Download CO 2 emissions per country from fossil fuel use and cement production

Climate Change—Lecture 1
The Science of Climate Change
Major Sources
•
Congressional Budget Office (2003), “The Economics of Climate Change: A Primer”
(http://www.cbo.gov/ftpdocs/41xx/doc4171/04-25-ClimateChange.pdf)
•
IPCC (2007), “Climate Change 2007: Synthesis Report. Summary for Policymakers”
(http://www.ipcc.ch/pdf/assessment-report/ar4/wg3/ar4-wg3-spm.pdf)
The Intergovernmental Panel on Climate Change (IPCC) is the leading
international body for the assessment of climate change. It was established by
the United Nations Environment Programme (UNEP) and the World
Meteorological Organization (WMO) in 1988 to provide the world with a clear
scientific view on the current state of knowledge in climate change and its
potential environmental and socio-economic impacts.
1
Different definitions of climate change
• IPCC (International Panel on Climate Change):
change in climate over time, whether due to
natural variability or as a result of human activity.
• UNFCCC (United Nations Framework Convention
on Climate Change): change of climate that is
attributed directly or indirectly to human activity
that alters the composition of the global
atmosphere and that is in addition to natural
variability.
2
• Climate change refers to a major alteration in a climate
measure such as temperature, wind, and precipitation
that is prolonged, i.e., lasting decades or longer
• Global warming: sunlight hits earth’s surface, radiates
back into atmosphere, where its absorption by GHGs
heats atmosphere and warms earth’s surface;
somewhat like a greenhouse that allows sunlight
through the glass but prevents the heated air from
escaping back outside, thus “greenhouse effect”
ECO324-Ch13
3
Energy budget without greenhouse effect (Moon)
Numbers in W/m2
(Watts per square meter)
Source: IPCC (2001)
4
Atmospheric energy budget with greenhouse effect
(Earth)
5
6
Natural greenhouse effect
• The atmosphere contains several trace gases which absorb and emit
infrared radiation. These so-called greenhouse gases absorb infrared
radiation, emitted by the Earth’s surface, the atmosphere and clouds,
except in a transparent part of the spectrum called the “atmospheric
window”. They emit in turn infrared radiation in all directions including
downward to the Earth’s surface. Thus greenhouse gases trap heat
within the atmosphere. This mechanism is called the natural
greenhouse effect. The net result is an upward transfer of infrared
radiation from warmer levels near the Earth’s surface to colder levels at
higher altitudes. The infrared radiation is effectively radiated back into
space from an altitude with a temperature of, on average, –19°C, in
balance with the incoming radiation, whereas the Earth’s surface is
kept at a much higher temperature of on average 14°C. This effective
emission temperature of –19°C corresponds in mid-latitudes with a
height of approximately 5 km. Note that it is essential for the
greenhouse effect that the temperature of the lower atmosphere is
not constant but decreases with height.
7
Enhanced greenhouse effect
• An increase in the concentration of greenhouse gases
leads to an increased infrared opacity of the atmosphere,
and therefore leads an effective radiation into space from
a higher altitude at a lower temperature. This causes a
radiative forcing that leads to an enhancement of the
greenhouse effect, the so-called enhanced greenhouse
effect.
• An easier definition: an increase in the natural process of
the greenhouse effect, brought about by human activities,
whereby greenhouse gases such as carbon dioxide,
methane, chlorofluorocarbons and nitrous oxide are being
released into the atmosphere at a far greater rate than
would occur through natural processes and thus their
concentrations are increasing. Also called anthropogenic
greenhouse effect.
8
• Natural greenhouse effect makes sure earth
has nice temperature: on average 14°C instead
of –19°C
• Enhanced greenhouse effect is anthropogenic:
human-caused emissions of GHGs tips natural
system out of equilibrium
9
Main greenhouse gases
Greenhouse
Gas
Carbon Dioxide
Chemical Formula
Anthropogenic
Sources
CO2
Fossil-fuel
combustion, Landuse conversion,
Cement Production
Methane
CH4
Nitrous Oxide
N2O
Tropospheric Ozone
O3
CFC-12
CCL2F2
HCFC-22
CCl2F2
Fossil fuels,
Rice paddies,
Waste dumps
Fertilizer,
Industrial
processes,
Combustion
Fossil fuel
combustion,
Industrial
emissions,
Chemical solvents
Liquid coolants,
Foams
Refrigerants
Sulfur Hexaflouride
SF6
Dielectric fluid
Atmospheric Lifetime GWP (100 Year Time
(years)
Horizon)
~100
1
12
25
114
298
hours-days
N.A.
100
10,900
12
1,810
3,200
22,800
10
Pre-1750 Tropospheric
Concentration
(parts per billion by
volume)
Current Tropospheric
Concentration
(parts per billion by
volume)
Carbon Dioxide
280,000
388,500
Methane
700
1,870 / 1,748
Nitrous Oxide
270
323 / 322
Tropospheric Ozone
25
34
CFC-12
0
.534 / .532
HCFC-22
0
.218 / .1941
Sulfur Hexaflouride
0
.00712 /.00673
11
• The previous two tables present characteristics of
major greenhouse gases. The Global Warming Potential
(GWP) indicates the warming effect of a greenhouse
gas, while the atmospheric lifetime expresses the total
effect of a specific greenhouse gas after taking into
account global sink availability. The lifetime indicates
how long the gas remains in the atmosphere. The vast
majority of emissions are carbon dioxide followed by
methane and nitrous oxide. Lesser amounts of CFC-12,
HCFC-22, Perflouroethane and Sulfur Hexaflouride are
also emitted and their contribution to global warming
is magnified by their high GWP, although there total
contribution is still small compared to the other gasses.
12
Measures of climate dynamics
• Global warming potential (GWP)—based on heat-absorbing
ability of each gas relative to that of carbon dioxide;
calculated over a specific time interval, commonly 20, 100
or 500 years; the 20 year GWP of methane is 72, which
means that if the same mass of methane and carbon
dioxide were introduced into the atmosphere, one unit of
methane has 72 times the capacity for heat absorptions as
one unit of carbon dioxide over the next 20 years
• Radiative forcing (RF)—is a measure of the influence that a
factor has in altering the balance of incoming and outgoing
energy in the Earth-atmosphere system and is an index of
the importance of the factor as a potential climate change
mechanism. Positive forcing tends to warm the surface
while negative forcing tends to cool it. Expressed in watts
13
per square meter (W/m2).
• The concept of RF is useful because a linear relationship has
been determined between the change in global mean
surface temperature (ΔT) and the change in RF since 1750
(ΔRF):
ΔT=λ ΔRF
• The temperature increase caused by a doubling of CO2
concentration with respect to pre-industrial 1750 is called
“climate sensitivity parameter”; the IPCC (2007) estimates it
to be in the range of [2°C, 4.5°C] with a best estimate of 3°C
= 5.4°F
• If climate sensitivity is ΔT ≈ 3°C and the forcing caused by a
doubling of CO2 is ΔRF ≈ 3.7 W/m2
we find that λ = ΔT/ΔRF ≈ 0.8°C / (W/m2)
14
Global CO2 emissions up 3% in 2011
Anne-Françoise PELE ,7/26/2012
http://www.eetimes.com/electronics-news/4391238/Global-CO2-emissions-up-3--in-2011
• PARIS—After a 1% decline in 2009 and an
unprecedented 5% surge in 2010, global
emissions of carbon dioxide increased by 3% in
2011, to 34 billion tons, according to the annual
report “Trends in global CO2 emissions” by the
European Commission's Joint Research Center
(JRC) and the Netherlands Environmental
Assessment Agency (PBL).
15
• The 3% increase in global CO2 emissions in 2011
is above the past decade's average annual
increase of 2.7%. The top emitters contributing to
the 34 billion tones of CO2 emitted globally in
2011 are: China (29%), the United States (16%),
the European Union (11%), India (6%), the
Russian Federation (5%) and Japan (4%).
16
CO2 emissions per
country from fossil
fuel use and cement
production
17
CO2 emissions per
country from fossil
fuel use and cement
production
18
Andrew LeDnne, November 1, 2011
https://sge.lclark.edu/2011/11/01/comparing-per-capita-gdp-vs-per-capita-co2-emissions/
19
Impact of current emissions
20
• After CO2 emissions are reduced and atmospheric
concentrations stabilize, surface air temperature
continues to rise slowly for a century or more. Thermal
expansion of the ocean continues long after CO2
emissions have been reduced, and melting of ice
sheets continues to contribute to sea-level rise for
many centuries. This figure is a generic illustration for
stabilization at any level between 450 and 1,000 ppm,
and therefore has no units on the response axis.
Responses to stabilization trajectories in this range
show broadly similar time courses, but the impacts
become progressively larger at higher concentrations
of CO2.
21
Climate change indicators (I)
We do observe
that warmer
climate was
usually
associated
with higher
atmospheric
concentrations
of greenhouse
gases;
methane has
similar pattern.
22
• How do they actually get temperatures hundreds of
thousands years back ?!
• Drilling deep, deep holes into glaciers and polar ice and
analyzing tiny air bubbles for isotopes whose
composition reflects the temperature as it prevailed on
the surface when they were trapped.
• These air bubbles also indicate the CO2 concentration at
that time!
23
• The figure shows the combined land-surface air and sea surface
temperatures (degrees Centigrade) from 1861 to 1998, relative to the
average temperature between 1961 and 1990.
• The mean global surface temperature has increased by about 0.3 to
0.6°C since the late 19th century and by about 0.2 to 0.3°C over the last
40 years, which is the period with most reliable data. Recent years have
been among the warmest since 1860 - the period for which
instrumental records are available.
24
Climate change indicators (II)
Source: IPCC (2007)
“Warming of the
climate system is
unequivocal, as is
now evident from
observations of
increases in global
average air and
ocean
temperatures,
widespread melting
of snow and ice,
and rising global
average sea level”
25
Causes of climate change
• “Global GHG emissions due to human activities have grown since
pre-industrial times, with an increase of 70% between 1970 and
2004.”
• “Most of the observed increase in global average temperatures
since the mid-20th century is very likely due to the observed
increase in anthropogenic GHG concentrations. It is likely that
there has been significant anthropogenic warming over the past
50 years averaged over each continent (except Antarctica).”
• “The observed widespread warming of the atmosphere and
ocean, together with ice mass loss, support the conclusion that it
is extremely unlikely that global climate change of the past fifty
years can be explained without external forcing, and very likely
that it is not due to known natural causes alone.”
Source: IPCC (2007)
26
Anthropogenic climate change
• “Black carbon”(smoke e.g. from diesel engines) traps all
radiation passing by, thus strongly heating the lower
atmosphere.
• When we heat the earth, snow and ice covers may melt,
decreasing the albedo, increasing the temperature.
• Slightly more than half of anthropogenic greenhouse gas
emissions is CO2 from fuels combustion (oil, gas, and
coal) and cement production.
• Substantial emissions come from land use change
(cutting down forests).
• Methane is a very powerful greenhouse gas (about 70
times as powerful as CO2), but depreciates faster. It’s
effective life-time potential is about 20 times as high as
for CO2. Rice fields and cattle are famous sources of
methane emissions.
27