rand.org - Research reports

Global Catastrophic Risk Assessment
Henry H. Willis, Anu Narayanan, Benjamin Boudreaux, Bianca Espinosa, Edward Geist, Daniel M. Gerstein, Dahlia Anne Goldfeld, Nidhi Kalra, Tom LaTourrette, Emily Lathrop, et al.

Congress passed the Global Catastrophic Risk Management Act in 2022, which requires that the Secretary of Homeland Security and the administrator of the Federal Emergency Management Agency coordinate an assessment of global catastrophic risk related to a set of threats and hazards. The U.S. Department of Homeland Security Science and Technology Directorate and the Federal Emergency Management Agency requested the Homeland Security Operational Analysis Center's support in meeting this requirement. The authors of this report document findings from the resulting analysis.

This is what they're looking at:
This report summarizes what is known about the risks associated with six threats and hazards: artificial intelligence; asteroid and comet impacts; sudden and severe changes to Earth's climate; nuclear war; severe pandemics, whether resulting from naturally occurring events or from synthetic biology; and supervolcanoes.

So. What is the risk level?

Climate
change
Most significant consequence:
• The primary significant
consequences would be death,
disruption, and degradation of
ecosystem stability.
• The secondary significant
consequence would be the
slowing of economic growth
and reduced human capabilities
induced by environmental,
economic, and ecosystem
damage.

Likelihood of risk:

• A 2.0°C rise in temperature is
likely and considered catastrophic
on a local to regional scale but
not globally. The probability of
more-severe global warming over
4.0°C is estimated to be less than
1% but could create potentially
catastrophic outcomes.

Quality of evidence supporting the assessment:
• Observations of ecological
changes and significant
uncertainty about climate hazards
and Earth-system tipping points
exist, with robust near-term
temperature predictions but
greater uncertainty in later
decades.

In other words, it depends on their models.

The TL;DR is that climate change isn't considered a global threat.

The report also has something to say about climate activists:
“A strong, international activist movement now exists that engages in advocacy for addressing climate change. That movement emphasizes the urgency of climate change; sponsors civic engagement efforts, including protest and civil disobedience, particularly among youths around the globe; and argues that climate change is a potential existential risk. . . although social movements reflect a genuine and legitimate concern about climate change’s potential risks to society, they are not necessarily grounded in objective assessment of those risks.”