Further Confirmation Of Arctic Sea Ice Dramatic Fall

Since early April, 2016, there have been problems with the sensor on the F-17 satellite that provided the data for many Arctic sea ice images. On April 12, NSIDC issued a notice that it had suspended the provision of sea ice updates. On May 6, NSIDC announced that it had completed the shift to another satellite. The red dotted line in the image below shows data from the F-18 satellite from April 1 to May 15, 2016.

The JAXA site also provides sea ice extent images, obtaining data from a Japanese satellite. They show that Arctic sea ice extent on May 15, 2016 was 11,262,361 square km, 1.11 million square km less than it was on May 15, 2012.

The Cryosphere Today is still using data from the F17 satellite, showing some weird spikes. Albert Kallio has taken a recent image and removed faulty spikes, resulting in the image below showing sea ice area up to May 3, 2016.

[ yellow line is 2016, red line is 2015 ]

Importantly, above image confirms that Arctic sea ice in 2016 has indeed been very low, if not at its lowest for the time of the year. Especially since April 2016, sea ice has fallen far below anything we've seen in earlier years. Below, Albert elaborates on comparing data.

by Albert Kallio‎ REPAIRED USA (F-17) SATELLITE DATA SHOWS RECORD SMALL SEA ICE AREA IN MAY 2016 AGREEING JAPANESE (JAXA) DATA A corrected Special Sensor Microwave Imager and Sounder (SSMIS) data set on the Defense Meteorological Satellite Program (DMSP) F-17 satellite that provides passive microwave brightness temperatures (and derived Arctic and Antarctic sea ice products) has been corrected here for the system instrumentation error. This agrees with the Japanese JAXA curve, and has been accomplished by removal of the uncharacteristic upward 'ice growth' spikes by linear intrapolation of the corrupt data points. This reinforces the JAXA data that shows the Northern Hemisphere sea ice area is seasonally at new record low which has continued in May 2016. Smoothened F-17 curve agrees with the Japanese JAXA satellite curve. The reconciliation of the two has been accomplished by removal of the uncharacteristic upward spikes by linear intrapolation of the corrupt days' data points which incorrectly showed immense sea ice area growth in the middle of spring melt season. This reinforces the JAXA data that shows the sea ice area is seasonally at record lows. Therefore, media who are citing recent F-17 satellite sea ice area figures are intentionally distorting the facts with their claims of the Northern Hemisphere having a record sea ice area for this time of season - whereas in reality - the exact opposite has been happening.

Arctic sea ice is in a bad shape and looks set to deteriorate even further, for a number of reasons.

The year 2016 is an El Niño year, as illustrated by the 51.1°C (124.1 °F) forecast for May 22, 2016, over the Indus Valley in Pakistan (see image right).

Insolation during the months June and July is higher in the Arctic than anywhere else on Earth. Greenhouse gases are at record high levels: CO2 was 408.2 ppm on May 12, 2016, and methane levels are high and rising, especially over the Arctic.

Ocean heat is also very high and rising. The image below shows that oceans on the Northern Hemisphere were 0.93°C (or 1.7°F) warmer in the most recent 12-months period (May 2015 through April 2016) than the 20th century average.

The situation is further illustrated by the image below, using the NOAA data with a trendline added that points at a rise of 3°C (5.4°F) before the year 2040.

Chances are that Arctic sea ice will be largely gone by September 2016. As the ice declines, ever more sunlight gets absorbed by the Arctic Ocean. This is one out of numerous feedbacks that are hitting the Arctic. The danger is that, as these feedbacks start to kick in more, heat will reach the seafloor of the Arctic Ocean and trigger methane to be released in huge quantities from the Arctic Ocean seabed.

Recently, an abrupt methane release from the Arctic Ocean seafloor did enter the atmosphere over the East Siberian Sea, showing up with levels as high as 2578 ppb (at 586 mb on May 15, 2016, pm, see image below). Such abrupt releases are indications that methane hydrates are destabilizing and are warnings that climate catastrophe is waiting to happen.

The situation is dire and calls for comprehensive and effective action as described in the Climate Plan.

Arctic Sea Ice gone by September 2016?

Arctic sea ice extent is very low, much lower than it was in other years at this time of year. On May 11, 2016, Arctic sea ice extent was 12.328 million square km, according to the National Snow and Ice Data Center (NSIDC), while JAXA's figure for extent on May 11, 2016, was only 11.57 million square km.

[ based in image from JAXA ]

JAXA figures show that Arctic sea ice extent on May 9, 2016, was 11.68 million square km, more than 18 days ahead on 2012 and 1.1 million square km smaller than it was on May 9, 2012.

The image on the right compares the Beaufort Sea and the northern part of Alaska between May 9, 2012 and May 9, 2016. As the image illustrates, there now is a lot less ice and snow cover than there was on 2012.

The situation looks set to deteriorate further over the coming months. The image below shows temperature forecast to reach anomalies as high as 5.19°C or 9.34°F for the Arctic as a whole (forecast for May 19, 2016, 0300 UTC), with temperature anomalies at the top end of the scale forecast for Alaska and eastern Siberia.

These temperature anomalies go hand in hand with a very wavy jet stream, as illustrated by the image on the right, showing loops extending all the way over the Arctic Ocean (in particular over the Beaufort Sea), taking along warm air in their path.

At the same time, the jet stream can extend far south at other places, making that cold air is moving south, out of the Arctic.

The result is a rapidly warming Arctic, which in turn makes the jet stream even more wavier, as one out of numerous feedbacks that are all  hitting the Arctic at the same time.

The image below compares sea ice thickness between May 13, 2012, and May 13, 2016.

The image on the right shows that sea surface temperatures near Svalbard were as high as 55°F (12.8°C) on May 11, 2016, an anomaly of 21.2°F (11.8°C) from 1981-2011. In other words, the temperature of the sea surface was 1°C in that spot from 1981 to 2011, and now this spot is 11.8°C warmer.

The image below compares sea surface temperature anomalies from 1961-1990 between May 12, 2015, and May 12, 2016.

Sea surface temperatures in the Arctic Ocean are higher than they used to be, in particular in the Bering Strait, the Beaufort Sea, in Baffin Bay and the Kara Sea.

[ click on images to enlarge ]

In summary, Arctic sea ice is in a very bad shape, while ocean heat is very high and rising. Greenhouse gas levels are at record high levels, as discussed in an earlier post and as further illustrated by the image below.

The image below shows that, over the past 365 days, warming over the Arctic have been much stronger than over the rest of the world. Air temperature anomalies of more than 2.5°C (4.5°F) show up over most of the Arctic Ocean. Furthermore, as discussed above, high temperatures are forecast to hit the Arctic over the next week.

From November 2015 to April 2016, global temperatures over land and oceans were 1.48°C (or 2.664°F) higher than in 1890-1910 (left map of the image below). On land, it was 1.99°C (or 3.582°F) warmer (right map of the image below).

[ also see comments ]

Since some 0.3°C (0.54°F) greenhouse warming had already taken place by the year 1900, warming was well above the 1.5°C (or 2.7°F) guardrail the Paris Agreement had pledged wouldn't be crossed.

Given the above, chances are that the sea ice will be largely gone by September 2016.

The situation is dire and calls for comprehensive and effective action, as described in the Climate Plan.

Wildfire Danger Increasing

Wildfires are starting to break out in British Columbia, Canada. The wildfire on the image below started on May 1, 2016 (hat tip to Hubert Bułgajewski‎).

The coordinates of the wildfire are in the bottom left corner of above map. They show a location where, on May 3, 2016, it was 26.0°C (or 78.8°F). At a nearby location, it was 27.6°C (or 81.8°F) on May 3, 2016. Both locations are indicated on the map on the right.

These locations are on the path followed by the Mackenzie River, which ends up in the Arctic Ocean. Wildfires aggravate heat waves as they blacken the soil with soot. As the Mackenzie River heats up, it will bring warmer water into the Arctic Ocean where this will speed up melting of the sea ice.

Moreover, winds can carry soot high up into the Arctic, where it can settle on the sea ice and darken the surface, which will make that more sunlight gets absorbed, rather than reflected back into space as before.

The danger of wildfires increases as temperatures rise. The image on the right show that temperatures in this area on May 3, 2016 (00:00 UTC) were at the top end of the scale, i.e. 20°C or 36°F warmer than 1979-2000 temperatures.

Extreme weather is becoming increasingly common, as changes are taking place to the jet stream. As the Arctic warms up more rapidly than the rest of the world, the temperature difference between the Equator and the North Pole decreases, which in turn weakens the speed at which the north polar jet stream circumnavigates the globe.

This is illustrated by the wavy patterns of the jet stream in the image on the right, showing the situation on May 3, 2016 (00:00 UTC), with a loop bringing warm air high up into North America and into the Arctic.

In conclusion, warm air reaching high latitudes is causing the sea ice to melt in a number of ways:

• Warm air makes the ice melt directly. 
• Warmer water in rivers warms up the Arctic Ocean. 
• Wildfires blacken land and sea ice, causing more sunlight to be absorbed, rather than reflected back into space as before.  

[ click on images to enlarge ]

The situation doesn't appear to be improving soon, as illustrated by the image on the right. Following the record high temperatures that hit the world earlier this year, the outlook for the sea ice looks bleak.

Further decline of the snow and ice cover in the Arctic looks set to make a number of feedbacks kick in stronger, with methane releases from the seafloor of the Arctic Ocean looming as a huge danger.

NSIDC scientist Andrew Slater has created the chart below of freezing degree days in 2016 compared to other years at Latitude 80°N. See Andrew's website and this page for more on this.

Below is a comparison of temperatures and emissions for the two locations discussed above. Such fires are becoming increasingly common as temperatures rise, and they can cause release of huge amounts of carbon dioxide, carbon monoxide, methane, sulfur dioxide, soot, etc.

May 3, 2016, at a location north of Fort St John, British Columbia, Canada.

May 4, 2016, near Fort McMurray, Alberta, Canada.

The video below shows methane levels (in parts per billion or ppb) on May 3, 2016, pm, starting at 44,690 ft or 13,621 m and coming down to 5,095 ft or 1,553 m altitude. In magenta-colored areas, methane is above 1950 ppb.

In the video below, Paul Beckwith discusses the situation.

Wildfires are also devastating other parts of the Earth. Below is an image showing wildfires over the Amur River on May 7, 2016.

The image below shows carbon monoxide levels over the Amur River as high as 22,480 ppb on May 9, 2016. Hat tip to Grofu Antoniu for pointing at the CO levels. According to this Sputniknews report, a state of emergency was declared in the Amur Region as fires stretched across 12,200 acres.

The video below shows carbon monoxide emissions in eastern Asia from May 1 to May 26, 2016.

Meanwhile, the National Snow and Ice Data Center (NSIDC) has resumed daily sea ice extent updates with provisional data. The image below is dated May 5, 2016, check here for updates.

As illustrated by the image below, from JAXA, sea ice extent on May 6, 2016, was under 12 million square km, more than 15 days ahead on extent in the year 2012, which was 12 million square km on May 21, 2012.

The situation is dire and calls for comprehensive and effective action as described in the Climate Plan.

Malcolm Light comments: Most natural processes on the Earth are run by convection including plate tectonics that moves the continental and oceanic plates across the surface of the planet. Mother Earth has been able to hold its atmospheric temperature within certain limits and maintain an ocean for more than 3 billion years because each time there was a build up of carbon dioxide in the atmosphere which produced a global fever, Mother Earth it eliminated the living creatures with a massive Arctic methane firestorm that fried them alive. This giant Arctic methane firestorm is a natural antibiotic the Earth uses to rid itself of those creatures that have overproduced carbon dioxide and caused a global fever. Essentially mankind has again caused a massive build up of fossil fuel carbon dioxide in the atmosphere and Mother Earth has already started to respond with the predicted massive Arctic methane blow out (since 2010) which will lead to an Earth engulfing firestorm in 5 to 8 years. The giant fires in the Fort McMurray region are a result of atmospheric methane induced heating of the Arctic and 93.5% global warming of the oceans that has generated a massive El Nino event this year. Hot winds moving away from these high pressure areas have generated high temperatures and massive fires in Alberta which is a giant fever spot on Earth where mankind has produced the maximum amount of dirty fossil fuel extraction and pollution in Canada. Mother Earth will continue to respond more vigorously with her Arctic methane antibiotic to eliminate the humans from her system as we represent nothing more to her than a larger version of an influenza virus which has seriously retarded her oceanic and atmospheric temperature range functioning systems. If we do not immediately stop fossil fuel extraction worldwide and control the Arctic methane emission sites we will all be stardust before a decade is past.

Links

• The Threat of Wildfires in the North
http://arctic-news.blogspot.com/2013/06/the-threat-of-wildfires-in-the-north.html

• Smoke Blankets North America

http://arctic-news.blogspot.com/2014/07/smoke-blankets-north-america.html

• Wildfires even more damaging
http://arctic-news.blogspot.com/2013/07/wildfires-even-more-damaging.html

• Wildfires in Canada affect the Arctic
http://arctic-news.blogspot.com/2013/07/wildfires-in-canada-affect-the-arctic.html

2016 Heat Felt Around Globe

created by Sam Carana with JAXA image

Above image shows that 2016 Arctic sea ice extent has been very low, if not at record low, up to April 30, 2016. This situation doesn't appear likely to improve, due to high ocean heat causing melting from below and high air temperatures that cause melting from above and that also cause water to warm up in rivers ending up in the Arctic Ocean.

The image below shows that on April 28, 2016, sea surface off the coast of North America was as much as 12.3°C or 22.1°F warmer than in 1981-2011. The Gulf Stream will make that much of this heat will arrive in the Arctic Ocean over the next few months.

The image below compares April 30 sea surface temperature anomalies between 2015 (left panel) and 2016 (right panel), showing that the sea surface in many areas is warmer in 2016 than it was in 2015.

Next to sea surface temperatures, air temperatures are rising, as illustrated by the image on the right, showing temperatures over Alaska as high as 14.6°C or 58.4°F at 64.5°N and as high as 10.8°C or 51.4°F at 66.5°N on May 1, 2016. Such rising temperatures over land will warm up rivers that will in turn warm up the Arctic Ocean.

The Google reference map below shows a large part of the Arctic Ocean, including Alaska on the left and the Beaufort Sea at the bottom. The map has an added red square inset that indicates the outlines of the map further below, which zooms in further on the Beaufort Sea.

The April 26, 2016, NASA map below shows that, while it is in places still relatively thick, the sea ice in the Beaufort Sea is strongly fractured with much water showing up in the fractures, and even more water along the coast.

Worryingly, high methane peaks have been recorded recently, as high as 2810 ppb on April 29, 2016, as illustrated by the image below, showing a large area with high methane levels east of Greenland.

Meanwhile, the heatwave in South-East Asia continues, with temperatures as high as 49°C or 120.1°F recorded on April 27, 2016, as illustrated by the image on the right.

As the image below shows, temperatures do not appear to be coming down, with temperatures as high as 49.4°C or 120.8°F forecast to hit India on May 2, 2016 (at the location marked by the green circle).

As global warming continues, this will make humidity levels rise. A 3°C warming will cause about 25% increase in absolute humidity, which will make it feel at least 6°C hotter. Moreover, water vapor is a potent greenhouse gas, further accelerating global warming.

The situation is dire and calls for comprehensive and effective action, as described at the Climate Plan.

More and more extreme weather

The weather is getting more and more extreme. On April 23, 2016, temperatures in India were as high as 47.7°C or 117.9°F. At the same time, temperatures in California were as low as -12.6°C or 9.2°F, while temperatures in Greenland were as high as 3.6°C or 38.6°F. Meanwhile, Antarctica was as cold as -60°C or -76°F.

The situation in India is most worrying. Temperatures are very high in many locations. India has been experiencing heatwave conditions for some time now, as reported in this and in this earlier posts.

[ click on images to enlarge ]

More extreme weather goes hand in hand with changes that are taking place to the jet stream, as also discussed in earlier posts (see further below).

As the Arctic warms up more rapidly than the rest of the world, the temperature difference between the Equator and the North Pole decreases, which in turn weakens the speed at which the north polar jet stream circumnavigates the globe. This is illustrated by the wavy patterns of the north polar jet stream in the image on the right.

The outlook for the next week shows the north polar jet stream move higher over the arctic, and to eventually disintegrate altogether, while merging with the subtropical jet stream over the Pacific Ocean.

The video below shows how a very wavy jet stream is projected to disintegrate over the Arctic Ocean over the coming week.

This makes it easier for warm air to move into the Arctic and for cold air to move out of the Arctic, in turn further decreasing the temperature difference between the Equator and the North Pole, in a self-reinforcing feedback loop: "It's like leaving the freezer door open."

Temperature forecasts for the Arctic Ocean are high, with anomalies projected to be above 4°C for the Arctic over the coming week.

The image on the right shows one such forecast, projecting a temperature anomaly of 5.31°C or 9.56°F for the Arctic on April 27, 2016, 1500 UTC, while an earlier forecast projected a 5.34°C or 9.61°F anomaly (hat tip to Mark Williams).

The danger is that the combined impact of high air temperatures and ocean heat will cause rapid demise of Arctic sea ice over the next few months.

On April 22, 2016, the sea surface was as much as 11.3°C or 20.3°F warmer than 1981-2011 (at the location off the coast of North America marked by the green circle).

High ocean heat is further accelerating Arctic sea ice demise, as the Gulf Stream keeps carrying ever warmer water into the Arctic Ocean. The image below, created with an image from the JAXA site, shows that Arctic sea ice extent was well under 13 million km² on April 19, 2016, and about 1 million km²  less than the extent in the year 2012 around this time of year.

Demise of the sea ice will cause even more rapid warming of the Arctic Ocean, with the danger that more heat will penetrate sediments that contain huge amounts of methane in the form of hydrates and free gas, threatening to trigger huge methane releases and cause runaway warming.

Methane levels are increasing strongly. This may not be as noticeable when taking samples from ground stations, but the rise is dramatic at higher altitudes, as also discussed earlier in this post and in this post.

Methane levels in ppb (parts per billion, at bottom of image)

The situation is dire and calls for comprehensive and effective action, as described at the Climate Plan.


Related

- What's wrong with the weather?

http://arctic-news.blogspot.com/2014/07/whats-wrong-with-the-weather.html

- How melting Arctic ice is driving harsh winters - by Nick Breeze
http://arctic-news.blogspot.com/2014/11/how-melting-arctic-ice-is-driving-harsh.html

- Wild Weather Swings 

http://arctic-news.blogspot.com/2014/10/wild-weather-swings.html

- Record Arctic Warming
http://arctic-news.blogspot.com/2016/04/record-arctic-warming.html

Can we Design Hydrogen-Fuelled Aircraft?

Can we Design Hydrogen-Fuelled Aircraft?

S H Salter, Engineering and Electronics, University of Edinburgh.EH9 3JL.

The collection of temperature measurements by David Travis following the 3-day grounding of all US civilian flights after 9/11 showed the astonishing effect of jet exhaust on the environment. If burning hydrocarbon fuel in the stratosphere ever becomes a criminal offence, the aviation industry will have an interesting problem. A possible solution is the use of hydrogen as a fuel. Is this technically possible?

The Airbus 380 carries 250 tonnes of fuel with a total calorific value of about 1013 joules. Fuel is stowed in wing tanks but this would be a volume of about one eighth of the fuselage. The calorific value per unit mass of hydrogen is about 3.5 times that of jet fuel and so the weight of hydrogen for the same range would be only about 70 tonnes. Unfortunately the ratio of density of jet fuel to un-pressurized hydrogen is about 9000, so the design problem is how to reduce the volume ratio by about 2500. If we compress hydrogen to reduce its volume by a factor of, say, 100 we still have a fuel volume of 25 times the liquid fuel one or 3.2 times the fuselage volume. The cube root of 3.2 is 1.47 so by increasing all three fuselage dimensions by this factor we could have an aircraft with enough volume for all fuel in the fuselage but no passenger space. An increase by a factor of about 1.6 in both diameter and fuselage length would give enough volume for passengers provided they did not feel unhappy about being close to so much hydrogen.

The immediate reaction against the proposal will be triggered by embedded folk memories of the Hindenburg. Any use of hydrogen will need careful public relations. The Hindenburg survival rate was 64%, much better than crashes of modern conventional aircraft. Deaths were caused by jumping not burning. People who stayed aboard until the wreck reached the ground were unharmed. It is likely that the fire started in the fabric dope rather than the hydrogen. Because spilt hydrogen moves rapidly upwards there is much less risk than from a liquid fuel or heavier-than-air gases like butane or propane which regularly cause devastating explosions in boats and buildings. Furthermore the heat radiated by the invisible hydrogen flame is much lower than that from carbon particles in hydrocarbon flames. We can argue that hydrogen is actually safer than jet fuel, petrol and hydrocarbon gases.

We can spend the 180 tonne fuel weight-saving on gas storage bottles in the form of a low-permeability skin surrounded by wound carbon fibres. A helical winding of aluminium sheet with a low diffusion coefficient for hydrogen looks good. It can be made with the linear equivalent of spot welding. The axial stress in a thin-wall tube under pressure is only half the hoop stress, so we can use the gas tubes as fuselage strength-members. Once the fuselage bending moments are known, we can choose the wrap angle of the windings to give the right balance of directional strength. One structure might be a bundle of nine tubes in a hexagonal array with six full of hydrogen and three containing passengers. A cross section is sketched in the figure. Other configurations are being studied.

The smooth stress paths of the gas bottles would be badly disrupted by the conventional design of landing gear. Can we get rid of it? The requirements for processing the variable energy flows from renewable-energy sources have led to the development of new high-pressure oil machines using digital rather than analogue control of machine displacement. These machines have very high conversion efficiencies and very easy interfaces to computers (see http://www.artemisip.com/ ) . The extremely accurate control of very large energy flows allows many new applications. One of these involves replacing the landing gear of large passenger aircraft with a ground vehicle. Please suspend disbelief until you have considered the following facts:

1. The landing gear of the A380 weighs 20 tonnes, say, 200 passengers. This weight is carried round the world for many hours and then used for only a few minutes on each flight.
2. The landing gear occupies a substantial volume of the internal space. The volume restriction limits the travel of the landing gear and so increases acceleration forces.
3. The requirement for openings compromises the structural integrity of the fuselage and adds weight, even more passengers.
4. Landing gear must perform with very high reliability despite the weight penalty and extreme temperature cycling.
5. The full weight of the aircraft must be passed to the ground through highly stressed points.
6. Gas turbines are very inefficient for moving aircraft on the ground at slow speeds.
7. On the A380 the shape of the landing gear doors and opening spoils the aerodynamic fairness. 
8. There is a severe design conflict between tyre weight, tyre life and braking performance.

An alternative might be to provide the function of the landing gear by a special-purpose ground vehicle. It would of course have to have VERY reliable links to the aircraft ground approach electronics so as to be in exactly the right place and moving with the right velocity underneath an aircraft on final approach. However there would be no weight, volume or temperature compromises.

The contact between the landing vehicle and the aircraft would be provided by a nest of large air-filled tubes like very large, very soft V-block, running the full length of the fuselage. This would spread the weight evenly into the aircraft skin. The tube surfaces could have vacuum suckers, like an octopus, which could apply shear forces evenly to the aircraft skin. The bags could be on a frame which could have hydraulic actuators to give a much longer travel than the legs of the landing gear. Tilting this frame would remove the need for the angling of the rear underside of the fuselage required to prevent ground contact at V-Rotate. This would further reduce drag during flight. The absence of fuselage penetrations could allow safe water landings for emergency. Runways can have parallel lakes presenting a much lower fire hazard if fuel is spilt. The impact loading on the runway would be much reduced and it might even be possible to revert to grass runways with several parallel operations from any wind direction.

The ground vehicles could use Diesel engines with much higher efficiency at taxi speed than gas turbines. They could have higher acceleration during take off and higher deceleration during landing. The hydraulic transmission would also allow regenerative braking, so the kinetic energy from one landing could be used for the next take-off. All-wheel steering and the option of direct side movement would allow much better use of ground space. The ground vehicle could have many more tyres, which need have no weight or volume compromise to achieve high braking. It could have an air-knife to dry runway surfaces and remove snow. There would be plenty of time to inspect and exchange landing vehicles and they would be in use for a much higher fraction of the time. The landing vehicles could gently lower aircraft on to passive supports at each loading pier and be used for other movements while aircraft were being boarded or serviced.

Images by S H Salter, University of Edinburgh.

The volume of most aircraft wings is much below that of the fuselage and so there is not a strong reason to use gas tubes as structural wing members. However they would offer a way to offset the extra drag of the larger frontal cross-section. From the original work by Prandtl, it has long been known that sucking air from the upper surface of an aerofoil section will reduce the drag by an amount which far offsets the power needed for a suction pump. Schlichting in figure 14.9 of Boundary Layer Theory gives a graph showing a factor of more than two. An objection to suction on wings, where the outer skin is a structural member, is that perforations and slits cause stress concentrations. This should not apply to wing spars made as gas tubes supporting an unstressed skin.

It is important that using fuel does not move the centre of gravity of the aircraft. This happens automatically with fuel stowed in wing tanks. If large quantities of fuel are to be stored in the fuselage it will be necessary to have the centre of pressure of the wings close to the centre of gravity of the fuselage-engine combination. The choice of a ground-based landing vehicle suggests high wings and engine placement above the wing. In theory at least, this will give some advantage from higher air-velocity over the upper wing surface and lower noise transmission to ground level. It is much easier to service and inspect equipment if you do not have to reach above your head. Cranes lifting an engine upwards are much more convenient than forklift trucks working from below. While some change in the architecture of maintenance hangers would be required, high engines accessed from above would by no means be unwelcome to ground crew.

Gas tubes may not be ideal for connections to a low-chord wing and so the longer attachment line of a delta wing, such as used in the Vulcan and Concord and many fighter designs, should be investigated. A flat underside will relax the requirement for precision in yaw during landing. Suction may be able to offset some of the disadvantages of the delta wing as applied to civilian aircraft provided always that they can land safely after a failure of the suction system. A delta wing with a deep thickness and a leading edge made from very strong but transparent material, perhaps poly carbonate, might even allow passengers to sit in the wing enjoying a splendid view if their vertigo allows.

The range of the A 380 is 15,000 kilometres. While this may have been chosen for passenger convenience with the properties of present fuels, it is larger than necessary for trans-Atlantic flights and could allow a further volume reduction. The San Francisco to Sydney distance is only 12000 km and stops in mid Pacific could be very attractive.

Before we waste time on radical new aircraft designs and ground-based landing systems, it is necessary to confirm that burning hydrogen in gas turbines at high altitudes will be a chemically appropriate solution. If we burn hydrogen in ambient air there will be no release of carbon dioxide but there will still be the formation of nitrogen–oxygen compounds collectively known as NOXes. If these are cooled very rapidly, as in the adiabatic expansion of an internal combustion engine, they can be ‘frozen’ at the high-temperature equilibrium state with lots of very nasty acids. The lower combustion pressure and slightly slower cooling of a jet exhaust should be less severe but we want to quantify the severity of the problem. There may even be problems from ice crystals formed from the exhaust. I have asked colleagues at the National Centre for Atmospheric Research at Boulder Colorado for an opinion.

There is one engine design in which the combustion products cool slowly enough for almost all the NOX production to revert to ambient values. This is the Stirling engine originating from 1815 but abandoned because of the absence of materials with good thermal conductivity and high hot strength. Much better materials are now available. By an extraordinary coincidence, the digital hydraulic systems needed for the speed and accuracy of the ground-based landing gear can also radically change the design of Stirling engines by using hydraulics to replace the crank and connecting rods of the conventional Stirling engine. A Stirling-engined aircraft would probably have to use a ducted fan or propeller propulsion but these could still allow civilian aviation to continue in a NOX-sensitive world.

The best way to do experiments on high-altitude engine-chemistry might be from a balloon. Do we know anyone with an interest in this area?

March temperature

Above image shows Land-Ocean (in red) and Land-only (in black) global monthly temperature anomalies compared to the average over the period 1951-1980.

At the Paris Agreement, nations committed to strengthen the global response to the threat of climate change by holding the increase in the global average temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels.

To see how much temperatures have risen compared to pre-industrial levels, a comparison with the period 1951-1980 does not give the full picture. The image below, created by selecting a smoothing radius of 1200 km, shows that the global temperature rise from 1890-1910 was 1.58°C or 2.84°F.

The temperature rise is even higher when looking at measurements from land-only stations. The image below compares the March 2016 temperature with the period from 1890-1910 (250 km smoothing), showing a Land-only anomaly of 2.42°C or 4.36°F.

Taking into account that temperatures had already risen by some 0.3°C (0.54°F) before 1900, this adds up to a total temperature rise on land in March 2016 of 2.72°C (4.9°F) from the start of the industrial revolution.

On the Northern Hemisphere, there was an even more dramatic temperature rise on land. In March 2016, on land on the Northern Hemisphere, it was 4.9°F or 2.72°C warmer than the 20th century average, as illustrated by the image below.

How much of this rise can be attributed to El Niño? One way to answer this question is by adding a polynomial trend, as in the March Northern Hemisphere Land Temperature Anomaly image below, showing that temperatures had already risen by 2°C in March 2015, while pointing at a rise of 4°C by March 2030 and 10°C before the year 2050.

The trendline also shows that a temperature difference of about half a degree Celsius between the 20th century average and the year 1900. Taking into account that temperatures had already risen by some 0.3°C (0.54°F) before 1900, this adds up to a total temperature rise on land on the Northern Hemisphere in March 2016 of 3.52°C or 6.34°F from the start of the industrial revolution.

NOAA data show that in March 2016, it was 2.33°C or 4.19°F warmer on land globally than the 20th century average. When compared to temperatures around the year 1900, it was even warmer.

In February 2016, NASA data show that it was 2.33°C or 4.19°F warmer on land (with 1200 km smoothing) than it was in 1890-1910, while it was 2.48°C or 4.46°F warmer for a 250 km smoothing radius for the land-only data. In an earlier post, a 2.3°C rise in February 2016 was used as one of several elements making up the total rise that could eventuate on land by the year 2026, assuming that no geoengineering will take place (image below).

Meanwhile, the current El Niño is still going strong and causing very high temperatures, making one wonder how high temperatures will be during the next El Niño, which could eventuate a decade or less from now. The image below shows high temperatures at four locations in South-East Asia on April 20, 2016.



The situation is dire and calls for comprehensive and effective action, as described in the Climate Plan.