U.S. east coast cities would benefit most from reduced emissions

One the of the biggest threats of climate change is the rise in sea level due to melting ice sheets and climate variations in the Earth’s oceans. Sea level rise will impact coastal cities and important ecosystems, and the economic and environmental toll would be catastrophic.

Now, a new study has measured the impact that reducing greenhouse gas emissions would have on specific coastal cities around the world.

Researchers are adamantly working to pose solutions and model scenarios in order to project likely sea level rise outcomes so islands, cities, and nations can be better prepared.

“Mitigating greenhouse gases will reduce sea level rise later this century, with some regions seeing especially significant benefits,” said Aixue Hu, the lead author of the study. “As city officials prepare for sea level rise, they can factor in the compounding effect of local conditions, which are due to the winds and currents that cause internal variability in the oceans.”

Researchers from the National Center for Atmospheric Research created a powerful computer model that estimated the impact two different emissions scenarios would have on winds, currents, and sea level rise.

The results, published in the journal Nature Communications, highlight the need for a speedy reduction of carbon emissions and greenhouse gasses as sea level rise would be significantly less rather than waiting to curb emissions later on.

The research found that cities on the coast of the Atlantic and Indian oceans would benefit the most from emission reduction policies.

The model does not factor in the impact of runoff from melting ice sheets on sea-level rise, so the study does not show a complete picture. The researchers instead focused on climate and the changes in currents and wind patterns that would cause sea level rise.

The team used two sets of computer simulations based on either a business-as-usual emissions scenario or a reduced emissions scenario.

Even if emissions were reduced, it would not mitigate sea level rise for the next two decades. However, from 2061 to 2080 the benefits of reducing emissions would be felt around the world.

In the reduced emissions scenario, the model predicted a reduced sea level rise of 25 percent, lowering the projected rise of seven inches in a business-as-usual scenario to 5.2 inches.

Some of the biggest factors influencing projected sea level rise in the study are winds and currents.

Climate change would cause certain currents like the Gulf Stream to weaken, which would increase sea level rise in the North Atlantic. However, currents in much of the Pacific Ocean seem much less sensitive to climate changes.

This is why some cities like New York City, Boston, and London would see greater benefits if emissions were reduced immediately.  

Even though this new research excluded the impact of melting ice sheet runoff on sea level rise, the results show how sea level rise is affected by climate change and the increased risk that certain coastal cities face unless emissions are reduced.

Sea level rise for major cities worldwide will vary depending on whether society continues to increase emissions of greenhouse gases at the current rate (a scenario known as RCP 8.5) or begins to reduce them (RCP 4.5). Some cities like New York and London will see significant benefits if emissions are reduced.
Image Credit: Simmi Sinha, UCAR

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By Kay Vandette, Earth.com Staff Writer