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Is Global Warming Happening Now

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... Global Warming Happening Now? Background. Big 3 Bits of Evidence. Other ... scientists have big egos and often DO NOT get along. A Nobel Prize is A Nobel Prize ... – PowerPoint PPT presentation

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Title: Is Global Warming Happening Now


1
Is Global Warming Happening Now?
  • Background
  • Big 3 Bits of Evidence
  • Other Evidence
  • Temperature Drivers
  • The IPCC Report

2
The System
3
Terrestrial Atmospheres
Earth Venus Mars
Tequilibrium 263 K 238 K
222 K Tsurface 288
K 733 K 215 K Psurface
1.013 bar 92 bar 6 millibar
at least 1
at least 50 ppm
Planetary Sciences De Pater Lissauer 2001
4
Temp, Sea Level, Snow Cover
Temperature (surface not stratosphere) 11
of last 12 years (1995-2006) rank among the
12 warmest years in record of global
surface temperature since 1850 100 yr
(1906-2005) 0.74 0.18 C/century 50 yr
(1956-2005) 1.3 0.3 C/century Sea Level
(tide gauges blue, satellites red) 1961-2003
1.8 0.5 mm/yr 1993-2003 3.1 0.7
mm/yr 57 from ocean expansion
28 melting glaciers and ice caps 15
melting polar ice sheets N.
Hemisphere Snow (March-April) 1978-2005
-2.7 0.6 per decade drop in average
Arctic sea ice extent IPCC Fourth Assessment
Report 2007 Synthesis Report, page 31
changes relative to means 1961-1990 curves are
decadal averages shaded regions are uncertainties
5
Global Temperatures
pollution cooling?
6
Continental Temperature Curves
Surface Temperatures 6 out of 7 landmasses
temperatures up 1906-2005 simulations
include blue natural Sun volcanoes red
natural anthropogenic IPCC Fourth
Assessment Report 2007 Synthesis Report, page 40
7
Global Sea Levels
University of Colorado at Boulder website update
of TOPEX/Poseidon Jason satellite data, 2008
8
Arctic Ice Melt
satellite observations since 1979 6 most
recent years 2004-2009 are the lowest 6
since 1979 seasonal thin ice in 2008 was 70
was 40-50 in 1980s/1990s EARTH ALBEDO
CHANGING
30 years ahead of predictions
Stroeve et al. 2007, Geophysical Research
Letters National Center for Atmospheric Research
(NCAR) University of Colorado National Snow and
Ice Data Center (NSIDC), NASA QuikScat and IceSAT
satellites
9
Physical System (H2O) Changes
Significant Changes in Snow, Ice, Frozen
Ground, Hydrology, Coastal Processes
29,000 data series used must end after 1990
(recent) spanning at least 20 years
(meaningful) significant change IN EITHER
DIRECTION - 28,000 data series from Europe
changes consistent with warming
surface temp changes 1970-2004 PCC
Fourth Assessment Report 2007 Synthesis Report,
Figure 1-2
10
Other Evidence
  • - 7 maximum areal extent of seasonally frozen
    ground in N. Hemisphere
  • IPCC Fourth Assessment Report, page 30
  • 90 average N. Hemisphere temps 1950-2000
    higher than during any other 50-year period
    in the last 500 years
  • 66 average N. Hemisphere temps 1950-2000
    higher than during any other
  • 50-year period in the past 1300 years
  • IPCC Fourth Assessment Report, page 30
  • 90 earlier timing of spring events leaf
    unfolding, bird migration, egg-laying
  • 80 earlier greening of vegetation in spring
    since 1980s
  • IPCC Fourth Assessment Report, page 33
  • 80 in ocean, algal range shifts, plankton and
    fish at high latitudes
  • IPCC Fourth Assessment Report, page 33

11
Temperature Drivers
deviations from warming possibly even leading
to cooling volcanic aerosols coolant, but
intermittent pollutants coolant, but
removed via laws sulfates in US/Europe
until 1970s El Nino too small at 0.1 C,
quasi-periodic CO2 as atmospheric
coolant Milankovitch cycles solar
irradiance trends not (yet) observed Antarctic
sea ice no multi-decade trend in either
direction Antarctic continent no multi-decade
trend in temp in either direction no clear
trends small-scale tornadoes, hail, lightning,
dust storms National Center for Atmospheric
Research www.ucar.edu/news/features/climatechange/
faqs.jsp IPCC Fourth Assessment Report, page
33 National Geographic, August 2007
12
CO2 as Coolant
CO2 cools the stratosphere but not the
troposphere atmosphere thins with
altitude CO2 absorption/emission cross sections
change heat exchange processes change occurs
in Venus upper atmosphere and Mars at low
densities (HCN on Titan) record low temps in
stratosphere CO2 is changing climate
Must be careful when discussion WHERE
warming/cooling occurs different environment and
less CO2 at altitude means less total cooling.
13
Milankovitch Cycles
predictable changes in Earths position/orientatio
n relative to the Sun orbital eccentricity is
periodic over 100,000 years high e warm
periods low e ice ages primary driver of
cyclic Earth warming/cooling obliquity of
rotation axis is periodic over 41,000
years more tilt warmer summers more ice
melt less tilt cooler summers ice
ages precession of rotation axis over 23,000
years solstice dates drift land mass in N.
Hemisphere and approach to Sun Definitely
changes Earths temperature, but these are
gradual changes.
14
Solar Irradiance
Sun varies in brightness 11-year sunspot
cycle few sunspots less energy emitted
cooler Earth 1790-1820 Dalton
Minimum 1645-1715 Maunder Minimum the big
one Little Ice Age 1450-1540 Sporer
Minimum 1280-1340 Wolf Minimum 1010-1050
Oort Minimum MM drop (extreme) 0.2 SI temp
drop of 0.5 C many sunspots more energy
emitted warmer Earth 1100-1250 Medieval
Maximum Medieval Warm Period (Europe)
Vikings to Greenland and Canada 11-year cycle in
the temperature record is at 0.1 C long-term Sun
evolution too slow, too steady to be
meaningful Dean, W.E., USGS Publication, Fact
Sheet The Sun and Climate (and references
therein)
15
IPCC Conclusion
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. IPCC Fourth
Assessment Report, page 72
16
IPCC Data Uncertainties
Treatment of uncertainty The IPCC uncertainty
guidance note1 defines a framework for the
treatment of uncertainties across all WGs and in
this Synthesis Report. This framework is broad
because the WGs assess material from different
disciplines and cover a diversity of approaches
to the treatment of uncertainty drawn from the
literature. The nature of data, indicators and
analyses used in the natural sciences is
generally different from that used in assessing
technology development or the social sciences. WG
I focuses on the former, WG III on the latter,
and WG II covers aspects of both. Three different
approaches are used to describe uncertainties
each with a distinct form of language. Choices
among and within these three approaches depend on
both the nature of the information available and
the authors expert judgment of the correctness
and completeness of current scientific
understanding. Where uncertainty is assessed
qualitatively, it is characterised by providing a
relative sense of the amount and quality of
evidence (that is, information from theory,
observations or models indicating whether a
belief or proposition is true or valid) and the
degree of agreement (that is, the level of
concurrence in the literature on a particular
finding). This approach is used by WG III through
a series of self-explanatory terms such as high
agreement, much evidence high agreement, medium
evidence medium agreement, medium evidence etc.
Where uncertainty is assessed more quantitatively
using expert judgement of the correctness of
underlying data, models or analyses, then the
following scale of confidence levels is used to
express the assessed chance of a finding being
correct very high confidence at least 9 out of
10 high confidence about 8 out of 10 medium
confidence about 5 out of 10 low confidence
about 2 out of 10 and very low confidence less
than 1 out of 10. Where uncertainty in specific
outcomes is assessed using expert judgment and
statistical analysis of a body of evidence (e.g.
observations or model results), then the
following likelihood ranges are used to express
the assessed probability of occurrence virtually
certain 99 extremely likely 95 very likely
90 likely 66 more likely than not 50
about as likely as not 33 to 66 unlikely very unlikely exceptionally unlikely combination of confidence and likelihood
assessments and WG I has predominantly used
likelihood assessments. This Synthesis Report
follows the uncertainty assessment of the
underlying WGs. Where synthesised findings are
based on information from more than one WG, the
description of uncertainty used is consistent
with that for the components drawn from the
respective WG reports. Unless otherwise stated,
numerical ranges given in square brackets in this
report indicate 90 uncertainty intervals (i.e.
there is an estimated 5 likelihood that the
value could be above the range given in square
brackets and 5 likelihood that the value could
be below that range). Uncertainty intervals are
not necessarily symmetric around the best
estimate. IPCC Fourth Assessment Report
2007 Synthesis Report
17
Why Respect the IPCC Report?
IPCC awarded 2007 Nobel Peace Prize (shared with
Al Gore) for their efforts to build up and
disseminate greater knowledge about man-made
climate change, and to lay the foundations for
the measures that are needed to counteract such
change 40 members of Core
Writing Team 12 Review Editors
scientists have big egos and often DO NOT get
along A Nobel Prize is A Nobel Prize From the
IPCC response to the Nobel Committee Hundreds
of authors from all regions of the planet have
devoted an incredible amount of time and labour
to writing and reviewing the reports. None of
them has been paid for their time. The IPCC
assessments are based on peer-reviewed scientific
and technical literature Most important is its
ability of carrying out rigorous scientific
assessment, which undergoes the scrutiny of
government representatives and therefore is
accepted by governments.
18
Whats Next?
IPCC is outlining the Fifth Assessment
Report to be finalized in 2014 analysis takes
time, so data a few years behind release Address
uncertainties climate data limited in some
regions (developing countries, poles) extreme
events (drought, cyclones) are rare, require
longer monitoring adaptation in natural systems
can squelch perturbations temp changes at
sub-continent scales affected by land
use/pollution science Id like to see monitor
Venus and Mars temperatures over decades
19
Definitive Proof
20
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