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Himalaya climate change

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Saving the planet: Emissions scenarios, stabilization issues, and ... STAB. BASE. Wedges already built into no-policy baseline: neglected by Pacala and Socolow. ... – PowerPoint PPT presentation

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Title: Himalaya climate change


1
Saving the planet Emissions scenarios,
stabilization issues, and uncertaintiesNCAR
Summer Colloquium on Climate and HealthNCAR,
Boulder, CO.19 July, 2006
Tom Wigley, National Center for Atmospheric
Research, Boulder, CO.
2
Introduction
  • The climate change problem is essentially an
    energy problem that requires moving away from the
    use of fossil fuels as our primary energy source.
  • This will almost certainly require the
    development of new carbon-free (or carbon
    neutral) energy technologies.
  • To determine the magnitude of this technological
    challenge we need to know what will happen in the
    absence of policies to limit climate change, and
    what a safe level may be for future climate
    change.

3
Summary
  • Climate changes observed over the 20th century
  • Future climate change the no-policy case
  • Future climate change stabilization policies
  • Future changes in energy production
  • Carbon-free energy requirements for stabilization
  • Technology options
  • The wedge concept
  • Geoengineering

4
  • PAST CLIMATE CHANGE

5
Observed temperature changes
5 of the 6 warmest years have occurred this
decade. 1998 was unusually warm due to a large
El Niño that occurred in 1997/8.
6
  • FUTURE CLIMATE CHANGE
  • (in the absence of policies to reduce climate
    change)

7
The SRES no-policy emissions scenarios
  • The Intergovernmental Panel on Climate Change
    (IPCC) has sponsored production of a set of 40
    no-climate-policy emissions scenarios for GHGs,
    sulfur dioxide, and other gases
  • These scenarios are based on a range of
    assumptions for future population and economic
    growth, technological change, etc., grouped into
    four families or storylines (A1, A2, B1, B2)
  • The scenarios are published in a Special Report
    on Emissions Scenarios hence the acronym SRES
  • Six of these scenarios have been used for
    detailed climate calculations (A1B, A1FI, A1T,
    A2, B1, B2)

Special Report on Emissions Scenarios, Eds. N.
Nakicenovic R. Swart, C.U.P. (2000)
8
SRES scenarios Family characteristics
9
SRES population projections
10
Economic growth per capita GDP
11
SRES fossil CO2 emissions
Remember, the B scenarios focus on sustainable
development.
12
SRES CO2 concentration projections
NOTE Increasing CO2 is not only a climate
problem. Increasing CO2 makes the ocean more
acidic, eventually making it impossible for
carbonate shell-producing animals to produce
shells. Extinction of these animals will upset
the ocean food chain and could lead to much
larger scale extinctions
13
  • RELATIVE IMPORTANCE OF CO2

14
20002100 radiative forcing breakdown
NOTE Dominant role of CO2
15
Global-mean temperature projections
16
Future warming compared with the past
17
  • THE POLICY CASE CONCENTRATION STABILIZATION

18
Article 2 of the UNFCCC
  • Article 2 provides the basis for climate policy.
    Its objective is
  • stabilization of greenhouse gas concentrations
    .. at a level that would prevent dangerous
    anthropogenic interference with the climate
    system .. within a time-frame sufficient to
    allow ecosystems to adapt naturally to climate
    change, to ensure that food production is not
    threatened and to enable economic development to
    proceed in a sustainable manner.

19
CO2 stabilization pathways
  • POINTS TO NOTE
  • Stabilization of CO2 concentration requires,
    eventually, very large reductions in CO2
    emissions. The arrow shows the reduction in 2050
    if we wish to stabilize at 450ppm
  • Since most CO2 comes from energy usage,
    stabilizing CO2 requires that we need to obtain a
    large fraction of future energy from carbon-free
    sources.
  • A key issue is, what should the stabilization
    level be in order to avoid dangerous
    interference with the climate system?

20
  • FUTURE ENERGY PRODUCTION IN THE NO-CLIMATE POLICY
    CASE (SRES SCENARIOS)

21
PRIMARY ENERGY BREAKDOWN
  • NOTE Even in the absence of climate policies,
    large increases are projected for carbon-free
    energy

22
  • HOW MUCH ADDITIONAL CARBON-FREE ENERGY IS
    REQUIRED FOR CO2 CONCENTRATION STABILIZATION?
  • The answer depends on the assumed no-policy
    baseline scenario (35 possibilities in the SRES
    scenario set) and on the chosen concentration
    stabilization level (also a wide range of
    possibilities).
  • This implies a wide uncertainty range.

23
Carbon-free energy requirements
EXAMPLE The blue lines show how much carbon-free
energy is already built into the baseline
scenarios In the B1 case, the vertical arrow
shows the additional carbon-free energy required
to move from the no-policy B1 scenario to the
WRE450 stabilization pathway. Note that B1 is a
very optimistic scenario other baseline
scenarios require much greater amounts of
additional carbon-free energy.
24
Extra carbon-free energy needed in 2050 (TW)
Current carbon-free energy ? 2TW
25
Extra carbon-free energy needed in 2050 (TW)
Current carbon-free energy ? 2TW
  • POINTS TO NOTE
  • (1) The baseline scenarios show large increases
    in carbon-free energy even in the absence of
    climate policies. This limits the options for
    additional carbon-free energy.
  • (2) The large amounts of carbon-free energy
    required for stabilization levels of 450ppm or
    less will almost certainly require the
    development of new technologies.

26
  • TECHNOLOGY OPTIONS

27
CO2 emissions reduction opportunities
Includes direct capture from the atmosphere
28
  • TECHNOLOGY WEDGES

29
Pacala Socolow wedges
A wedge is a single existing technology that
can be scaled up to reduce CO2 emissions by
1GyC/yr in 2055 or reduce cumulative emissions
over 20052055 by 25GtC.
Pacala and Socolow claim that a 500 ppm
stabilization pathway can be followed, at least
to 2055, using existing technology. This is
incorrect.
S. Pacala R.Socolow Science 305, 968972
(2004)
30
Baseline wedges
The flaw in Pacala and Socolow is that they fail
to account for wedges already built into the
baseline scenario. SRES baselines all contain a
large amount of carbon-free energy growth (red
arrow) that arises spontaneously, in the absence
of climate policy.
31
Wedges required for stabilization(through to
2055)
Wedges already built into no-policy baseline
neglected by Pacala and Socolow.
32
Wedges required for stabilization(through to
2055)
Wedges already built into no-policy baseline
  • POINTS TO NOTE
  • Pacala and Socolow identify 15 existing
    technology wedges, each of which could be scaled
    up to reduce emissions in 2055 by 1GtC/yr
  • However, the total number of wedges required to
    follow WRE450 to 2055 is between 21 and 49
  • We therefore need to develop new carbon-free
    energy technologies probably requiring a
    massive investment in research, demonstration and
    dissemination.

33
  • OTHER TECHNOLOGY OPTIONS GEOENGINEERING

34
Geoengineering (1)
  • Reducing CO2 emissions (mitigation -- i.e.,
    moving from the use of fossil fuels as our
    primary energy source to the use of carbon-free
    energy technologies) is the standard solution
    to the climate problem. Geoengineering is an
    alternative approach.
  • Geoengineering aims to offset CO2-induced climate
    change by deliberately altering the climate
    system.
  • The earliest suggestion was to inject
    aerosol-producing substances into the
    stratosphere to provide a cooling shield i.e.,
    to produce a human volcano.

35
Geoengineering (2)
  • The problem with geoengineering as a single
    solution is that our use of fossil fuels creates
    two problems, climate change and increasing CO2.
  • Increasing CO2 makes the oceans more acidic and
    could lead to the extinction of all carbonate
    shell producing animals in the ocean.
  • As these animals are at the bottom of the food
    chain, their extinction could lead to the
    extinction of all life in the ocean.
  • Geoengineering cannot replace mitigation (i.e.,
    the reduction in fossil fuel use), but it may
    make mitigation easier.

36
Effect of multiple volcanic eruptions
MULTIPLE PINATUBOS As an analogy, we consider a
case where we know the effects of a known
injection of SO2 into the stratosphere, the
eruption of Mt Pinatubo (June, 1991) Pinatubo
released 10TgS of SO2 into the stratosphere. This
is 15-20 of the current amount of SO2 that we
release each year into the troposphere. The
eruption cooled the planet by 0.5 0.7oC.
37
Alternative geoengineering scenarios
Scenarios like these produce immediate cooling,
offsetting the short-term effects of increasing
CO2. This means that, with geoengineering, we
would not have to reduce CO2 concentrations or
emissions so rapidly. This gives us more time to
develop alternative, cost-effective carbon-free
energy sources.
-3W/m2 is equivalent to Pinatubo every two years
(5TgS/yr)
38
Concentrations and implied emissions
Overshoot is the case that includes
geoengineering. Note how this gives us much more
time (around 20 years) to begin the required
rapid reduction in CO2 emissions i.e., more
time to phase out existing energy systems and
develop alternative technologies.
39
Geoengineering effects on climate
The important comparison here is between WRE450
(mitigation alone) and LOW, MID or HIGH GEO
(geoengineering combined with slower mitigation,
but with the same CO2 stabilization level).
40
CONCLUSIONS
  • Global warming is primarily an energy problem.





  • The problem, however, is two-fold involving
    both climate change and the effects of increasing
    CO2 on ocean acidity.
  • Solving both problems requires satisfying very
    large future energy demands with, primarily,
    carbon-free energy sources.
  • Projected carbon-free energy requirements are
    extremely large. They cannot be satisfied with
    current technology.
  • Large investments are required to develop these
    new technologies.
  • Moderate intervention using geoengineering could
    give us time to develop and implement these new
    technologies.

41
Thankyou
.
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