Commercial Aviation Emissions and Global Surface Temperatures

byJerome Lawrence

McNair Scholars ProgramEmbry-Riddle Aeronautical University

Purpose

The purpose of this research is to analyze the amounts and effects of various

emissions from commercial aviation, determine which gases contribute to warming or cooling the atmosphere,

and estimate the average net radiative forcing (W/m2) forecast for 2050.

Introduction

• Aviation: Very important role in the diversity and prosperity of a country’s economy

• Presently: Air transport industry provides 28 million direct, indirect and induced jobs worldwide

• Compared with total passenger kilometers flown in 1995, an estimated increase of between 450% to 820% by 2050

• This growth will result in 14 billion to 23 billion passenger kilometers flown annually by mid-century

Radiative Forcing

• Radiative forcing (RF) is a concept used for quantitative comparisons of the strength of different human and natural agents in causing climate change.

• Each agent has a different RF value.

• CO2 concentrations in 2005 had an RF of 1.66 [±0.17] Wm-2

: a 20% increase from 1995.

Components of the Climate Change Process

(IPCC, 2007)

It is hypothesized that the projected increase in air travel (pass. km)

will significantly increase thepositive radiative forcing (W/m2) from

commercial aviation emissions

Hypothesis

Combustion Process

• CO2, NOx, SOx, H2O and soot are all by products

of combustion

• For every gallon of fuel burned,

21 lbs of CO2 is emitted

• Reducing fuel use reduces the amount of

CO2 emitted

(GAO, 2009)

Air Quality and Aircraft Emissions

Volatile Organic Compounds

•VOCs: Umbrella term for numerous compounds that become a gas at normal pressures and temperatures

•Extended exposure to some VOCs results in: eye and respiratory tract irritation,

visual problems, headaches, dizziness, and memory impairment

Air Quality and Aircraft Emissions

Unburned hydrocarbons

• During the combustion process, some of these hydrocarbons are not burned completely or not burned at

all and are referred to as Unburned Hydrocarbons • The top of nitrogen oxides and VOCs are

• 1.chemical factories2. oil refineries

3.power stations 4.airports

The Greenhouse Effect

• As the sun’s energy traverses the atmosphere it does not change the temperature of the atmosphere,

but it changes the temperature of the land.

• Earth then reradiates a longer wave of energy that falls in the thermal infrared band of wavelengths of the electromagnetic spectrum.

• These wavelengths are easily

absorbed by greenhouse gases, such as carbon dioxide, water vapor, methane, and ozone

Air Quality and Aircraft Emissions

Nitrogen oxides

• Nitrogen oxides (NOx) include nitrogen dioxide (NO2), nitric oxide (NO), and nitrous oxide (N2O).

•Estimates for specific engine-airframe combinations range from 6 to 40g of NOx per kilogram of fuel burned

• The World Wildlife Federation estimated that NOx emitted from aircraft above 10,000 feet have up to 50 times the warming effect of

NOx emitted at lower levels.

Air Quality and Aircraft Emissions

Particulate matter

•Particulate matter is a subset of the larger group known as aerosols

•Many particulates, such as soot, serve as condensation nuclei for water vapor in the atmosphere and tend to form more high cirrus clouds than would otherwise be

present.

Air Quality and Aircraft Emissions

Carbon dioxide•Preindustrial levels of CO2 were 280 ppm and the global average for 2011

was 392 ppm.

•Nearly 20% of the greenhouse gas emissions worldwide are from

transportation.

•The CO2 emitted by air transport is at least 0.23 billion tonnes of carbon

dioxide (GtC) per year.

• By 2050, aviation is expected to add 1.45 GtC to the atmosphere annually.

Air Quality and Aircraft Emissions

• The radiative forcing of CO2 is positive, that is, it contributes to the warming of the earth.

• In 1992, aviation contributed 2.5% of the total anthropogenic greenhouse gas emissions. That amount has increased to over 3.5%

• CO2 is a potent greenhouse gas partly because of its residence time which is approximately 100 years.

Air Quality and Aircraft Emissions

Contrails

•Contrails, or condensation trails, which are formed from water vapor emitted from aircraft that freezes

into clouds at high altitudes, also affect global temperatures

•.

(Eden, n.d)

• Databases, such as Proquest, Google Scholarly, and publications from the Federal Aviation Administration (FAA) were reviewed.

• The researcher used descriptive statistics to depict the data. Data were also collected from the Intergovernmental Panel on Climate Change (IPCC).

• The data, when appropriate, were imported into Microsoft Excel and Microsoft Word to create graphics with trend lines to show the tendency of changes. Graphic data allowed for the exploration of decadal changes in CO2 concentrations.

Method

(IPCC, 2007)

• Global radiative forcing (RF) estimates and ranges for anthropogenic carbon dioxide, methane (CH4),

nitrous oxide (N2O), contrails and other important agents

X-axis shows Time: 10,000 YBP to Present 2nd Y-axis: Radiative Forcing

(IPCC, 2007)

• Carbon Dioxide (CO2)

• Methane (CH4)

• Nitrous Oxide (N2O)

Changes in Global Temperatures,

Sea Level, and Snow Cover: 1850-2005

• As GHGs prevent some of the heat reradiated by Earth from leaving

the atmosphere, global average

temperatures rise, and snow cover declines

• Excessive CO2 and other GHGs, therefore, have a

domino effect on the environment

(GAO, 2009)

Sources of CO2

(GAO, 2009)

Relative Warming:GHGs from Aviation Emissions

(GAO, 2009)

Growth in Aviation:1978-2008

• The amount of GHG emission caused by aviation could increase from 3.5% at present to a high of

15% by the year 2050

• CO2 emissions from aviation will range from 843-5,317 million tons per year by the year 2050,

a significant increase from 514 million tons in 1992• Currently there are no laws on emissions at high altitudes partly because there is no strong lobby to

reduce those emissions

Reducing Emissions

• NextGen would reduce aircraft emissions by 10-15% by the year 2025 by using alternate fuels,

newer equipment and enhanced operational procedures

• If the industry continues to grow at its present rate there would be an estimated 3% increase in emissions

for every 5% increase in traffic

• The IPCC has forecast that by the year 2050, • fuels would be 40-50% more efficient

• and there will be a decrease of NOx emissions • of 30-50% per aircraft

Reducing Emissions

Conclusions

• An increase in sea level is likely, longer and more intense natural events will occur.

• Sulfates, PM, UHCs, contrails, cirrus, clouds, and GHGs all contribute to atmospheric warming.

• The alternate hypothesis is accepted:HA: The projected increase in air travel (pass. km) will significantly increase positive radiative forcing (W/m2)

from commercial aviation emissions.

Recommendations

• The development of international laws for regulating emissions

• The EPA could implement more stringent laws and regulations to reduce emissions

• The average operating cost for a Boeing 737-400 is $2,865.00 per hour. If alternative fuel sources are used

this cost will be reduced by 10%• Emissions trading

• Blended Wing Body (BWB) aircraft is another type of design which is still in development.

• Historically and currently, the fossil fuel industry is the only industry that has not

had to pay for dumping its waste

(CO2 into the air)

Is it time for a change?