Where will climate change hit hardest? Global index reveals vulnerability

Over the next few decades, climate change will test communities in ways that go well beyond storms or heat waves. The pressure point is socioeconomic vulnerability, the conditions that determine whether people can prepare, respond, and recover.

A new global projections database looks ahead from 2020 to 2100 and tracks how social factors may raise or lower that vulnerability.

The database translates hard to compare realities into a single scale, then follows three different development paths to show what changes.

Why climate vulnerability matters

The study was led by Dr. Janine Huisman, a researcher at Radboud University’s Global Data Lab. Her team worked with Climate Analytics to build a forward looking tool that focuses on people, not just physics.

In climate science, risk arises from the interaction of hazards, exposure, and vulnerability. Hazards are the physical events, exposure is what lies in their path, and vulnerability is the human system’s sensitivity and capacity to adapt.

This framing matters because cutting risk is not only about predicting the next flood. It is also about strengthening the social systems that keep losses from spiraling.

How the index works

The team published a peer-reviewed paper that turns 11 indicators into a single index and then projects it to 2100. The index includes seven domains: the economy, education, health, gender, infrastructure, governance, and demographics.

Gender inequality is measured with the UNDP’s GDI. Governance uses the World Bank’s Worldwide Governance Indicators, while education relies on mean years of schooling.

“The GVI quantifies how societies are likely to respond to climate hazards,” said Dr. Huisman. The index emphasizes social conditions that shape readiness and recovery.

Countries with higher education and stronger health tend to anticipate change and adjust faster. Better infrastructure improves evacuation, communication, and emergency response.

Future climate vulnerability paths

Shared Socioeconomic Pathways (SSPs) are stories that scientists use to think about different possible futures for the world. Each pathway describes how people, governments, and economies might change over the next century. 

They include ideas about things like how fast populations grow, how much technology improves, and whether countries work together or stay divided. By comparing these different futures, researchers can see how social and economic choices affect our ability to handle climate change.

Same climate hazard, different outcomes

The projections follow the IIASA SSP database, using three paths that researchers often pair with climate models. SSP1 (“Sustainability”) is a green road with gains in health and education and lower inequality.

SSP2 (“Middle of the Road”) continues mixed trends and uneven development. SSP3 (“Regional Rivalry”) is a rocky road with fragmentation, weaker cooperation, and high challenges for mitigation and adaptation.

Each path reshapes vulnerability not by changing the weather, but by changing social capacity. That is why the same hazard can produce very different outcomes across scenarios.

What the projections show

Under SSP1, the median vulnerability falls steadily this century, with the largest improvements in today’s most vulnerable countries. Under SSP3, change is slow, and large gaps persist between regions with high and low capacity.

Regional patterns remain visible in the mid-century maps. Northern America, Northern and Western Europe, and Australia and New Zealand sit at the low end of vulnerability by 2050 and 2100, while parts of Africa, Southern Asia, and Pacific Island States remain higher.

The gap is smallest in SSP1, wider in SSP2, and widest in SSP3. That spread reflects the storylines behind each pathway.

The projections also show that countries starting in the highest vulnerability group can, under SSP1, approach today’s low vulnerability levels by century’s end. Starting points still matter, but the social trajectory matters more.

Directing resources where they’re needed

The Vulnerable Twenty (V20) countries are home to over one-fifth of the world’s population but produce only about 5 percent of global emissions.

The researchers called for projections that prioritize human capacity, since funding and policy decisions often hinge on those measures.

“This allows policymakers and scholars to assess whether countries remain vulnerable under traditional energy use patterns, or whether vulnerabilities persist even in a rapid transition to renewable energy,” explained Dr. Rosanne Martyr of Climate Analytics.

The scenarios make it possible to test policy ideas against different social futures. The result is a tool that can support international finance decisions, loss and damage debates, and national planning.

The database provides a clearer rationale for directing resources to places where social drivers keep risk high.

Global index with a stable formula

The projections dataset is openly available and arrives in multiple formats. Researchers and agencies can compute country scores every five years and compare them with hazard and exposure layers.

Because the index uses a stable formula, values are comparable across regions and time. That consistency helps avoid moving goalposts when tracking progress.

The tool can be paired with drought, flood, or heat wave maps to estimate risk where people live and work. It also helps identify social levers that can shift outcomes before hazards strike.

Limits of climate vulnerability index

The projections focus on human systems, not on changing hazard patterns. They are designed to complement, not replace, physical climate impact drivers.

Some indicators, like safely-managed drinking water, are not projected, and the authors tested the sensitivity of the index to such gaps. They report very strong correlations between reduced and full indicator sets, suggesting the composite remains stable.

Telephone access and electricity were modeled to saturate at different times across scenarios. That choice reflects real-world adoption curves, with uncertainty acknowledged in robustness checks.

The index is at national scale for now. Within-country differences can be large, and the team notes that a subnational extension is a priority.

What happens next

The authors plan to extend the index to states and provinces so that planners can target investments where they matter most. That finer lens should make adaptation more practical and less blunt.

The database will live on the Global Data Lab site, with updates and visualizations to support wider use. As methods improve, future versions can incorporate better projections for difficult indicators.

The study is published in the journal Scientific Data.

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