Tuesday, June 28, 2016

Is the World Warming Pt II, 2000 – 2016, and El Nino.

So here’s the chart of HadCRUT data for the years 1980-2016. Our period of interest starts after the spike in the middle of the chart.




There are two distinct phases post 1998. First, a lack of overall increase in temperature between 1998 and 2014 (the infamous “hiatus”). And then a record breaking strong increase in temperature in the last two years.

The previous post finished just after the record year of 1998. There were prophets of climate doom, but also deniers who said the earth wasn’t warming at all. The chart since then shows two things; firstly the hiatus gave a lot of support to deniers, or those who argues for some kind of natural variation. It also left a number of people who made the more alarmist claims looking slightly stupid. The sharp increase in the last two years however demonstrates that warming is clearly happening. Not shown on the charts is the fact that now all measurements including satellite measures are in agreement.

We know as naturalists that there have been significant population movements in the last 20 years. Most inspect species are moving north, or moving higher. There is a long list of insect and bird species that have expanded their range from Europe to the UK, and conversely we see a disappearance of many bird species from the southern parts of their range even where there has been no change in habitat. Spring migration is happening on average 2 weeks earlier than it was thirty years ago. It is hard to avoid the conclusion that if all our measurements show global temperature increasing, and all our flying creatures are behaving as if the earth is warming, then the earth is warming. Anyone who doubts this warming needs to explain not just why all the different methods of measurement all show this, but why the natural world has responded as if the world is warming.

Having established that warming is happening, the next questions – how fast and what happens next – are much harder to call. Scientific theories do two things: allow us to understand the past, and allow us to predict the future (even if only in a conditional if we do this, then that will happen). Climate science is reasonable at explaining the past, but is currently poor at predicting the future. The chart of the temperature anomaly above is a good illustration of this. No-one predicted the hiatus, but efforts are now underway to explain why we have this choppy behaviour in temperature behaviour. The emerging explanation centres round the importance of the oceans in global warming and the role of El Nino.

Firstly some quick calculations.

Heat capacity of the ocean = 1.35 x 10^21 Kg x 3.993 KJ/Kg/C (specific heat capacity of salt water) = 5.4 x 10^21 KJ/C
Heat Capacity of the atmosphere = 5.1 x 10^18Kg x 1 KJ/Kg/C = 5.1 x 10^18 KJ/C

So the sea holds roughly 1000x more heat than the atmosphere (if they are at the same temperature). Hence over a long period the oceans play a key role in global temperatures. The temperature of the atmosphere can not, over a long period, diverge too far from its historic relationship. Thermal energy is transferred between the two. The mechanism that seems to have a significant role in how and when this is done is the global weather phenomenon of El Nino and its twin La Nina.


El Nino and La Nina.

El Niño and La Niña are opposite phases of an oscillatory climate cycle in the Pacific ocean, and have been known about since the 1600s.

No-one really understands the mechanics of el Nino, or can predict when it will happen and how strong it will be [1,2]. Under normal conditions, trade winds blow west from the equator keeping warm surface water off Asia. In El Nino years these winds do not blow as hard and the warm water flows to the American west coast bringing rain with it. La Nina is the opposite; the winds blow strongly restricting the flow of warm water. The consequences are far-reaching around the globe, and one consequence we are beginning to understand is that El Nino releases heat from the ocean into the atmosphere.

To illustrate this I’ve taken a table of El nino/La nina years [3] divided by strength and calculated the average global temperature anomaly in the subsequent year (ie 1998 anomaly for the el Nino in 1997-98). This is shown (poorly – mac Excel is horrible) below

The labels on the right go from -S (Strong La Nina) to <> ("normal") to +VS (Very Strong el Nino)


This shows generally that the stronger El Nino, the higher the temperature anomaly.

Current thinking then is that during the Hiatus years 1998-2013 the world was still absorbing thermal energy, but this was being stored by the oceans. The El Nino of 2015-16 which was a very strong one has released a lot of heat and so seen a significant sharp increase in temperature. My prediction is that in the next few years we may see a hiatus established for a decade or so at this new higher temperature, and then some years down the line the process repeats and the temperature moves up sharply. But that’s just my view.

Next I will look at the opinions around why the world is heating starting with greenhouse gases.




Sunday, June 26, 2016

Is the world warming? Pt I

In this post I will look at measuring global temperature; how it is done and the global record up to the year 2000

To know whether the world is warming you have to have a means of measuring the temperature of the world, and to have a meaningful record that goes back a sufficient period of time to be able to make convincing confusions from the data.

There are a range of useful measurements; sea temperatures, land temperatures, air temperatures, and radiated temperature detected by satellite.

Sea Surface temperature

Measuring ocean temperature would seem to be a straightforward thing to do, but it varies over latitude and depth. Surface temperature is measured by satellite detecting a variety of infra-red and other electromagnetic radiation [1]. This has only been available recently in a consistent form since 1980. Historic measurements were taken from buckets dipped in the sea or from water around engine intakes.

The UK met office has been very active in measuring temperature, and there is a much quoted paper from 2002 which gives 22 pages of analysis, charts and graphs on sea measurement [2].  It states “Our objective is a spatially complete, monthly SST analysis for 1871 to date, preserving real climate signals on global, ocean-basin and subregional scales, while minimiz- ing random errors, sampling noise, and systematic biases.” And has 22 pages of detail on how data has been corrected, etc and then produces graphs from 1880.

The data is presented as the difference (referred to as the anomaly) between the measured temperature and the average of a given period (generally 1961-1990). The conclusion is generally of slow increase up to around 1980 and then a marked increase from 1980 to 2000. The graphs look alarming but the full increase from 1880 to 200 varies from 0 to 2C depending on region. Whether 2C is a significant increase is something I will return to, and given the amount of massaging that has been done I think it is reasonable to have some scepticism about the results.

Land temperature

Land temperature is derived from a large network of ground stations which have technical and positioning specifications. Again this is problematic because over time the world has become more urbanised and urbanisation generally increases temperature. There has been some discussion on how reliable these measurements are, but the results need to be viewed in the light of other measurements [3].

Atmospheric temperature.

The temperature of the atmosphere at height is measured most consistently through satellite sensing [4]. This was the subject of much debate in the late 20th century as results did not support warming seen from land or sea.  Some work has been done in explaining this (“atmospheric drag” for instance) but at the end of the 20th century this reading still lagged causing some to dispute the other readings. It is not clear why, given a dispute, we would choose to believe the atmospheric ones, particularly as these measurements relate to the higher atmosphere and the natural world largely occurs at the surface of the world or in the oceans.

HadCRUT

One of the most widely used data sets for temperature data is the HadCRUT series [5]. This comes from the UK Met Office at Hadley. Their web site has a number of data sets including marine, upper air, and land surface measurement that are combined in the HadCRUT series of data.

HadCRUT Results up to 2000

There was considerable debate around the turn of this century about global warming with some predicting imminent disaster and some denying the world was warming at all. So here is some data from the combined data set HadCRUT 4 [6]



The LH scale is the difference between the measured temperature and the average for 1961-1990.

The total temperature increase recorded here from 1850 is around 1C. By eye the temperature is stable up to 1910, there is a significant increase from 1910 to 1945ish, then flat until 1975, then strong increase to a record year in 1998.

1998 in particular was a watershed year. The rapid increase led to some predicting runaway temperature increases and significant global warming with catastrophic major changes in climate occurring shortly. Others disagreed. Some thought the overall temperature changes were low and the data questionable, and that we weren’t warming at all. Another group argued that the earth’s temperature changes over time anyway, and this was just part of the natural variation in climate. The century ended with disagreement and debate. In the next post I’ll look at how this debate looks nearly 20 years later.

[4] “The Rough Guide to Climate Change” by Robert Henson, Part Three – keeping track.

Tuesday, June 21, 2016

Climate change: Global Warming Posts

Global Warming is a critical subject of our times. The debate has been raging for a few decades now, and there is still considerable disagreement and scepticism. There is a particular relevance  for those interested in the natural world as environmental changes clearly have the capacity to cause havoc, and bird watchers of a particular vintage have seen significant changes of the bird population in our life time. So with some time on my hands I decided to investigate.

I am sceptical by nature. US politicians pronouncing there is no global warming and there is a giant conspiracy are scary sure enough, but I’m not sure I like the incessant hectoring about imminent catastrophe by various groups all of whom seem to have some vested interest in creating scare stories about the climate. In addition there is significant disagreement about basic scientific questions.  So, who to believe? Who to trust?

I have a background in science, but not any particular knowledge of climate science, so much of this is new to me. There are thousands of scientists working on a variety of different aspects of measurement and explanation of climate science, so trying to give an overview that does justice to the sheer quantity and depth of work done is in many ways an impossible task. I have been down a particular avenue of inquiry and ended up with a particular set of conclusions, but that is just my view; someone else could engage in the same exercise, take a different route, and end up with different conclusions.

I’ve split the investigation into four parts:

i)               Is the world warming? (answer – it is)
ii)             Is the warming caused by man’s activities?
iii)            Is something very bad about to happen?
iv)            What are the effects (current and future) on wildlife?


I’m still researching and writing the posts so they will appear sporadically amongst the general rubbish. I’ll tag the posts so you can pull them all out in one go.

Wednesday, June 15, 2016

Grumpy man birding

In grumpy mode today. Titchwell or the Brecks? Titchwell has had a good run but surely there's nothing there in the middle of June, and the Brecks are bursting with really easy ticks, so the Brecks it is. First up King's Wood. The place with the highest concentration of Woodlarks in East Anglia. Well not when I'm there. Then as I'm leaving an old chap engages me in conversation, and yes its a pleasure to talk to him, but there are ticks to be had.

On to Mickle Mere for the Glossy Ibis. After getting lost down myriad tiny roads I find it, and its a gem of a reserve, a shallow mere in Breckland with lots of waterfowl - Shoveler, Shelduck, Teal, Redshank, Oystercatcher, Little Egret. Just one bird missing. A local pops up to tell us what a marvellous reserve it is, smashing views of Cuckoos etc and the Glossy Ibis will be along soon, which it isn't. We are swapping tails and anecdotes and I am just about to deliver the side-splitting punch-line when the local says - "its just there behind you" and I think well that's a bit rude interrupting my tale, and that isn't the punchline anyway, when I realise he is referring to the Ibis, and as I turn round I get a nano-second of black something going into a willow. He is sure that was it, and I am confident of two things; he is right, and it isn't coming out of there any time soon.

So desperation mounting and on to Weeting Heath. Surely, surely, this time a year tick. The Stone Curlew chicks have apparently just been eaten by a fox, but there is a walk through the woods opposite with lots of great heathland birds including the recently bereaved Stone Curlews. Head down and off I go, meeting a couple of genial old birders who inform me I have walked past the birds. I retrace my steps, set up scope, and there are a couple of Stone Curlew, some way apart, sitting morosely looking for all the world like two birds who have flown a couple of thousand miles for the sole purpose of breeding and just watched their children being eaten. If I have ever seen two more miserable looking birds then I cannot remember it. Onwards to the top of the forest and a watchpoint "Tree Pipit, woodlark, can't miss 'em". The words of doom. I get there and sure enough there is nothing. Hang on, some Curlew, and something singing from a tree. It is probably the Pipit but I have no audio media with me and I have to wait to get home to discover that yes, it probably was, but it doesn't show and certainly doesn't do a parachute-song-flight thing, so it avoids being added to the year list.

And then something unexpected. Subsequently I find this is quite a good record for the site; its a male Marsh Harrier. And yes its nice to see but there are flocks of these things not far away.

Finally I get lost coming back to the path and end up being dumped out on a flat straight A road for the walk back to the car with drivers hurtling past at speed. Oh well. I'm sure there was nothing at Titchwell. Oh hang on, there was this.

Monday, June 13, 2016

Badbury Rings

Final stop, Badbury rings, an ancient hill fort. Now preserved for posterity by the National Trust. The rings have not been disturbed for ages, presumably since the Durotriges tribe dug them out, and is home to a variety of plants.

Common Spotted Orchid was everywhere in good numbers. Scattered amongst them, particularly on the southern sides, were Greater Butterfly Orchid. There were a few Bee Orchids showing too, a gorgeous deep pink.

Badbury rings wouldn't be famous for orchids if it were just these three orchids, and I think I found a Fragrant Orchid but it is just coming into bloom so a little early. The Frog Orchids I didn't find, but then neither did Aidan

2 Cuckoos flew past, and a Corn Bunting sang from the perimeter fence. A Small Blue and some Common Blues were amongst the butterflies seen.








I think those long spurs indicate Fragrant Orchid?

Left at 6pm with a really nice clear relaxed run up the M3 and M25 with some of the finest jazz-rock to have come out of the Netherlands in the first half of the 1970's on the player. Here's a sample.



Sunday, June 12, 2016

Paying Respects to the Naked Man

If you are interested in wildlife, and find yourself in early summer in Dorset with some hours to spare, then you really should go and pay your respects to the Naked Man.

And so to Cerne Abbas, a picture postcard village a few miles north-west of Dorchester, nestled amongst gentle rolling hills.

A typical house in Cerne Abbas.
The hills to the north west were the focus today, and in particular the south-facing slope, ancient meadows alive with butterflies. The commonest butterfly,  yes the commonest, was the fantastic Marsh Fritillary. Just everywhere, fluttering from dandelion to dandelion.


still struggling with the depth of field on the Macro Lens ...

Amongst them were other butterflies; Meadow Brown, some unidentified blues, Speckled Wood, and two skippers: the appropriately named Dingy Skipper and the spectacular Grizzled Skipper.

Dingy Skipper
Grizzled Skipper

And finally the man himself; the Cerne Abbas Giant. I was on the slope on the LHS of this picture. Common Buzzard on the right.


As a postscript, one way to ruin a day out is to immediately on your return google the place you've just been and see what others have seen here. Those Speckled Woods; they were quite well marked. Am I sure they weren't Duke of Burgundies?  Its too late now - no photographic evidence to review. Next time I will be prepared.



Friday, June 10, 2016

How far away is that bird?

bird-wise the Dorset trip finished with an atmospheric Arne reserve in the late evening on Tuesday, with several Nightjars churring away (but unfortunately not seen), and a brief but clear view of the Great-Spotted Cuckoo in flight at Portland Bill. Given the choice of spending a couple of hours hunting for the thing at a cold and windy fog-bound  Portland or heading off to find some sun I headed off. More of where I ended up in subsequent posts.

But back to that Goshawk sat in a tree. It was distant, just visible as a pale blob through the binoculars, then clearly identifiable as an accipiter with the scope turned up to 60x. But just how far away was it?

Technical data on the Kowa 883 is surprisingly difficult to find, but according to a review of the Kowa 883, the field of view at 60x is 1.1 degrees.  The bird filled about 10% of the viewer from top to bottom so that is 0.11 degrees, and the bird itself being a female is around 40 cm high.

So simple geometry is that the distance x times the angle a in radians gives the height h of the bird. Reversing that and dividing the height of the bird by the angle in radians gives the distance. So:

  •  0.11 degrees x pi/180 = 0.0024 radians. 
  • 40 cm/0.0024 = 166 metres.
So on that calculation the bird was 166 metres away. But there are quite a few sources of error on that. Firstly the FOV at 20x is 2.2 so by my simple calculations the FOV at 60x is 2.2/3 = 0.733 degrees. Perhaps the bird stands 50 cm high and it was only a 15th of the total top-to-bottom distance, so put those numbers in to the calculations and the distance becomes just over 500m. Put 1.1 degrees, 30cm and an eighth of the height and get 125m. So that's somewhere between 125 m and 500m with the middle calculation being 166m

From these calculations a rule of thumb is that at 60x and 10% of the view-finder height, a 10cm object = 50 m distance.

I don't think it was 125m away.  It was nearer the 500m, but maybe only 300?

Anyway, next time I'm in this position I'll think about the size of the image in the viewfinder and the likely size of the bird. Maybe do some tests of cars at a known distance. Something to work on ...

... and if you spot a simple mistake, please let me know in the comments section.

[updated with a correction]