Photo illustration of potential sea levels at Lalbagh Fort in Dhaka, Bangladesh due to human-caused global warming. Original image by Syedsazzadulhoque via Climate Central
CNN  — 

The planet is warming rapidly, resulting in historic drought, deadly floods and unusual melting events in the Arctic. It is also causing steady sea level rise, which scientists say will continue for decades.

A new study from Climate Central, a nonprofit research group, shows that roughly 50 major coastal cities will need to implement “unprecedented” adaptation measures to prevent rising seas from swallowing their most populated areas.

The analysis, in collaboration with researchers at Princeton University and the Potsdam Institute for Climate Impact Research in Germany, resulted in striking visual contrasts between the world as we know it today and our underwater future, if the planet warms to 3 degrees Celsius above pre-industrial levels.

What sea-level rise could look like at the Plaza de la Catedral in Havana, Cuba. Original by Gorupdebesanez via Climate Central

Climate scientists reported in August the world is already around 1.2 degrees Celsius warmer than pre-industrial levels. Temperatures should stay below 1.5 degrees, they say — a critical threshold to avoid the most severe impacts of the climate crisis.

But even in the most optimistic scenario, where global greenhouse gas emissions begin to decline today and are slashed to net zero by 2050, global temperature will still peak above the 1.5-degree threshold before falling.

In less-optimistic scenarios, where emissions continue to climb beyond 2050, the planet could reach 3 degrees as early as the 2060s or 2070s, and the oceans will continue to rise for decades beyond that before they reach peak levels.

“Today’s choices will set our path,” said Benjamin Strauss, the chief scientist at Climate Central and lead author on the report.

Simulated climate-change floods at the Chhatrapati Shivaji Maharaj Vastu Sangrahalaya museum in Mumbai, India. Original by Sailko via Climate Central
How sea levels caused by 3°C of warming could affect the Temple of Literature in Hanoi, Vietnam. Original by Nguyễn Thanh Quang via Climate Central

Climate Central researchers used global elevation and population data to analyze parts of the world that will be most vulnerable to sea level rise, which tend to be concentrated in the Asia-Pacific region.

Small island nations at risk of “near-total loss” of land, the report says, and eight of the top 10 areas exposed to sea level rise are in Asia, with approximately 600 million people exposed to inundation under a 3-degree warming scenario.

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    According to Climate Central’s analysis, China, India, Vietnam, and Indonesia are in the top five countries most vulnerable to long-term sea level rise. The researchers note that these are also countries that have added additional coal-burning capacity in recent years.

    In September, a study published in the journal Nature found nearly 60% of the planet’s remaining oil and natural gas and 90% of its coal reserves should remain in the ground by 2050 to have a higher chance of limiting global warming to 1.5 degrees Celsius above pre-industrial levels. Most regions around the world, it said, must reach peak fossil fuel production now or within the next decade to avoid the critical climate threshold.

    At the UN General Assembly in September, China made a major climate pledge as one of the world’s largest emitters of greenhouse gases: the country will no longer build any new coal-fired power projects abroad, marking a shift in policy around its sprawling Belt and Road infrastructure initiative, which had already begun to dwindle its coal initiatives.

    If the planet hits 3 degrees, Climate Central reports that roughly 43 million people in China will live on land projected to be below high-tide levels by 2100, with 200 million people living in areas at risk of sea level rise over the longer term.

    Potential sea levels at Durban City Hall in Durban, South Africa. Original from Google Earth via Climate Central

    With every fraction of a degree of warming, the consequences of climate change worsen. Even limiting warming to 1.5 degrees, scientists say the kinds of extreme weather the world experienced this summer will become more severe and more frequent.

    Beyond 1.5 degrees, the climate system could begin to look unrecognizable.