Monday, 30 June 2014

Blue sky thinking

Photo: Clive Simpson
Researchers concerned about the climate change potential of condensation trails in the sky caused by aircraft have suggested the impact could be reduced by re-routing flight paths.

Contrails - a cirrus-like cloud - are a relatively new type of high-level cloud that appear in the wake of high-altitude aircraft as water vapour from engine exhausts coalesces.

They can be up to 150km in length and last up to 24 hours, forming when planes fly through very cold and moist air causing engine exhausts condense into a visible vapour.

Founder of The Cloud Appreciation Society Gavin Pretor-Pinney writes in The Cloudspotter’s Guide that we may be surprised to learn that contrails are even classified as clouds.

But clouds they are - and the only difference between them and what nature produces is that contrails are definitely man-made.

Contrails reflect sunlight back into space and so have a cooling effect - but they also trap infrared energy in the atmosphere, which adds to global warming.

Scientists at the University of Reading in the UK have been looking at how the warming impact - which is more significant overall than the cooling - could be reduced by altering the flight paths of long and short haul aircraft.

Previous work has suggested that planes could fly at lower altitudes to limit the trails but this would burn significantly more fuel and adding to CO2 emissions overall.

The Reading study attempted to see if the benefits of curbing contrails would outweigh the extra fuel burned if flights were re-routed whilst at the optimum flying altitude.

They suggest that avoiding the creation of a major contrail on a flight between New York and London would only add 22km to the journey but could curb the flight’s warming impact.

"You think that you have to do some really huge distance to avoid these contrails," said Dr Emma Irvine, the study’s lead author.

"But because of the way the Earth curves you can actually have quite small extra distances added onto the flight to avoid some really large contrails."

The researchers found that short haul aircraft are more fuel efficient and can add up to 10 times the length of the contrail to their journeys and still reduce overall warming potential.

So, if a flight from the UK to Spain is predicted to create a 20km long contrail, as long as the plane flew less than 200km extra to avoid it, the overall warming impact would be reduced.

But for large planes on longer routes over oceans and unpopulated areas - which offer more flexibility to minimally alter flight paths - this reduces to three times the contrail length.

"The key things you need to know are the temperature of the air and how moist it is, these are things we forecast at the moment, so the information is already in there," said Dr Irvine.

On average, 7% of the total distance flown by aircraft is in the type of air where long lasting contrails form but none of the calculations on the impact of aviation on global warming currently include them.

The carbon restrictions being introduced from 2017 for long haul flights originating or arriving in the EU will not include this significant source of warming from aviation.

"The mitigation targets currently adopted by governments all around the world do not yet address the important non-CO2 climate impacts of aviation," said Dr Irvine.

"Contrails may cause a climate impact as large, or even larger, than the climate impact of aviation CO2 emissions.

"We believe it is important for scientists to assess the overall impact of aviation and the robustness of any proposed mitigation measures in order to inform policy decisions. Our work is one step along this road."

Four years ago when flights across Europe were grounded - due to the dust cloud created during the eruption of an Icelandic volcano - our skies and sunsets could be viewed without visible signs of human intrusion.

Contrails and their delicate linear patterns often add a seemingly innocent beauty to the skies above but Pretor-Pinney is not so sympathetic and describes them as "the bastard sons" of the cloud family.

"They may cut dashing figures across the rosaceous autumn evening but these icy swathes of progress must be the writing on the sky for cloudspotters and everyone else besides," he says.

The Lighthouse Keeper is written by Clive Simpson - for more information, commission
enquiries or to re-publish any of his articles click here for contact information

Tuesday, 17 June 2014

New North Sea harvest

wind farm, renewables, north sea

Just as the UK's gas and oil bonanza is drawing to a close it seems that the often maligned North Sea off the east coast of Britain is about to deliver again.

This time the harvest will be in the shape of electricity from the gusty winds that ply relentlessly across the busy stretch of water.

The government announced today the go-ahead for one of the world's largest offshore wind farms that is set to be built off the coast of East Anglia.

‘East Anglia One’ will cover an area of 300 square kilometres in the southern North Sea and support almost 2,900 jobs and is expected to generate enough electricity to power the equivalent of 820,000 homes.

It could also pump over £520 million into the region’s economy and today’s announcement is an important milestone for the 50/50 joint venture between ScottishPower Renewables and Vattenfall,.

Construction is expected to start in 2017 with offshore installation commencing the following year and generation starting in 2019.

Initial plans were to install up to 325 offshore turbines in a zone some 43 km off the coast but the use of larger turbines means that only around 240 will likely be needed to deliver the same 1.2GW of capacity.

UK energy secretary Ed Davey said: “East Anglia and the rest of the UK have a lot to gain from this development. The project has the potential to inject millions of pounds into the local and national economies, and support thousands of ‘green’ jobs.

“Making the most of Britain’s home grown energy is crucial in creating job and business opportunities, getting the best deal for customers and reducing our reliance on foreign imports.”

RenewableUK’s chief executive Maria McCaffery described it as “a huge confidence boost” for the UK’s entire offshore wind sector.

“Our world-beating offshore wind industry is set to more than treble in size by the end of the decade – projects like this will help us to maintain our global lead,” he said.

“This marks the start of what is set to be one of the world’s major green energy infrastructure developments. It is the first of six projects within the same zone with a combined capacity of up to 7.2 gigawatts, enough to power more than 4.6 million British homes.

The government announcement stressed that the new wind farm would be ‘significantly larger’ than the the London Array, currently the biggest wind farm in the world.

ScottishPower Renewables and Vattenfall will now accelerate supply chain contracts and start detailed negotiations to determine which ports could best support the project.

Geographically, the North Sea - most of which has an average depth of around 94m - is on the European continental shelf and, strictly speaking, is part of the Atlantic ocean.

It lies between Norway and Denmark in the east, Scotland and England in the west, and Germany, the Netherlands, Belgium and France in the south.

Drilling for oil - in fields mostly owned by the UK and Norway - began in the 1960s and led to still on-going arguments between England and Scotland about how revenue from the oil should be spent.

In contrast to oil and gas, wind power is both sustainable and clean in terms of emissions and is now recognised as one of the world's fastest growing energy sources,.

Harnessing its power to make electricity won’t solve the world’s climate change problems but developments like East Anglia One are definite steps in the right direction.

The Lighthouse Keeper is written by Clive Simpson - for more information, commission
enquiries or to re-publish any of his articles click here for contact information

Thursday, 12 June 2014

Countdown to El Nino

Photo: Clive Simpson
Meteorologists and climate scientists say the world is likely to enter another El Niño weather event by this autumn upsetting 'normal' weather and driving up global temperatures further.

El Niño’s most notable characteristic is the presence of extra-warm surface water in the central and eastern equatorial Pacific ocean which tends to lead to greater average global temperatures.

Climate scientists saw a chance for 2014 to be a record temperature year even before news about the likely development of El Niño conditions - simply because temperatures continue to tick upwards.

“I would have predicted a likely top five if asked at the beginning of this year and the incipient/potential El Niño strengthens that,” said Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, one of the leading agencies that tracks global temperatures and ranks them by year.

“We saw record global temperatures in 1998, 2005 and again in 2010 when ongoing global warming was positively reinforced by El Niño events,” he added.

“There is a good chance we will see a global temperature record this year or next if a substantial El Niño event takes hold.”

Data from ocean observing satellites and other ocean sensors indicate that El Niño conditions appear to be developing in the equatorial Pacific Ocean.

Conditions in May 2014 bear some similarities to those of May 1997, a year that brought one of the most potent El Niño events of the 20th century.

The maps above show the ten day average of sea surface height centred on 2 May 1997 (left), and 3 May 2014. Darker shades indicate where the water is warmer and above normal sea level. Shades of blue-green show where sea level and temperatures are lower than average. Normal sea-level conditions appear in white. The 1997 map is from data collected by the TOPEX/Poseidon satellite, while the 2014 data is from the Ocean Surface Topography Mission/Jason 2 satellite.

During an El Niño, easterly trade winds in the Pacific falter and allow giant waves of warm water - known as Kelvin waves - to drift across from the western Pacific toward South America.

Surface waters in the central and eastern Pacific become significantly warmer than normal, altering weather patterns and affecting fisheries along the west coasts of the Americas. El Niño can also have a significant influence on weather and climate far from the tropics.

Sea surface height is a good indicator of the amount of heat stored in the water. As the ocean warms, the surface rises; as it cools, its falls. This is due to thermal expansion and contraction; the molecules in warmer water are farther apart than in cooler water.

Above-normal sea surface heights in the equatorial Pacific indicate El Niño conditions, while below-normal heights indicate La Niña.

“What we are now seeing in the tropical Pacific Ocean looks similar to conditions in early 1997,” said Eric Lindstrom, oceanography programme manager at NASA.

“If this continues, we could be looking at a major El Niño this autumn. But there are no guarantees.”

Observations from a network of sensors within the Pacific Ocean support the satellite view, showing a deep pool of warm water that has been sliding eastward since January.

The years 1997/98 brought El Niño out of the scientific literature and onto the front pages and evening newscasts. It was one of the strongest El Niño events observed, with extreme weather impacts on several continents.

North America had one of its warmest and wettest winters on record, particularly in California and Florida. Peru, Mexico, and the rest of Central and South America endured devastating rainstorms and flooding. Indonesia and parts of Asia saw disastrous droughts.

Scientists at the Climate Prediction Center of the National Weather Service (NWS) announced in early May that they foresee a 65 percent chance of a transition to El Niño in the summer of 2014.

"There remains uncertainty as to exactly when El Niño will develop and an even greater uncertainty as to how strong it may become," NWS reported.

All this might just be bad news for climate change skeptics. We've all heard by now the claim that global warming has ‘stopped’ or is ‘slowing down’ but this assertion often takes the very warm year of 1998 as the starting point.

By deliberately beginning with a hot year it can be made to look as though global temperatures aren't rising so fast.

Global temperature anomalies from 1950-2013 from World Meteorological Organisation, with years beginning with El Niño conditions in red and years beginning with La Niña conditions in blue.

You could think of annual global temperature variations as like waves on a rising tide. The rising tide is global warming and the waves are the shorter-term natural fluctuations related to phenomena like El Niño (or its flip-side La Niña), which warm (or cool) the globe by fractions of a degree.

The reality is that, as the World Meteorological Organisation (WMO) notes, each of the last three decades has been warmer than the previous one - culminating with 2001-2010 as the warmest decade on record.

Every time the world sets another temperature record, the global warming ‘slow down’ message becomes less compelling and as we enter another El Niño the climate change skeptics may finally be running low on options.

Either they finally accept the overwhelming body of evidence that global warming is real or they can come up with a new cherry-picked counter argument. Have a guess which one they'll choose - for now, at least?

The Lighthouse Keeper is written by Clive Simpson - for more information, commission
enquiries or to re-publish any of his articles click here for contact information

Monday, 9 June 2014

Tractors on the beach

The seaside town of Cromer lies on the UK’s east coast. Perched on the edge of crumbling north Norfolk cliffs, it is famous for tasty crabs, wide open beaches and a traditional Victorian pier complete with theatre and a seaside special variety show.

Its unique geographical location jutting out into the North Sea means that on a blue sky summer’s day you can watch both sunrise and sunset over the ocean.

This does imply, of course, that you are diligent enough to rise exceptionally early and still be wakeful enough at the other end of the day to repose on the pier, perhaps with beer in hand.

There is no quay-side or harbour at Cromer so the fishing boats are gathered on the shingle beach against the sea wall, each with its own tractor and boat trailer.

At the end of the 19th century, the beaches to the east and west of the pier were crowded with fishing boats. Now, you will see only a dozen boats which ply their trade from the east beach.

Crabs - dressed or undressed according to your state of desire - can be bought direct from local fishermen, or enjoyed at local restaurants in salads, tarts and sandwiches.

Today, it is not the crabs themselves that grab our interest but the rusty, salt-laden army of ancient and colourful tractors that line the beach head.

They are adorned and customised with all manner of fixtures and fittings - from plastic deckchairs as replacement seats to makeshift gear sticks and lashed on tarpaulins to keep the worst of the elements out of the workings.

Most look so rusted through with salt it seems a miracle their sand-blasted engines would ever start.

But somehow they defy mechanical odds and, with crabbing boats in tow, continue to chug across the shingle beach to the water’s edge and back.

The photos below are a selection from the Lighthouse Keeper's visit to Cromer on a sunny and warm afternoon a few days ago. All were taken with a Nikon D70 SLR camera.

All photos by Clive Simpson