I’m referring to our weather.
There’s a basic difference between weather (the stuff that goes on from day to day) and climate (defined as averages taken over at least a 3-decade period). Admittedly, what we’ve been experiencing recently by way of floods might just be weather.
On the other hand, the fingerprints of climate change appear to be all over this year’s weather (if you’ll forgive the mixing of metaphors).
It gets wet in the wintertime. This is not news. Being an island sat in the path of prevailing maritime winds, the UK can achieve ‘wet’ all year round but generally we do get more in the winter than the summer. We had floods in 2012-13 that were pretty devastating. We had floods in 2013-14 that were even worse. Now we’ve had record flooding across a massive sweep of the country starting in 2015 and more still forecast for the next few days at least.
In case anyone missed it, there was a hurricane in the Atlantic in January 2016. They aren’t supposed to show up until June. There was also an iceberg spotted off Newfoundland, where it shouldn’t have been until April. Greenland suffered a mysterious melt-water event just after Storm Frank dumped a load of hot air over that area of the world, at the beginning of the month. Hurricane Alex dumped more hot air into the Arctic last week. Arctic sea-ice, which should be growing rapidly in the depths of the Arctic winter, is at very low levels and practically stalled for a bit in early January (look at the graph of sea-ice extent on the link and you can see the growth of ice flat-lined for several days).
I’m not just listing random events, by the way. All will become clear.
All of this brings me to Storm Jonas. Like Storm Frank, Jonas started life by walloping the US East Coast and is now moving offshore, through very much warmer than usual North Atlantic waters, heading for a meeting with a pool of colder than usual water in mid-Atlantic. When Frank encountered the cool pool, the effect was to supercharge the storm with increased winds and moisture, and Frank then blew right into Britain. Jonas is forecast to do exactly the same, and should (if the forecasts are correct) be landing on our heads from about Tuesday onwards, before swinging up the coast of Norway and delivering, yet again, a dollop of hot air from lower latitudes into the Arctic.
There’s two different points here.
The first one is, should the UK be expecting storms to come off the US continent, spin up again in mid-Atlantic and smack heavily into the UK as a regular thing from now on? We’re on the side of a hill, well above local water courses, but we now know which of our sheds goes below the water table level first and if it rains non-stop for eight days, as it did during/after Frank in this area, we’re going to need a sump-pump in that shed. I’m still in the process of fitting a raised floor to Jet’s cage, because he did not take kindly to 2 inches of water underfoot! The freezers are up on bricks as a temporary measure to keep them running safely. (Bailing out a shed, on and off, for two days is not an activity that I enjoy very much.) Should we be planning for average precipitation to go up from here on in?
Of course, the point about storms gaining force in mid-Atlantic before they hit us brings us to the cool pool. This is an area of the North Atlantic that’s been anomalously colder than average (one of the very few places in the world that still is!) for a couple of years now. It seems to be cooler because it’s fresher water than the normal run of Atlantic seawater, and it’s fresh, cold water because it’s melting off Greenland. Fresh water is less dense than salt water, so Greenland’s run-off is sitting on top of the warmer Atlantic salt water like a lid.
This brings us to the second point about these storms. Since the 1940s, when the Arctic temperatures started being recorded regularly, the temperature in the Arctic has risen to or above freezing 3 times, all in December. Storm Frank made it four times, just barely getting under the bar at the very end of 2015. Jonas might do it again this coming week, which would be a first for the records. (Hurricane Alex, incidentally, pumped air across Western Greenland that was 16-22 degrees C above average – but didn’t quite get the temperatures above freezing).
The more hot air goes into the Arctic, the faster the ice melts. The faster the ice melts, the more fresh, cold water goes into the North Atlantic cool pool. The bigger the cool pool, the bigger the storms, and the bigger the storms, the more hot air goes into the Arctic? (Note that question mark – it’s not proven yet, but I’m starting to wonder!)
As a side note, the bigger the cool pool the more it stalls the Gulf Stream going up into northern waters, so there’s a sort of backlog of hot water sat alongside the US east coast as a result, both raising sea levels and providing lots of energy and water vapour for coastal storms like Jonas.
This is beginning to look suspiciously like a positive feedback loop or, as my mother prefers to call it, a vicious circle.
If it is a positive feedback loop, then each time anything increases in that loop, everything else increases too, which means we can expect more ice melt to lead to more cool pool, leading to bigger storms, leading to more warm air going north, leading to more ice melt….. etc.
It’s always been said by climatologists that the Arctic will see most climate change, faster than the rest of the planet. Feedback loops (all, alas, positive ones) will kick in there before anywhere else. There’s another feedback loop that might tie in with the cool-pool/bigger storms/more ice melt loop, and that’s the simple fact that dark water reflects only 10% of the light (and heat) that falls on it, whereas white snow/ice reflects 90%. Replace Arctic ice and snow with water and the energy absorbed in the Arctic rises, which causes temperature rise, which causes more melting….. you get the picture.
Last week, NASA and NOAA joined the various other meteorological/climate science organisations in unveiling their analysis of 2015 global temperatures and, if you line up the 16 hottest years on record, 15 of them come since 2000 (and the other was 1998, which was freakishly hot due to a very big El Nino that year). Greenland ice melt has been accelerating and Antarctic melt looks like it will be, too.
Time to get that sump-pump fitted in the shed.