This month so far has been full of interesting and often worrisome news about climate change. Here’s a quick rundown of some new discoveries and other confirmations that are already helping us better understand the situation and respond to it.
The tropics swell
It’s long been theorized that one effect of global warming might be that the atmospheric and ocean currents that define the tropics might extend their reach, pushing pole-ward into territory normally regulated by other patterns of air and water movement. With places in the historical tropics seeing record strength storms, it certainly seems like there’s more energy within that part of the climate system. Expansion could be an outlet for that.
(The Hadley, Ferrel, and polar cells often used to define tropical, temperate, and polar regions, from here.)
Atmospheric scientist Qiang Fu’s now published past decade of work might have confirmed that at least part of that is indeed happening. Some of the most rapidly changing temperatures in the lower atmosphere are happening just outside of the tropical Hadley cells. Previously affected primarily by air and water currents in the temperate parts of the planet, those seem to now be blasted by dry air expelled from the tropics especially in their summer seasons.
Their local climates are one of the stress points where the underlying changes that have already begun are showing more obviously, and for them, the changes are almost all negative – they’ll be hotter, drier, and less predictable. The flurry of droughts in places like California, Australia, Syria, and other already fairly dry places on the edge of the temperate zone indicate where things are headed. Especially in the last of those three, the political and economic ramifications of this are very apparent.
Things get hazy
A strangely parallel story seems to be happening at the other major meeting point in the climate system – between the temperate and polar zones. In the northern hemisphere, recent years have been marked by a frequently and strongly negative Arctic Oscillation, meaning that the coldest temperatures aren’t as neatly cordoned off by winds near the pole itself as they typically are.
(Negative Oscillation on the left and Positive Oscillation on the right, from here.)
While that does allow for unusually cold air to sink into temperate areas, leading to phenomena like the “polar vortex” in early 2014, it’s not the same as the tropical zones’ expansion into temperate areas. It’s more of an indirect and inconsistent byproduct of the arctic polar cell becoming less stable and coherent, rather than beefed up and encroaching southward. Warmer air from the temperate zone invades it more thoroughly than colder air from the polar zone surges south. Global warming appears to have supercharged these periodic fluxes, bringing warmer air more consistently to the far north.
Although the mechanics of how that happens aren’t fully understood, what is clear is that a surge of unseasonably warm air into the high arctic in the middle of winter is leading to surreal paucity of sea ice. An area of ice more than half the size of Alaska is simply missing, mostly replaced by the darker open water. That’s a new challenge for the ecosystems in that part of the world as well as a worrying suggestion of what more of the world as a whole might like look soon. Worse yet, unlike the lighter ice, the water easily absorbs the sun’s heat, furthering local and global warming.
At the other end of the world, the antarctic climate is similarly unstable. The Guardian’s recent report on the long term problems posed by a dramatic sea level rise succinctly described the looming threats to the southern pole:
“We can’t keep building seawalls that are 25m high,” said [Oregon State University Professor Peter] Clark. “Entire populations of cities will eventually have to move.”
By far the greatest contributor to the sea level rise – about 80% – would be the melting of the Antarctic ice sheet. Another new study in Nature Climate Change published on Monday reveals that some large Antarctic ice sheets are dangerously close to losing the sea ice shelves that hold back their flow into the ocean.
Huge floating sea ice shelves around Antarctica provide buttresses for the glaciers and ice sheets on the continent. But when they are lost to melting, as happened the with Larsen B shelf in 2002, the speed of flow into the ocean can increase eightfold.
Johannes Fürst, at the University of Erlangen-Nürnberg in Germany and colleagues, calculated that just 5% of the ice shelf in the Bellingshausen Sea and 7% in the Amundsen Sea can be lost before their buttressing effect vanishes. “This is worrying because it is in these regions that we have observed the highest rates of ice-shelf thinning over the past two decades,” he said.
The antarctic is reaching a key tipping point after which it might start to look drastically different from today, with implications that will be felt around the world.
The good news
Against this backdrop of on-going disasters and horrifying possibilities, a commonly pointed out silver lining is that the transition away from fossil fuels and other aspects of our economic system that drive climate change can have positive economic impacts. A look at one of the regions in the UK furthest along transitioning to clean energy sources suggests that isn’t a far fetched expectation at all.
Grimsby, located on the southeastern coast of England, has historically had exactly the type of economy long criticized for being shortsighted. From fishing to heavy manufacturing, its historical economy was unsustainably built on a model of endless extraction and processing. The main exception to that was the military presence, a source of economic stimulus with its own problems and pitfalls. Given that, Grimsby was until recently a “blackspot” of unemployment, and widely considered economically depressed and unstable.
Interestingly, local action to implement more green technology has largely come about with the private adoption of solar and other clean power sources. That said, that transition seems to have been inspired by national action. The economic interconnections between those still living and working in the area and the United Kingdom’s offshore wind energy helped spur independent projects to create lower impact power sources. A small step towards a greener economy can ripple outwards unexpectedly, but still positively.
As daunting as the tasks ahead are, the study of them is helping us better predict what to anticipate and the study of our own economies is assuaging any fears that we can’t easily address them.