'Science and realism': Governments plan for doomsday climate scenarios

From sudden ice ages to ferocious superstorms, scientists have long warned of scary doomsday scenarios, and now some governments and experts have made moves to start preparing for the worst.

For example, dozens of climate scientists recently sent a letter to northern European leaders, warning of a major change in an Atlantic Ocean current due to human-caused climate change – one that could trigger abrupt shifts in weather patterns and damage ecosystems worldwide.

It's yet another development in the longstanding concern over the Atlantic Meridional Overturning Circulation (AMOC), which has also served as fodder for the the "Day After Tomorrow" disaster movie (which took many liberties with the scientific consensus).

"I think it is reasonable for the Nordic countries to consider how they might prepare for an AMOC shutdown," said Baylor Fox-Kemper, a professor of Earth, Environmental, and Planetary Sciences at Brown University, in an email to USA TODAY. "Similarly, Florida should consider stronger hurricanes and sea level rise, California should consider bigger wildfires, and India should consider more intense heatwaves."

Governments around the world are confronting and preparing for some dramatic disaster scenarios that could unfold in the next few decades as climate change continues. Here's a few:

What if the AMOC collapses?

Climate change could lead to a collapse of the Atlantic Meridional Overturning Circulation, a system of ocean currents that transports warm water into the North Atlantic and provides Europe its mild climate. Such a collapse could trigger rapid weather and climate changes in the U.S., Europe and elsewhere. If it were to happen, it could bring about an ice age in Europe and sea-level rise in cities such as Boston and New York, as well as more potent storms and hurricanes along the East Coast.

"Such an ocean circulation change would have devastating and irreversible impacts especially for Nordic countries, but also for other parts of the world," the scientists said in an October letter to the Nordic Council of Ministers, which comprises five countries, including Denmark and Sweden, and three autonomous territories.

The letter urges the council to actions that could involve calling for global greenhouse-gas emission cuts.

"Preparation involves science and realism about the scale of the effects, who will be most affected, and what can be done," Fox-Kemper said. "In the case of AMOC, only emissions reductions can reduce the hazard its change presents. These same nations and states can also reduce emissions, although that has proven difficult, partly because those who emit are often distant from those who will be impacted."

United Kingdom confronts climate change

The AMOC isn't the only concerning climate issue that governments are worried about.

In the United Kingdom, the government's new Advanced Research and Invention Agency (similar to the USA's DARPA) is focused on two related climate tipping points, according to MIT Technology Review. "One is the accelerating melting of the Greenland Ice Sheet, which could raise sea levels dramatically. The other is the weakening of the North Atlantic Subpolar Gyre, a huge current rotating counterclockwise south of Greenland that may have played a role in triggering the Little Ice Age around the 14th century."

By developing an early warning system, “we might be able to change the way that we think about climate change and think about our preparedness for it,” said Sarah Bohndiek, a program director for the research program and a professor of biomedical physics at the University of Cambridge.

Fox-Kemper said, "preparing for climate change is something countries have within their control, although it is likely to be costly and only partly effective."

Early warning system in the Pacific

In the Pacific Ocean, in the tiny island nation of Timor-Leste, climate change "poses significant challenges to the country’s development through rising mean temperatures, sea level rise, tropical cyclones, floods and prolonged droughts," according to the United Nations Environment Programme.

A new United Nations early warning system will help to expand and upgrade Timor-Leste’s climate information capabilities and early warning systems.

"Early warning systems are a proven cost-effective disaster risk reduction and climate change adaptation measure which has been demonstrated to save lives, livelihoods and ecosystems in the face of climate-related hazards," the U.N. said.

With climate change, the frequency and intensity of climate-related hazards is expected to increase, the U.N. said. Early warning systems "have a great potential to avert disaster risk and minimize loss and damage caused by climate-related hazards through supporting well-informed science-based decision-making."

"Giving just 24 hours' notice of an impending hazardous event could reduce damage by 30 percent, while investing just $800 million in early warning system in developing countries would prevent losses of $3 to $16 billion annually."

Rain forests under siege

A new early warning system uses satellite data to sound the alarm on growing threats to the world's tropical forests, including worsening drought and logging, and aims to stop them reaching a point of no return. Backed by the National Geographic Society and Swiss watch manufacturer Rolex, almost 60 international scientists devised the system to track rising dangers to the planet's rainforests, which are vital for protecting the climate and nature.

The new tropical forest vulnerability index tracks and analyzes the impact of changes in the climate and the use of land – such as clearing it for farming – on local forests, as well as how they are responding to such stress factors.