What are the likely effects of climate change on the polar jet stream?

By Tom AndersonCandidate Number 4209

A dissertation submitted in fulfilment of the requirements for the qualification of:

AQA Extended Project Qualification (EPQ)

Supervised by:

Mr. P. J. C. Hicks

At:

The Perse SchoolCambridge

Centre Number 22133

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CONTENTS

Introduction………………………………………………………………...4

A background……………………………………………………………....4

Modern applications of the jet stream………………………........7

Recent weather trends………………………………………………..…9

The phenomenon of Arctic Amplification……………………….10

Arctic Amplification and the Polar Jet……………………………14

Alternative Interpretations……………………………………………15

Concluding Remarks………………………………………………….…17

Terminology………………………………………………………………..18

Image Credits……………………………………………………………...19

Bibliography ……………………………………………………………….20

well remember a brilliant red balloon which kept me completely happy for a whole afternoon, until, while I was playing, a clumsy movement allowed it to escape. Spellbound, I

gazed after it as it drifted silently away, gently swaying, growing smaller and smaller until it was only a red point in a blue sky. At that moment I realized, for the first time, the vastness above us: a huge space without visible limits. It was an apparent void, full of secrets, exerting an inexplicable power over all the earth’s inhabitants. I believe that many people, consciously or unconsciously, have been filled with awe by the immensity of the atmosphere. All our knowledge about the air, gathered over hundreds of years, has not diminished this feeling.

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Theo Loebsack, Our Atmosphere

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What are the likely effects of climate change on the polar jet stream?

Introduction

In this investigation, I will attempt to address a number of key issues in order to effectively answer my overall question, which concerns the likely effects of climate change on the polar jet stream. Firstly, an understanding of what is meant by the polar jet stream is necessary as there are many jets to potentially cause confusion, including weaker jets found in subtropical latitudes, barrier jets and valley exit jets found around mountain ranges (there have even been jet streams observed on Jupiter). I will seek to explore some of the modern day uses of the polar jet stream, and how these applications might be affected in future with the implications of climate change and rapid increases in temperature at the poles. Finally, I will evaluate the contemporary studies of the effects of climate change on the polar jet stream, and offer my own conclusions and predictions for the future of this exciting, cutting-edge topic.

Figure 1: Banded cirrus clouds running perpendicular to the jet stream—a tell-tale feature photographed by an astronaut aboard Space Shuttle Discovery.

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A background

There are a number of versions of who discovered the first jet stream, but we can be sure that aviation played a key role in its twentieth century discovery, as early World War Two American bomber pilots found they could hasten their transatlantic crossing by utilising a high-altitude, high-speed ribbon of air. The first appearance of a “jet stream” in modern literature was in 1939, when German meteorologist Heinrich Seilkopf1 used the term in a research paper. Interestingly, the Japanese had the idea to utilise a “great strong current of winter air”2 (the jet stream) flowing over their country during the war to carry tens of thousands of hydrogen balloons containing incendiary devices across the Pacific more than 8,000 kilometres with the intention of causing devastation to the U.S. mainland. Although extremely ineffective as weapons, six people were killed in Oregon, in what were the only casualties inflicted by the Axis powers on the American mainland in World War Two.

1 Hermann Flohn, Arbeiten zur allgemeinen Klimatologie. Darmstadt: Scientific

Buchgesellschaft, 1971. 31.2 John McPhee, Balloons of War. New York: The New Yorker, 1996. 52.

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Figure 2: A cross-profile through the atmosphere. Height (in miles and kilometres) is indicated along each side. Temperatures begin to increase again at the tropopause because of the presence of a sunlight absorber in the stratospheric air, ozone.

We live at the base of a soup of gases, constantly moving in all directions – the atmosphere. Virtually all of our weather occurs in the lower portion, the troposphere, which contains about 80% of the total mass of the atmosphere.3 As shown in Fig. 2 and 3, the troposphere extends from the Earth's surface to about 7 kilometres high at the poles and 17 kilometres high at the equator. As the density of the air in this layer decreases with height, the air temperature in the troposphere also decreases, from about 14 to 15 °C typically at the surface to about -45 °C at the top of the troposphere. Commercial jet aircraft cruise at the top of the troposphere, called the tropopause, at about 9-10km in altitude. The troposphere itself can even be divided into the planetary boundary layer (often visible as a haze, as pollution may build up in this area) and above that the free atmosphere (where clouds form.

Meanwhile, the stratosphere extends from the tropopause's height of 7 to 17 kilometres to a height of about 50 kilometres and contains about 19% of the atmospheric gases. 4 At the tropopause, there is a temperature inversion due to the build-up of ozone at this altitude; thus the stratosphere experiences increasing temperature and solar radiation with height. The stratosphere contains the ozone layer because the incoming solar radiation is increasingly absorbed by oxygen molecules in the stratosphere, leading to the oxygen molecule gaining an extra atom, forming ozone (O3). The ozone layer resides in the lower portion of the stratosphere, though the thickness of the layer varies seasonally and geographically. In addition, weather balloons can rise to about 40 kilometres (25 miles) before the difference between the pressure inside the balloon and the outside atmospheric pressure causes the balloons to expand to the point at which they burst.

3 National Weather Service, 'Layers of the Atmosphere' <http://goo.gl/i4l7aK>, 14 December 2007.4 Ibid.

Figure 3: (National Oceanic and Atmospheric

Administration)

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The polar jet stream itself is found at the tropopause (where the temperature inversion begins), the layer separating the troposphere from the stratosphere. The conventional wisdom among scientists as to why the polar jet stream is found here is that the temperature difference between the cold polar air and relatively warmer subtropical air is the greatest. But how does the temperature difference between two air masses cause the jet stream?

Since colder air is more dense than warmer air, there is an air pressure difference between them at any altitude. If the warm and cold air masses are quite deep (tall), higher altitudes in the atmosphere experience progressively larger air pressure differences. Since it is horizontal air pressure differences that causes wind, this can lead to very strong winds sometimes exceeding 200 miles per hour. But as you increase in altitude beyond the tropopause, the

temperature difference reverses, and as you ascend further the winds then decrease. The altitude at which the winds were strongest is considered to be the jet stream level.

In other words, the strongest jet stream winds occur between air masses having the largest temperature differences over the deepest layer of the troposphere - typically in the Northern Hemisphere’s winter, when the contrast between the frigid, sunless Arctic and the mid-latitudes should be at its greatest. Even though the wind ‘tries’ to flow from high pressure to low pressure, the Earth’s rotation causes the air flow to turn to the right in the Northern Hemisphere (the Coriolis effect), so the jet stream flows around the air masses, rather than directly from one to another. As a result, the jet stream does not ‘cause’ weather conditions of a certain type to occur. The jet’s existence is the result of suitable conditions (a large temperature contrast between the polar and subtropical air masses), and can be thought of more as a ‘conveyor belt’ transporting weather systems to the UK from the North Atlantic.

Figure 5: A cross-section through the atmosphere of the Northern Hemisphere. Equatorial regions are heated the most by the sun due to the high density of the sun’s incident rays, and so air rises at the Intertropical Convergence Zone (ICTZ). It is then advected (transported horizontally) to the north via the Hadley and Ferrel Cells (separated by a relatively weak subtropical jet stream) before meeting

cold polar air at the polar front, where the polar jet stream is located.

Figure 4: A typical weather balloon sounding plotted onto a chart showing atmospheric pressure variability with height above sea level

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Modern applications of the jet streamThe jet stream and air travel

Jet stream winds have an important effect on airline operations and the planning of their business. Flight times may be improved in transcontinental and transoceanic flights by riding the jet stream, while flights in the other direction will do everything possible to avoid a 200mph headwind, diverting around the jet stream path under the guidance of oceanic air traffic controllers. Strong shears in the jet stream region can cause clear air turbulence (CAT) that may, under serious conditions, lead to material fatigue and even aircraft failure.5

Since roughly 44,000 crossings of the Atlantic Ocean are made every year by commercial aircraft, airlines and pilots have become very adept at planning their routes. Jet stream forecasts are released every twelve hours, where airlines then bid for a slot in the Organized Track System (NAT-OTS), which also changes twice daily taking account the shifting of the jet stream aloft.

5 John E. Oliver, Encyclopaedia of World Climatology (Berlin: Springer Science+Business Media, 2008) 438

Figure 6: An infographic visualising the air-traffic lane system over the North Atlantic.

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The end result is to provide the fastest possible route, minimizing headwinds and maximising tailwinds on the aircraft, resulting in much more efficiency by reducing the amount of fuel burnt and the amount of fuel carried on-board.

High-Altitude Wind Power (HAWP)The polar jet stream has also been the subject of studies and trials of harnessing the wind by the use of tether and cable technology to generate power. Although in practise this would be extremely difficult to achieve, one major scientific article about jet stream power has calculated that the total wind energy in the jet streams is roughly one hundred times the current global energy demand.6

Recent weather trends

6 Archer, Cristina L. and Ken Caldeira, 'Global Assessment of High-Altitude Wind Power', Energies (2009), 2 307-319

Figure 7: Airline routes across the Pacific between San Francisco and Tokyo following the most direct great circle (top), but following the jet stream (bottom) when heading eastwards.

Figure 8: An enormous helium-filled wind turbine will soon float over Alaska producing electricity for more than a dozen families living off the grid. Designed and built by MIT start-up Altaeros Energies, the turbine known as the BAT-Buoyant Airborne Turbine will attempt to harness the powerful jet stream winds.

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The year 2015 made climate history, shattering all temperature records, featuring intense heatwaves, exceptional rainfall, devastating drought and unusual tropical cyclone activity. According to World Meteorological Organisation statistics, that record-breaking trend is continuing into 2016.7

Heat

- Many countries saw intense heatwaves. The most devastating ones in terms of human impact were in India and Pakistan. Asia, as a continent, had its hottest year on record, as did South America.

- Western and Central Europe recorded an exceptionally long heatwave, with temperature crossing or approaching 40°C in several places. Several new temperature records were broken (Germany 40.3°C, Spain 42.6°C, UK 36.7°C).

- North West USA and Western Canada suffered from a record wildfire season, with more than 2 million hectares burned during summer in Alaska alone (an area slightly larger than the size of Israel).

Heavy rainfall

There were many cases of extreme rainfall last year:

- In Africa, Malawi suffered its worst flooding ever in January. The West coast of Libya received more than 90mm of rain in 24 hours in September, compared to the monthly average of 8mm.

7 World Meteorological Organisation, 'State of the Climate: Record Heat and Weather Extremes' <http://goo.gl/32yhVc>, 21 March 2016.

Figure 10: A collection of some climate-related headlines. Recent years have seen increased media interest in anthropogenic (human-induced) climate change, focusing on Arctic warming. Figure 9: NOAA infographic showing some recent unusual climatic events around the world

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The phenomenon of Arctic AmplificationThe Earth’s climate system is patently in a confused state of affairs, displaying a “clear human influence”8, with all sorts of aforementioned records being broken regularly. When considering global atmospheric circulation, there are all sorts of factors at play in such a complicated system, such as an unusually strong El Niño effect in recent years and Milankovitch cycles, but a question still remains as to how much of our recent bizarre weather is due to a recent phenomenon known as Arctic Amplification.

Since the 1950s, accurate measurements have been taken of the concentration of carbon dioxide (CO2) in the Earth’s atmosphere from the Mauna Loa Observatory in Hawaii. In 1958 when American scientist Charles Keeling originally began taking these measurements, the atmospheric concentration of CO2 was around 310 parts per million (ppm).9 Today, due to our intensive burning of fossil fuels for energy, industry, agriculture and transport; we are the first humans to breathe air of more than 400ppm CO2, as illustrated by Figure 11.

What’s more, with modern technological advances and discoveries, scientists have been able to delve deep into the Earth’s geophysical history as far back as millions of years through the analysis of tree rings and digging hundreds of metres down into polar ice cores where bubbles of CO2 have been trapped and preserved. Further examination of these records has enabled us to determine what the Earth’s temperature was like many epochs ago, and can be represented in this IPCC (Third Assessment) diagram:

8 United Nations Intergovernmental Panel on Climate Change, Fifth Assessment Report (Geneva: 2014) vi.9 Scripps Institution of Oceanography, The Early Keeling Curve, <http://goo.gl/Sj709H> 25 February 2016.

Figure 11: Keeling’s measurements were at the time a dramatic discovery, representing one of the most important geophysical records ever made.  

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Together, the plots show a clear positive correlation between increased levels of carbon dioxide in the atmosphere and a warmer temperature on Earth. They also confirm the notion that the amount of CO2 in the Earth's atmosphere, and the Earth's temperature itself, has fluctuated in a cyclical pattern through time. These cycles of cooling and warming are natural, and caused, over the last 800,000 years, primarily by cyclic changes in Earth's orbit (previously mentioned Milankovitch cycles), propagating alternating periods of warmth and periods of glaciations.

However, what this graph shows that is so concerning is that current levels of atmospheric CO2 far exceed even the highest levels of the past 500,000 years, and our global temperature is increasing in response to this additional greenhouse gas. Some analysts go as far as suggesting that despite our climate agreements and treaties such as the UNFCCC, humans have already ‘locked-in’ significant temperature rises in future. This suspicion appears justified when considering Fig. 12, as the Antarctic temperature still has a long way to ‘catch up’ with the increased CO2 pumped into our atmosphere, since the two measures are visibly closely interlinked. If we examine the recent data, it is clear that the Earth’s temperature is starting to catch up. According to the WMO, 15 of the 16 hottest years on record have occurred during the 21st century.10 Moreover, as this Figure 10 NOAA National Centers for Environmental Information, State of the Climate: Global Analysis for Annual 2015, <https://goo.gl/oOuHSW>, January 2016.

Figure 12: The 800,000 year record of atmospheric CO2 from Antarctic ice cores, and a reconstruction of temperature based on hydrogen isotopes in the ice.

The 2001 (when the AR3 Report was released) CO2 concentration of 392 ppm is represented by the blue star. Just fifteen years on, this number has surpassed 400.

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shows, it isn’t as simple as suggesting that warming is occurring at a uniform gradient from the poles to the tropics. A wide variety of local factors, such as the albedo of the region, influence the extent to which warming occurs. In some patches, sea surface temperatures have even been observed to be cooling, though the outlook does not look healthy for the polar regions in particular, showing the emerging signals of arctic amplification. Fig. 13 shows the high latitudes are not 1 degree warmer than pre-industrial levels (as is the global average) but more like 10, 11 or 12 degrees above normal.

Figure 14 shows this temperature anomaly data in a graph format, grouping slices of the earth into zonal bands of latitude. The data shows that apart from a period around World War Two, temperatures have varied consistently across the globe from around 1920 to 1980 (as shown by the lines running equidistant to one another in a group). However, after 1990, the temperature anomaly for the Arctic latitude band in particular (≈66° north of the equator) begins to show very different behaviour as temperatures begin to rapidly pick

Figure 13: Anomalies (departures from average) in surface temperature across the globe for February 2016, in degrees Celsius.

Figure 14: Temperature anomalies with latitude band.

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up relative to the rest of the world. Evidently, different parts of the planet respond at different rates to GHG emissions, and scientists are paying particular attention to the Arctic having considered the arctic amplification in Figure 14.

The process of heating in the Arctic regions is believed to be increasing ever more rapidly because of the significance of the albedo of the snow cover and ice. White, snow covered surfaces are poor emitters and absorbers of heat, reflecting as much as 90% of the sun’s radiation back out into the atmosphere and much of this into space.11 As sea temperatures in the Arctic begin to increase, however, more and more solar radiation is absorbed by the Arctic Ocean (especially in the summer, when the ice is at its smallest extent). Bodies of water reflect the least amount of insolation of any type of surface, and year-by-year, more of the sun’s energy becomes trapped and accumulated in the Ocean. Soon enough, a dangerous positive feedback loop is initiated, and as more sea ice is melted, the low albedo of the dark ocean left in its place in turn contributes to warmer waters and more ice-free seawater.

According to the lead study on this process of amplified warming in the Arctic, remarkably, just over half of summer sea ice cover since 1980 has been lost.12 Upon taking into account the thickness of the ice, and multiplying it by the extent to which it has melted, we get the volume: which is about 80% less than it was in 1980.13 What little ice is left is described as very broken, rotten and slushy. Moreover, polar scientists construe the ice as being very weak, 11 Mike Lynch, Minnesota Weatherwatch (Minneapolis: Voyageur Press, 2007) 50.12 Jennifer A. Francis and Stephen J. Vavrus, 'Evidence for a wavier jet stream in response to rapid Arctic warming', Environmental Research Letters, No. 10 (2015) 5-7.13 Ibid.

Figure 15: Reconstruction based on satellite imagery of the polar sea ice cap extent, showing just how much the cryosphere has diminished in a little over thirty years.

vulnerable and easily broken up by anomalies in the winds and ocean currents.

Arctic Amplification and the Polar Jet

Linking back to the polar jet stream, we know the strength of the jet stream is determined primarily by the magnitude of the meridional (north-south) temperature gradient between the cold polar air and relatively warmer subtropical air. The ongoing climatic phenomenon of Arctic Amplification implies a reduction in this temperature gradient, and can be represented in this simplified infographic in Figure 16.

Furthermore, a slower jet stream tends to take a more meandering14 (meridional) path as it encircles the Northern Hemisphere. Large north–south jet-stream waves in a highly meandering flow, since they have thousands of miles extra to travel, tend to propagate eastward more slowly. Therefore frontal depressions, anticyclones and other weather systems ought to make slower progress towards the UK and Europe as the effects of Arctic Amplification take hold. In addition to this, polar jet streams that are progressing eastward more slowly carry the supplementary risk of more persistent weather patterns15 that can hang over a location for days or even 14 David W. J. Thompson and John M. Wallace, 'Regional Climate Impacts of the Northern Hemisphere Annular Mode' Science, No. 293 (August 2001) 85-89.15 James A. Screen and Ian Simmonds, 'Amplified mid-latitude planetary waves favour particular regional weather extremes', Nature Climate Change, No. 4 (2014) 704.

Figure 16: A representation of the linkage between Arctic Amplification and the new, reduced meridional temperature gradient (shown in yellow) that drives the polar jet.

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weeks, with the potential to cause a variety of extreme events. These conditions that future jet streams could bring could include unseasonably cold, wet, hot or dry weather lasting for weeks at a time that can be just as destructive as storms: their effects on biodiversity can be disastrous, leading variously to reduced crop yields, crop failure, loss of biodiversity and wildfires, to name but a few effects.

Figure 17 reaffirms the connection between the loss of polar ice (and accompanied warming of the Arctic region) and the falling jet stream speeds due to the reduced meridional temperature gradient. Published by Dr. Jennifer Francis, the world leading authority on jet stream changes in response to rapid Arctic warming, in a thorough, peer-reviewed piece of research, one might expect the debate to end there. Notwithstanding her publications, alternative interpretations and predictions do exist, and uncertainties remain as to the accuracy of the data different scientists cite due to the small number of years data has been gathered on polar jet stream winds, prompting intense debate in scientific circles.

Alternative Interpretations

Most people when interviewed agree that AGW is causing the polar regions to be significantly altered, causing a new state of normal when it comes to the weather they experience. When 1500 New Hampshire residents were asked the question:

Zonal wind at 500 hectopascals/millibars(Jet stream altitude)

Dashed line represents sea ice extent for comparison.

Figure 17: Graph depicting how the drop in high-altitude winds in autumn over the past 30 years (solid line) has closely tracked the decline in Arctic sea ice (dashed line).

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If the Arctic region becomes warmer in the future, do you think that will have major effects, minor effects or no effects on the weather where you live?

Sixty percent16 responded saying arctic warming will have major effects on their weather, with a further twenty-nine percent suggesting this would have minor effects. Despite public sentiment broadly mirroring the scientific consensus that there are unprecedented and significant changes occurring in the polar regions, the mechanisms by which these changes are influencing the jet stream are still highly disputed.

Study by Reading University

Jet streams often make the news when our daily lives become inconvenienced, for instance when there is an unusual period of weather or when there is speculation that our flights might last longer. As such, a February 2016 BBC News article brought public attention towards a Reading University study, which essentially found through complicated computer modelling that a “doubling of atmospheric CO2”17 will increase the speed of the jet stream, thus adding an hour or so to flight times between the UK and the USA, requiring aircraft to carry and burn more fuel thus causing a significant rise in air fares.

The study has been dismissed by many scientists, firstly since it is hard to foresee a future where atmospheric CO2 levels double to 800ppm beyond their already record levels with recent tough Paris climate change legislation now in place.

Furthermore, CO2 emissions changing the chemical make-up of air is unlikely to have a link with influencing the physics behind the temperature gradient which drives the polar jet stream. Reading’s findings clearly contradict the main tenant of arctic amplification.

Moreover, the study also ignores the fact that even if they are correct, and future polar jet streams are faster, the only foreseeable effect of this will be hastier transatlantic crossings in a westerly direction, since these aircraft can gain a 16 Lawrence C. Hamilton and Mary Lemcke-Stampone, ‘Arctic warming and your weather: public belief in the connection.’ International Journal of Climatology, 34 (2014) 1723-1728.17 Paul D. Williams, 'Transatlantic flight times and climate change', Environmental Research Letters, Vol. 11, No. 2 (2016) 4.

Figure 18: The University of Reading scientists believe the changes will increase carbon emissions and fuel consumption and potentially raise ticket prices.

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larger speed advantage. Meanwhile, eastbound flights will be largely unaffected since the pre-arranged tracks they take deliberately avoid conflicting with the headwinds of the polar jet stream at any point.

Concluding Remarks

This investigation is not intended to provide the end of the debate, nor is it the only valid interpretation of the evidence. Specific observations of the jet stream have only been possible in the last thirty years or so due to a lack of technology, and climatic observations require several decades or so to definitively distinguish natural atmospheric variability from climate trends.

However, what we can be certain about is the rapid diminishment of the cryosphere due to a positive feedback loop, where polar ice melts, exposing dark Arctic Ocean to sunlight, which in turn melts more sea ice at an alarming rate. There is much evidence to suggest that this melting is linked with jet stream speeds in the upper atmosphere, though it would be negligent not to be cautious when saying that this trend is true, and that it will surely reduce the meridional pressure gradient and weaken the polar jet stream. It might be useful to take the approach of researchers Barnes and Screen when considering the issue. They pose my question in three parts: “can”, “has” and “will” arctic warming influence the polar jet stream? Most scientists would probably agree that yes, there is great potential for arctic amplification and its associated polar warmth to slow and contort the jet stream, and plenty of studies have shown this. With regards to “has” and “will” it, a more sensible approach would be to answer yes conservatively. There is some evidence to support the claim that the jet stream has been fundamentally changed in nature since AGW kicked in, and many believe the jet stream will have a “modulating” role to play on our weather in future. However depending on the scientific data one considers, there is an element of confliction, since this is a relatively recent phenomenon, involving a short observational record, with no clear answers yet.

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With regards to the primary human use of the polar jet stream, which is for commercial aviation, a future jet stream that is slower (not taking into account whether it meanders more in a meridional direction) will only have an effect on flights that utilise the jet, flying from West to East across the Atlantic for instance, as these planes will receive less of a speed advantage. Aircraft flying in the opposite direction, as shown by Figure 6, tend to take an alternative path of least resistance (typically on the equatorial rather than polar side of the Atlantic) anyway and would be largely unaffected by jet streams.

Terminology

GlossaryPolar jet stream: A narrow ribbon of air that encircles the globe at an altitude

of around 11 km, sometimes reaching speeds of up to 400 kph (250 mph) that traverses the lower layers of the atmosphere. The jet is created by the convergence of cold air masses descending from the Arctic and rising warm air from the tropics. Deep troughs and steep ridges emerge as the denser cold air sinks and deflects warm air regions north, giving the jet stream its wavy appearance. This pattern propagates across the mid-latitudes of North America, Europe and Asia, as pockets of cold air sporadically creep down from the Arctic—creating contrasting waves and flows that accelerate eastward due to the Earth's rotation.

Mauna Loa: An observatory famed as the world's oldest continuous CO2 monitoring station, and the world's primary benchmark site for measurement of the gas. It is located on the side of a 4000 metre high shield volcano of the same name, well above local human-generated influences and far away from any continent. 

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Geostrophic wind: A theoretical wind, occurring when the pressure gradient force (determined by the difference in high and low pressure/how close the isobars are) equals the opposing Coriolis force (assuming straight/nearly straight isobars; when the isobars are strongly curved, the effect of the centrifugal force should be added).

Zonal: A term used to describe directions on a globe, meaning ‘along a line of latitude’ or ‘in the west-east direction’.

Meridional: A direction ‘along a meridian’ or ‘in the north–south direction’.

AcronymsAA – Arctic Amplification.

AGW – Anthropogenic Global Warming.

GHG – Greenhouse gas.

NASA – National Aeronautics and Space Administration.

NOAA – National Oceanic and Atmospheric Administration.

UNFCCC – United Nations Framework Convention on Climate Change.

WMO – World Meteorological Organisation.

Image Credits

Figure Source1 NASA's Goddard Space Flight Center2 Encyclopedia Britannica3 National Oceanic and Atmospheric Administration

4 John Mason

5 National Oceanic and Atmospheric Administration

6 John Grimwade

7 Wikimedia Commons

8 Lidija Grozdanic

9 National Oceanic and Atmospheric Administration

10 Tom Anderson (Candidate 4209)

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11 Scripps Institution of Oceanography

12 U.N. Intergovernmental Panel on Climate Change

13 NASA Goddard Institute for Space Studies

14 Jennifer Francis

15 University of Illinois

16 Tom Anderson (Candidate 4209)

17 Jennifer Francis

18 Tom Anderson (Candidate 4209)

Bibliography

Archer, Cristina L. and Ken Caldeira. 'Global Assessment of High-Altitude Wind Power', Energies (2009).

Flohn, Hermann. Arbeiten zur allgemeinen Klimatologie. Darmstadt: Scientific Buchgesellschaft, 1971.

Francis, Jennifer A. and Stephen J. Vavrus. 'Evidence for a wavier jet stream in response to rapid Arctic warming', Environmental Research Letters, No. 10 (2015)

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Hamilton, Lawrence C. and Mary Lemcke-Stampone. ‘Arctic warming and your weather: public belief in the connection.’ International Journal of Climatology, 34 (2014)

Lynch, Mike. Minnesota Weatherwatch (Minneapolis: Voyageur Press, 2007).

McPhee, John. Balloons of War. New York: The New Yorker, 1996.

National Weather Service. 'Layers of the Atmosphere' <http://goo.gl/i4l7aK>, 14 December 2007.

NOAA National Centers for Environmental Information. State of the Climate: Global Analysis for Annual 2015, <https://goo.gl/oOuHSW>, January 2016.

Oliver, John E. Encyclopaedia of World Climatology (Berlin: Springer Science+Business Media, 2008).

Screen, James A. and Ian Simmonds. 'Amplified mid-latitude planetary waves favour particular regional weather extremes', Nature Climate Change, No. 4 (2014).

Scripps Institution of Oceanography. The Early Keeling Curve, <http://goo.gl/Sj709H> 25 February 2016.

Thompson, David W. J. and John M. Wallace. 'Regional Climate Impacts of the Northern Hemisphere Annular Mode' Science, No. 293 (August 2001).

United Nations Intergovernmental Panel on Climate Change. Fifth Assessment Report (Geneva: 2014).

Williams, Paul D. 'Transatlantic flight times and climate change', Environmental Research Letters, Vol. 11, No. 2 (2016).

World Meteorological Organisation. 'State of the Climate: Record Heat and Weather Extremes' <http://goo.gl/32yhVc>, 21 March 2016.

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