threatening tipping point – the Point of No Return – will be passed when it becomes impossible to avoid catastrophic loss of the West Antarctic Ice Sheet."
   
   The study warns that if the West Antarctic Ice Sheet collapses, it could result in irreversible changes that would submerge half of the world’s largest cities and force mass human displacement.

7. Earth's Albedo (Reflectivity) is Declining Rapidly
   Satellite data shows that Earth is absorbing 1.7 W/m² more solar radiation than a decade ago, a change equivalent to increasing CO2 levels from 419 ppm to 557 ppm. This means that the planet is heating at an unprecedented rate, partially due to the loss of reflective aerosols and melting polar ice.

8. The Climate Crisis is Now an Intergenerational Justice Issue
   The delayed response of climate systems means that today’s youth will inherit a far worse crisis than policymakers currently acknowledge.
   
   The authors stress that fossil fuel reductions alone are not enough - active carbon removal strategies (editor note: still to be proven as feasible on a mass scale) will be necessary to prevent further climate destabilization.

9. If This Report is Correct, Climate Policy is Already Outdated
   The findings challenge the UN’s climate assessments, suggesting that policymakers and the public have been misled about the pace of warming, and demand urgent, science-driven solutions. If the conclusions are correct, then many existing climate policies and emissions targets are already outdated, and far more aggressive action is needed to avoid the worst outcomes. (Editor note: Good luck with that - "Just 10 of the 195 parties signed up to the landmark Paris Agreement have published their new emissions-cutting plans, known as “nationally determined contributions” (NDCs), by the 10 February deadline." - Carbonbrief)

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