The Science of Climate Change

1
The Science of Climate Change

• the climate connection
• a public health partnership for action

2
Learning objectives

• The greenhouse gases
• Observed changes to global temperatures,
  glaciers, sea level, extreme weather events
• Uncertainties in future projections
• Climate change and ecosystems
• A challenge to Public Health

3
Without atmospheric gases, the earths average
surface temperature would be below freezing
4
Greenhouse Gases

• water vapour
• carbon dioxide
• methane
• ozone
• nitrous oxide
• CFCs (and HFCs)

5
Human activitiesglobal emissions by sector, 2000
Source http//en.wikipedia.org/wiki/FileGreenhou
se_Gas_by_Sector.png based on data from the
Emission Database for Global Atmospheric Research
version 3.2, fast track 2000 project
6
The Carbon Cycle
Carbon dioxide is released and reabsorbed in a
natural cycle. Human activities now release it
more quickly than it can be reabsorbed
Source NASA Earth Observatory
7
Human activitiesfossil fuel burning
350 million years-worth of carbon locked away in
fossil fuels now being released
150 years
100 years
50 years
NOW
600,000,000 cars4,000,000,000 passenger flights
First Oil Well
4000 cars in USA
First commercial jet ticket
Sustainable
Development Unit
8
Livestock farming accounts for 18 global
emissions
Human activitieslivestock farming

• CO2 released from deforestation (34)
• Methane from enteric fermentation (25)
• Methane and N2O from manure (30)
• CO2 from fossil fuels in production of
  fertilisers - which also cause release of N2O
  (6)
• Other (4)

9
Are greenhouse gas concentrations rising?
10
Source IPCC 4th Assessment Report
11
Are temperatures rising?
Figure 3.1. Annual anomalies of global
land-surface air temperature (C), 1850 to 2005,
relative to the 1961 to 1990 mean.
Source IPCC 4th Assessment Report
12
(No Transcript)
13
(No Transcript)
14

• Melting of glaciers (and of the Greenland and
  Antarctic ice sheets) is contributing to rising
  sea levels. Sea levels are also rising due to
  expansion of the water as it warms.

15
2004 Hurricane Catarina the first South
Atlantic hurricane.
16

• Warmer seas give rise to more forceful tropical
  storms.
• In March 2004, Hurricane Catarina, was the first
  South Atlantic cyclone to reach hurricane
  intensity.

17
Arent temperature variations a natural
phenomenon?
18

• Natural cycles occur due to tilt of the earth in
  relation to the sun, and volcanic eruptions
  releasing particles into the air.
• Based on those factors, models would predict a
  cooling over the last 50 years.
• Only when human activities are factored in, are
  the current temperature rises explained.

19
Arent even scientists unsure about global
warming?
20
The IPCC

• More than 2,500 scientific expert reviewers were
  involved in the Intergovernmental Panel on
  Climate Change (IPCC) 2007 report. The report
  concludes
• Warming of the climate system is unequivocal.
• Greenhouse gas concentrations have increased as a
  result of human activities.
• There is very high confidence that the net
  effect of human activities since 1750 has been
  one of warming. gt9/10 probability

Source IPCC 4th Assessment Report (2007)
21
The uncertainty is not about whether climate
change is happening, but about what it will mean,
and how we should respond.
22
IPCC Scenarios
Projections of global temperatures 2000-2100
under different scenarios of population growth
and development patterns
Source IPCC Fourth Assessment Report
23
Impact of climate change on ecosystems

• Rapid ecosystem change due to
• increased climatic variation (droughts, fires and
  floods)
• warming and acidification of seas
• deforestation
• expansion of deserts
• Loss of biodiversity as species unable to migrate
  between fragmented habitats

24
Impact of climate change on ecosystems

• We may be in the midst of the Sixth Great
  Extinction event in prehistory
• Three species are lost every hour

25
Sixth Extinction Event
26
The Precautionary PrincipleRisks not yet
included in the IPCC

• Arctic ice sheet melting more rapidly than
  expected
• Albedo effect rapid warming as heat-reflective
  snow and ice caps shrink
• Accelerated release of methane from permafrost
  and oceans
• Reduced absorption of CO2 by warming seas
• Unpredictability of climate system
• NASA climate scientist Dr James Hansen has
  revised the safe upper level of CO2 from 450 to
  350ppm

27
Are we too late?
28
Yes, but more importantly, NO!

• We are too late to avoid global warming
  altogether its already here.
• Warming will continue due to greenhouse gases
  already released.
• NOT TOO LATE to save 20 species, prevent gt2
  degrees rise, and keep the climate within the
  range in which human civilisations evolved

29
Climate change the greatest challenge ever
faced in public health

• migration
• food security
• flooding
• heatwaves
• energy poverty
• vector-borne disease
• inequalities

30
Climate change the greatest challenge ever
faced in public health

• halting fossil fuel emissions
• reforestation
• soil management
• Should these be seen as health interventions?

31
References

• Global emissions by sector, 2000 prepared by
  Robert A. Rohde from publicly available
  datahttp//en.wikipedia.org/wiki/FileGreenhouse_
  Gas_by_Sector.png
• The Carbon Cycle NASA Earth Observatory
• Global Warning climate change and farm animal
  welfare, report by Compassion in World Farming
  (2007)
• Intergovernmental Panel on Climate Change Fourth
  Assessment Report (2007) URL
• Rohde, R.A., and Muller, R.A. (March 2005).
  "Cycles in fossil diversity". Nature 434
  208-210.
• Target Atmospheric CO2 Where Should Humanity
  Aim? James Hansen et al, Cornell University
  Library arXiv.org

32
The Climate Connection is a partnership for
public health action on climate change
The Climate Connection, c/o UKPHA, 94 White Lion
St, London N1 9PF UKPHA registered charity number
1078147 www.theclimateconnection.org