Global average temperatures are rising as carbon-based industrial civilization expands, because carbon-based compounds trap thermal energy (heat) the same way glass does in a greenhouse. The 4th National Climate Assessment makes clear: human activity is heating up the atmosphere and oceans, destabilizing the climate system, and putting life, wealth, and opportunity at risk.

The report was produced by the US Global Change Research Program, a cross-cutting science initiative housed in the Executive Office of the President, drawing on work done by 13 cabinet-level agencies, including the Department of Defense. It was established under the administration of President George H.W. Bush, and is required by Congress to produce the National Climate Assessment.

A summary overview of the report’s findings makes clear that risk and vulnerability are accelerating, putting human life, institutions, and the wider economy at risk.

  1. Communities are seeing new levels of vulnerability and threats to quality of life and economic prosperity.
  2. The economy will suffer, as rising costs of too-late adaptation and disaster management combine with degradation of infrastructure and property values.
  3. Interconnected impacts will undermine reliable efficiencies inherent in connections between natural, built and social systems.
  4. Risk reduction is an emerging imperative for decision-makers at all levels.
  5. Water supplies will be severely stressed by intensifying climate disruption.
  6. Health impacts are also spreading and worsening. Vector-borne diseases have expanded their range, and scarcity of healthy food and clean water will worsen overall health impacts.
  7. Indigenous peoples are more immediately at risk, because they are generally more vulnerable and also closer to the natural systems that are being disrupted.
  8. Ecosystems and the natural (unpaid) services they provide are heavily impacted by worsening climate disruption. We do not yet know how to fully measure the economic and institutional impact, in part because we do not know how to live without these natural benefits.
  9. Agriculture depends on reliable trends, natural system services, and fresh water. Climate impacts are degrading soil quality, making water more scarce, and threatening to put needed nutrition out of reach of record numbers of people.
  10. Infrastructure is both highly vulnerable to climate change and also a cost-effective way to invest for climate resilience. Climate-smart planning, engineering and investment must be a priority to avoid dangerous degradation to national infrastructure.
  11. The ocean is interwoven with the climate system around the world. Coastal communities are vulnerable to major storm surges and sea level rise, ecosystems are being degraded at alarming rates, and whole sectors of the human economy are at risk of disappearing in the face of unprecedented numbers of extreme events.
  12. Tourism and recreation depend heavily on natural services and climate stability that will be lost as warming worsens.

Four major takeaways from the report are:

  1. As greenhouse gas emissions increase, warming is accelerating.
  2. As warming accelerates, impacts are compounding, and accelerating.
  3. Inaction with respect to climate disruption will put future prosperity at risk.
  4. We must immediately begin investing for climate resilience and reduce risk.

In many places, climate-related action to reduce risk, build resilience, and transition to zero-emissions energy production and transport is already underway. Analysis shows such actions are not only a good idea in the long-run, and necessary to avoid pervasive catastrophic losses, but that climate action also helps to build stronger local economies and support stronger returns on investment.

While the NCA4 does not make specific policy recommendations, it is clear we need to:

  1. expand good-faith policy engagement at all levels,
  2. price carbon emissions to send clear signals throughout our market economy,
  3. accelerate adaptation innovation—in metrics, mitigation, stewardship, and resilience—and…
  4. move to 100% climate-smart finance as soon as possible.

The clock is ticking, and Nature never sleeps.