ANN ARBOR—Without dramatic reductions in greenhouse-gas emissions, most of the planet’s land-based ecosystems—from its forests and grasslands to the deserts and tundra—are at high risk of “major transformation” due to climate change, according to a new study from an international research team.

The researchers used fossil records of global vegetation change that occurred during a period of post-glacial warming to project the magnitude of ecosystem transformations likely in the future under various greenhouse gas emissions scenarios.

They found that under a “business as usual” emissions scenario, in which little is done to rein in heat-trapping greenhouse-gas emissions, vegetation changes across the planet’s wild landscapes will likely be more far-reaching and disruptive than earlier studies suggested.

The changes would threaten global biodiversity and derail vital services that nature provides to humanity, such as water security, carbon storage and recreation, according to study co-author Jonathan Overpeck, dean of the School for Environment and Sustainability at the University of Michigan.