Human Activities

1
CHEMRAWN-XVII/ICCDU-IX Queens U, July 2007
Human Activities and Climate Change Why
Worry?
Henry Hengeveld Emeritus Associate Environment
Canada
2

April 18, 2006 Letter to PM of Canada

• Dear Prime Minister
• As climate science leaders from the academic,
  public and private sectors across Canada. we
  urge you and your government to develop an
  effective national strategy to deal with the many
  important aspects of climate that will affect
  both Canada and the rest of the world in the near
  future
• Signed by 90 Canadian climate science leaders
  from the academic, public and private sectors

3

April 6, 2006 Letter to PM of Canada

• Dear Prime Minister
• .Observational evidence does not support
  today's computer climate models, so there is
  little reason to trust model predictions of the
  future.allocating funds to stopping climate
  change would be irrational
• Signed by 60 accredited experts in
• climate and related scientific disciplines

4
Climate Change Why Worry?

• What causes climate to change?
• - Role of GHGs?
• Has our climate changed? Why?
• How is it likely to change in the future?
• Why worry?
• What can we do to reduce the risks of danger?

5

                                               
         
The atmospheres energy budget is determined by
net heat flow
 
6

                                               
         
Estimating the Magnitude of the Natural
Greenhouse Effect
 
Net Incoming Solar Energy
Outgoing Heat Energy

(S0 (1-A) ?R2)
(4?R2kTe4)
where
S0 is the solar constant A is average albedo, or
reflectivity R is the radius of the earth k is
Boltzmanns constant Te is earths apparent
temperature (seen from space)
Te
equals -19?C
?
However, average global surface T is 14?C
Natural greenhouse effect warms the surface by
33?C
?
7
Primary Contributors to the Natural Greenhouse
Effect
10
25
65
8
GHG concentrations are now unprecedented in at
least the past 650,000 years
9
Other factors have also affected climates over
the past century
10
Net human induced forcing to date between 0.6
and 2.4 W/m2
11
Climate Change Why Worry?
Has our climate changed? Why?
12
Antarctic temperatures were very stable during
the Holocene
Antarctic T trends
13
Composite results of recent paleoclimate studies
agree that past 50 years is unusually warm
14
Global temperatures have rise by .74C during the
past century
15
Changes in temperature are unevenly distributed
Change in annual mean 1955 2005
16
Drought is increasing most places
The most important spatial pattern (top) of the
monthly Palmer Drought Severity Index (PDSI) for
1900 to 2002. The time series (below) accounts
for most of the trend in PDSI.
17
Minimum Arctic ice cover recorded in September is
setting new records
2006
18
Sea-level rise
Reconstructed Tide Gauge
Satellite Altimetry
IPCC(2007)
19
Global costs of natural disasters are rising
rapidly
80B US
20
Global costs of natural disasters are rising
21
West Nile Virus spreads across Canada
2001
2002
2003
22
Attribution
Observations

• Observed changes are consistent with expected
  responses to all forcings
• They are inconsistent with alternative
  explanations

All forcing
Solarvolcanic
23
Intergovernmental Panel on Climate Change 2007
concludes that
Most of the observed increase in globally
averaged temperatures since the mid-twentieth
century is very likely due to the observed
increase in anthropogenic greenhouse gas
concentrations.
24
Climate Change Why Worry?

• How is global climate likely to
• change in the future?

25
IPCC SRES representative emission projections for
the 21st century
26
By 2100, global temperatures are likely to be 1.1
to 6.4C warmer than today
27
Projected temperature changes vary considerably
from year to year
28
Sea levels will rise due to ocean thermal
expansion and change in land ice volume
29
Greenland ice melt will be slow, but could become
catastrophic over decades
30
GCMs project major changes in NH sea ice extent
31
Extreme precipitation events are likely to become
more frequent
Extreme Precipitation Events (Canada)
95
2090
90
85
2050
80
Size of event (mm)
75
1985
70
65
60
55
50
20
40
30
50
60
10
80
70
Event recurrence time (Years)
32
The frequency and severity of droughts are also
likely to increase in southern Canada
33
Climate Change Why Worry?

• Why worry?

34
Potential benefits of warmer temperatures in
temperate regions are significant
and lower space heating costs
35
There will be large shifts in the eventual
distribution of global ecozones
36
There are also many reasons for concern about the
impacts on humans

• A place to live
• sea level rise
• floods
• Food to eat
• crop losses in tropical regions
• droughts
• Health
• extreme weather
• disease/air quality
• Economic well-being

37
Reasons for concern amplify with time, but also
differ in space and time
38
Rising sea levels will significantly affect some
Canadian coastlines
39
Extreme events can cause many types of disasters
40
Climate Change Why Worry?

• What can we do to
• reduce the risks of danger?

41
UN Framework Convention on Climate Change (FCCC)
Ultimate Objective ...to achieve...stabilization
of greenhouse gas concentrations...at a level
that would prevent dangerous interference with
the climate system
42
If emissions and climate sensitivity are high,
most of the world will be in danger by 2100
Projections for A2 scenario with climate
sensitivity of 5.5C
43
Addressing Climate Change Must also Adapt
Climate Change including variability
Impacts autonomous adaptation
Mitigation via GHG sources and sinks
Planned Adaptation
Responses
44
Enhanced adaptation can reduce vulnerability, but
much of the world remains at risk
Projections for A2 scenario, climate sensitivity
of 5.5C, enhanced adaptation
45
Enhanced adaptation and stabilization at 550 ppm
may bring risks to acceptable level
Projections for A2-550 scenario, climate
sensitivity of 5.5C, enhanced adaptation
46
Stabilization at 550 ppm requires 50 reduction
in emissions from current levels
47
Can we enhance natural carbon sinks to partially
offset human emissions?
Global carbon budget in 2000-2005 (GtC/year)
Energy
48
Intergovernmental Panel on Climate Change 2007
concludes that
The range of stabilization levels assessed can
be achieved by deployment of a portfolio of
technologies that are commercially available
today and those that are expected to be
commercialized in coming decades providing
appropriate incentives are in place.
49

To survive in the world we have transformed, we
must learn to think in a new way. As never
before, the future of each depends on the good of
all.
100 Nobel Laureates Oslo, December 2001