By John Keefe and Rachel Ramirez, CNN
The planet is heating up rapidly, resulting in historic drought, deadly floods and unusual melting events in the Arctic. It also causes a constant rise in sea level, which scientists say will continue for decades.
A new study from Climate Central, a nonprofit research group, shows that around 50 major coastal cities will need to implement ‘unprecedented’ adaptation measures to prevent rising sea levels from swallowing their deepest areas. populated.
The analysis, in collaboration with researchers at Princeton University and the Potsdam Institute for Climate Impact Research in Germany, resulted in stark visual contrasts between the world as we know it today. hui and our underwater future, if the planet warms to 3 degrees above the pre-industrial era. levels.
Climatologists reported in August the world is already about 1.2 degrees warmer than pre-industrial levels. Temperatures are expected to stay below 1.5 degrees, they say – a critical threshold for avoiding the most severe impacts of the climate crisis.
But even in the most optimistic scenario, where global greenhouse gas emissions start to decline today and are reduced to net zero by 2050, global temperature will still peak above the 1.5 threshold. degree 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 before reaching maximum levels. .
“Today’s choices will chart our course,” said Benjamin Strauss, chief scientist at Climate Central and lead author of the report.
Climate Central researchers used global elevation and population data to analyze the 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 are at risk of “almost total loss” of their land, according to the report, and eight of the 10 areas most prone to sea-level rise are in Asia, with an estimated 600 million people exposed to flooding in a 3 degree warming scenario. .
According to Climate Central analysis, China, India, Vietnam and Indonesia are among the five countries most vulnerable to long-term sea level rise. The researchers note that these are also countries that have added additional coal combustion 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 are expected to remain in the ground by 2050 to have a greater chance of limit global warming at 1.5 degrees Celsius above pre-industrial levels. Most parts of the world, he said, need to peak in fossil fuel production now or in the next decade to avoid the critical climate threshold.
At the United Nations General Assembly in September, China made a major climate commitment as one of the biggest emitters of greenhouse gases in the world: the country will no longer build new coal-fired power projects abroad, marking a change in policy around its sprawl Belt and Road infrastructure initiative, which had already started to scale back its coal initiatives.
If the planet reaches 3 degrees, Climate Central reports that about 43 million people in China will live on land that is expected to be below high tide levels by 2100, with 200 million people living in areas at risk of water damage. longer term sea level rise.
With every fraction of a degree of warming, the consequences of climate change worsen. Even limiting warming to 1.5 degrees, scientists say the types of extreme weather the world has experienced this summer will become more severe and more frequent.
Beyond 1.5 degrees, the climate system could start to appear unrecognizable.
According to the Climate Central report, around 385 million people currently live on land that will eventually be inundated by high tide, even though greenhouse gas emissions are reduced.
If warming is limited to 1.5 degrees, sea level rise would affect the land inhabited by 510 million people today.
If the planet reaches 3 degrees, the high tide line could encroach over land where more than 800 million people live, according to the study.
The authors note in the report that a key caveat in their assessment is the lack of global data on existing coastal defenses such as dykes and sea walls to fully project exposure to rising seas. Nonetheless, they recognize that due to the impacts seen today with recent flooding and storm surges, cities are likely to reorganize infrastructure to avoid worsening impacts.
“Higher levels of warming will require unprecedented defenses or abandonment in dozens of the world’s major coastal cities,” the authors wrote, “while the tally could be limited to a relative handful thanks to strict compliance. of the Paris Agreement, in particular by limiting warming to 1.5 degrees. “
But coastal infrastructure costs money. Rich countries like the US and UK could afford these measures, but low-income countries could be left behind.
And while many small island nations are surrounded by mangroves and coral reefs that could protect their lands from rising seas, warming temperatures are causing ocean acidification and other forms of environmental destruction that threaten to such defensive measures.
During the first two weeks of November, world leaders will meet in UN Negotiated Climate Talks in Glasgow, Scotland. They will further discuss limiting greenhouse gas emissions, as well as the amount of funding developed countries will commit to helping countries in the South move away from fossil fuels and adapt to the impacts of climate change. climate crisis.
Unless bold and swift action is taken, extreme weather events and sea level rise brought on by climate change will increasingly fill Earth’s future. Scientists say the planet is running out of time to avoid these worst-case scenarios.
“World leaders have a fleeting opportunity to help or betray the future of humanity with their actions today on climate change,” Strauss said. “This research and the resulting images illustrate the huge stakes behind the climate talks in Glasgow. “
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