One of the biggest fears about climate change is that it may be triggering events that would dramatically alter Earth as we know it.
Known to scientists as “tipping events,” they could contribute to mass extinction of species, dramatic sea level rise, extensive droughts and the transformation of forests into vast grasslands – among other upheavals our stressed world can ill afford.
Here are the top six climate events scientists worry about today.
1. The Arctic sea ice melts
The melting of the Arctic summer ice is considered to be the single greatest threat, and some scientists think we’ve already passed the tipping point.
As sea ice melts and the Arctic warms, dark ocean water is exposed that absorbs more sunlight, thus reinforcing the warming. The transition to an ice-free Arctic summer can occur rapidly – within decades – and this has geopolitical implications, in addition to a whole ecosystem being disrupted.
2. Greenland becomes ice-free
The warming of the Arctic may also render Greenland largely ice-free. While Greenland’s ice loss will likely reach the point of no return within this century, the full transition will take at least a few hundred years.
The impacts of the Greenland ice melt is expected to raise sea levels by up to 20 feet.
Half of the 10 largest cities in the world, including New York City, and one-third of the world’s 30 largest cities are already threatened by this sea level rise. Today, they are home to nearly 1.8 billion people.
Other vulnerable American cities include Miami, Norfolk and Boston.
3. The West Antarctic ice sheet disintegrates
On the other side of Earth, the West Antarctic ice sheet is also disintegrating. Because the bottom of this glacier is grounded below sea level, it’s vulnerable to rapid break-up, thinning and retreat as warm ocean waters eat away at the ice.
Scientists expect the West Antarctic ice sheet to “tip” this century, and there is evidence that it already began happening in 2014.
However, the entire collapse of the glacier, which would raise sea level by 16 feet, could take a few hundred years.
4. El Niño becomes a more permanent climate fixture
The oceans absorb about 90 percent of the extra heat that is being trapped in the Earth system by greenhouse gases. This could affect the ocean dynamics that control El Niño events.
While there are several theories about what could happen in the future, the most likely consequence of ocean heat uptake is that El Niño, a natural climate phenomenon, could become a more permanent part of our climate system.