UKH

It seems that now many flights have stopped the skies have cleared, the days are sunnier and the nights are clearer.  There can be no clearer indication of the amount of damage the aviation industry is doing to the environment.

Is it now time to limit (ration) air travel?
or perhaps, we don’t see environmental issues as a personal problem, and we’ll soon be planning a climbing trip to the Alps and a couple of city breaks once the Corona threat has passed.

In reply to paulh.0776:

I'm not sure you understand correlation...

In reply to paulh.0776:

Not downplaying the environmental concerns, but do you not think the nicer weather could be more to do with the fact that we are moving from winter to summer? Seems more plausible that a week of reduced air travel.

I seem to recall that we had some days of sunshine last year too, and possibly even the year before, despite air travel. I don’t think a few sunny days is a clear indication of anything other than the fact that weather is changeable, sorry. 

In reply to paulh.0776:

I’ve no doubt this is good for the environment.... but the weather is more due to a nice high pressure system.

In reply to Stuart Williams:

That's what I was going to put but mine was shorter...

In reply to Oceanrower:

After Eyjafjallajökull blew, we had some glorious evenings; n=2.... Proof?!?

In reply to Oceanrower:

I saw yours after I posted and thought “yeah, that would have covered it just fine”.

In reply to paulh.0776:

Can you lot stop going on about the sun!? Cloudy here, rained this morning, rained yesterday when we went for our daily exercise. 😭

In reply to aln:

Crystal clear skies and barely a breath of wind here in Mancunia
And really quiet, I was out for a wander earlier, passing near a cherry blossom tree, and could hear this humming noise.  Stopped and had a look up, loads of bees feeding away.  Never really noticed that before.

In reply to aln:

Sorry, if it’s any consolation I’m having to work inside today to avoid adding to yesterday’s sunburn. 

In reply to Stuart Williams:

There's actually a lot of evidence that aviation increases cloud cover through cloud nucleation via aerosol particles and increased sulphur dioxide. This 'global dimming' effect has been noted in separate long term studies from Australia (pan evaporation) and Israel and was picked up in America after 9/11 when all planes were grounded. It's negative feedback effect from pollution that's actually helped to limit the warming effects of increased atmospheric greenhouse gasses. So ,even though high pressure is giving us the dry weather it's likely that the grounding of flights has contributed to the blue skies.

In reply to AJM79:

Interesting, thanks. I’ll do some reading around that. 

Although I remain of the opinion that 3 sunny days is not the irrefutable causal evidence the OP suggests. 

In reply to paulh.0776:

I think this is going to be a disaster for the environment. Far from ending flying etc and wondering if we should eat Pangolins or burn our forests down this is going to precipitate a rush to restart the economy at whatever the cost in carbon, especially as fuel is cheap.  A few weeks ago we felt awful if we used a plastic coffee cup. Now we are churning out disposable PPE and no amount is too much.

I have a nasty feeling that HMS Humanity is going to be so relieved to have survived the torpedoes of Coronavirus that they'll forget that the stopcocks had been left open and that even before all this started there was a bit of a list to port.

In reply to AJM79:

I was Going to post about that research. However we have no vapour trails spoiling those clear blue skies!

In reply to paulh.0776:

Most golf courses in UK and Ireland shut. Most have no maintenance going on. If the Good Lord spares me I'll be curious to see if they revert to their natural state and what effect will it have on wild life. Golf has been declining in popularity in recent years so quite a few golf courses might not re-open when this is all over. Realise this might please a lot of folks on this forum but, despite not having played golf for many years, it would sadden me.

In reply to paulh.0776:

The current weather has nothing to do with the cessation of air travel but obviously air quality will be affected. There's going to be a wealth of data re: pollution , global warming, biodiversity effects from this

In reply to paulh.0776:

I understand the difference between weather and climate, it just seemed a little too much of a coincidence, 

I hope that the science is watching, taking notes and then our politicians will listen as intently to our experts and act as they have done with the c-19 .

ps.  Thanks to Ajm79 for the info re 9/11 

In reply to DerwentDiluted:

> this is going to precipitate a rush to restart the economy at whatever the cost in carbon, especially as fuel is cheap.  A few weeks ago we felt awful if we used a plastic coffee cup. Now we are churning out disposable PPE and no amount is too much.

Sad to say that I agree. 

In reply to DerwentDiluted:

Sigh, sadly you are likely to be right. Lurching from one crisis to the next is our destiny.

And the first one might revolve around that cheap oil not being cheap anymore. It's humanity's crack cocaine.

In reply to Blue Straggler:

As long as all that PPE was burnt efficiently we'd be massively reducing emissions. Bring on much more of it please.

In reply to paulh.0776:

Unfortunately when someone says "too much of a coincidence" I find it generally pays to interpret it as "after seeing a random semblance of a pattern in a huge noisy data set, cognitive biases led me to ignore all disconfirmatory evidence or alternative explanations". That's not meant as any slight on you, just an observation on typical patterns of thought.

Like when it is such a coincidence that someone phones you just as you are thinking about them. It isn't an amazing coincidence, you have just forgotten about the many many times that you think of people who then completely fail to phone you moments later.

Either way, I think you are right that there will be a lot of benefits to the environment from a period of global travel restrictions. But I don't think the UK weather right now tells us anything. You could be right, but weather systems are massively complex and a single weather event in one country is near enough meaningless in terms of drawing any conclusions. Even more so since a lot of weather data comes from planes, which are now grounded, so the data and models at the moment are poorer than usual.

In reply to paulh.0776:

I have noticed in recent days that petrol is getting much cheaper - down to £1.04 a litre in my local garage. We have also had great weather. This cannot be a coincidence. Clearly cheap petrol is good for the environment. Surely the govt should be subsidising it further

In reply to jezb1:

Hi pressure system creates an inversion - which traps pollen soot and other particulates close to ground level, typically 3-4000 ft. So in fact, hi pressure creates hazy conditions, the clearest come after a cold front has swept the inversion and it's murk away.

Under current restrictions there is massively reduced air pollution at all levels, incl particulates in urban zones. So, absence of contrails PLUS reduction of murk under the hi pressure inversion (vehicles) == clearer conditions, correct

ps. I'm in SW France so can't comment on visible evidence 

In reply to AJM79:

I think it’s generally accepted that airplane exhausts will increase the chances of cloud forming through ejecting a load of cloud condensing nuclie – one of the key ingredients for forming cloud – into the atmosphere. At the south pole it’s a known phenomenon that an incoming plane can sometimes create fog from what was clear dry air just a moment ago.

Whether cloud will form on any given day, and how long it will last, will depend on the atmospheric condition, in particular the amount of moisture in the atmosphere at that level. The air is often very dry at airliner cruising altitude, hence why you don’t always get contrails or if you do they often evaporate quickly. Under high pressure systems, the large scale subsidence of air, causing it to warm and dry out, will normally mask any effect of the increased nuclie.

Their contribution to the warming or otherwise of the planet is an interesting one. As you say, by day they will reduce warming effects through reflection of incoming shortwave radiation. But at night they will increase warming by reducing the amount of heat radiated out to space with the cloud cover acting like a blanket. As far as I’m aware there isn’t a clear consensus on which affect is more significant, at least partly to do with the difficulty in distinguishing the effect of aviation induced clouds from other processes.

In reply to LeeWood:

You’re right, high pressure systems can, and often do, create inversion, but not always, and the height of the inversion will vary considerably each time.

It’s also correct that inversions will trap pollutants beneath it, leading to hazy conditions, although this will tend to depend on where the air has originated from, and is typically associated with a high extending from continental Europe, or to a lesser extent a home grown one, where there are plenty of sources of pollutants. If it originates over the north Atlantic or the Arctic, it is going to be largely free of pollutants (although salt particles can help create clouds). Temperature will have an effect too. Under cold conditions the air will be denser and less able to hold pollutants aloft than warm air. Think of those crisp cold high pressure days in winter with crystal clear skies. The really hazy high pressure conditions normally occur in summer when more pollutants are able to be suspended in the warmer air.

The recent nice weather, at least across England, has been due to high pressure over central/eastern Europe. However, as it’s still early in the year it is relatively cold air so hence the lack of hazy conditions, although I agree that the reduced air pollution will have significantly added to this as well.

In reply to paulh.0776:

1027hPa meet the man who thinks nice weather is caused by no planes.

Sorry Paul, I agree we're killing our world and the quiet right now is lovely but this is just a nice spell in spring. Enjoy it if you can.

jk

In reply to MikeR:

Interesting point and one I used to subscribe to. Although I haven't dug up any empirical data on it, I thought it was generally accepted that the albedo effect outweighed the trapping of infra-red rays. After all incoming radiation during daytime is greater than outgoing at night with much of the insolation that enters the atmosphere being scattered anyway (even a large proportion which reaches the ground) whereas on the other hand outgoing radiation at night constitutes only the proportion of energy that has been absorbed and is therefore less.

In reply to Stuart Williams:

Noooooooo!!!!!!!

Still cloudy in Fife ☹

In reply to AJM79:

Yes, I suspect you are right. It certainly seems to fit in theory. I think proving it is much harder due to the difficulty in differentiating the contribution from aviation induced cloud and naturally occurring variations.

In reply to MikeR:

The Australian study showed a fall in evaporation despite a rise in temperature and this was attributed to an increase in cloud cover with evaporation being more reliant on sunlight than temp. It is a well known and widely recognised phenomena and not just my personal pet theory with lots of publicised papers on it. Look up global dimming if you want to find out more

In reply to AJM79:

In my, admittedly limited, understanding of global dimming, isn't that taking into account clouds at all altitudes?

I would have thought that aviation induced cloud is mostly at high altitude, where I believe the cloud has a net warming effect due to being much colder and generally composed of ice rather than water droplets.

In reply to MikeR:

True it's much colder but the sunlight has the same energy at altitude as at sea level (even more in the stratosphere), you only feel the warmth when it is absorbed and reflected as infra-red. By blocking the incoming radiation it greatly increases the Earths albedo effect so while the effects of cloud at altitude may be a localised warming at altitude the loss of radiation reaching the surface where it can be absorbed and heat the Earth contributes to a net cooling effect. 

Most calculations of global dimming take into account all emissions of sulphur dioxide not just from aviation, from memory I think that the burning of sub-standard coal is one of the larger contributions, and they are normally calibrated against earlier figures showing that it is an increasing phenomena in its favour it is currently buffering us against increased atmospheric warming to the extent that the release of sulphur dioxide has been floated as a possible solution to climate change. Certainly if you look at geological records there is evidence of a cooling of the paleoclimate after large scale volcanic activity which releases sulphur dioxide and I believe that the mini ice age was a result of Krakatoa.

In reply to paulh.0776:

correlation isnt causation....be talking about chem trails in a min,,