A three-dimensional map of San Francisco Bay, Calif., with colours representing the projected speed of habitat shift due to climate change. The speeds are slower (blue) at higher elevations. ((Scott R. Loarie))

Climate change will cause the world's ecosystems to move at an average speed of 0.42 kilometres per year to keep up with temperature changes, American researchers say.

The research team behind the calculation says their result shows the importance of reducing greenhouse gas emissions, but also give scientists working in conservation valuable data for planning a response to global climate change.

Scientists at the California Academy of Sciences, the Carnegie Institution of Science, Climate Central, and the University of California, Berkeley, used projections of greenhouse gas emissions over the next century provided by the Intergovernmental Panel on Climate Change to calculate the speed of ecosystem shifting.

The research, published this week in the journal Nature, found that the projected speed of habitat shifting varies from one ecosystem to another.

At the low end are mountain ecosystems such as coniferous forests and high-altitude grasslands, which the researchers say will shift at about 0.1 kilometres per year.

In flatter areas, such as deserts, mangroves and flooded grasslands, the shift will be much faster, possibly more than a kilometre per year, they say.

"Expressed as velocities, climate-change projections connect directly to survival prospects for plants and animals. These are the conditions that will set the stage, whether species move or cope in place," says study co-author Chris Field of the Carnegie Institution.

The scientists said that nearly a third of the habitats they study are shifting faster than their estimates of plant migration speeds, suggesting plants will be left behind when the climate changes.

However, individual species of plants and animals that can tolerate changes in temperature and climate may not have to migrate.

Legally protected areas such as parks and nature reserves may be especially vulnerable to habitat shift.

"One of the most powerful aspects of this data is that it allows us to evaluate how our current protected area network will perform as we attempt to conserve biodiversity in the face of global climate change," said Healy Hamilton of the California Academy of Sciences.

The researchers estimate that only eight per cent of protected areas around the world will maintain their current climate conditions 100 years from now.