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Climate Change Our Present State of Understanding. Humboldt State University 06 April MMX. Jelte Harnmeijer NASA Astrobiology Institute & Department of Earth and Space Sciences University of Washington. }. (former affiliation). What’s in a name?. ‘Greenhouse effect’. - PowerPoint PPT Presentation
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Climate Change
Our Present State of Understanding
Jelte Harnmeijer
NASA Astrobiology Institute
&
Department of Earth and Space Sciences
University of Washington
(former affiliation)}
Humboldt State University06 April MMX
What’s in a name?
‘Greenhouse effect’
What’s in a name?
‘Greenhouse effect’
‘Global warming’
What’s in a name?
‘Greenhouse effect’
‘Global warming’
‘Climate change’
What’s in a name?
‘Greenhouse effect’
‘Global warming’
‘Climate change’
‘Global climate destabilization’
climate, n. The characteristic weather conditions of a country or region; the prevalent pattern of weather in a region throughout the year, in respect of variation of temperature, humidity, precipitation, wind, etc., esp. as these affect human, animal, or plant life.
What’s in a name?
The People
Science
Policy
What’s in a name?
The People
Science
Policy
What’s in a name?
The People
Science
PolicyMedia
Corporations
Climate change is real ...
IPCC (2007)
Climate change is real ...
IPCC (2007)
Gruber & Galloway (2009)
... and humans are to blame
IPCC (2007)
... and humans are to blame
• Temperatures are increasing
• Heat waves are increasing
• Heavy precipitation events are increasing
• Snow cover is diminishing
• Weather is becoming less ‘climate-like’:
o Less predictability
o Greater amplitude variations with higher frequency
The Atmosphere Subsystem
Secular changes do not pose the primary threat
How will greenhouse gas emissions trend?
(1) Hydrocarbon demand, supply & availability
ITPOES (2010)
How will greenhouse gas emissions trend?
(1) Hydrocarbon demand, supply & availability
How will greenhouse gas emissions trend?
(2) Population
How will greenhouse gas emissions trend?
(2) Population
• ~9 billion people predicted by 2050
• China’s population has stabilized
• ~ +750 million in India
• Most newcomers in sub-Saharan Africa
How will greenhouse gas emissions trend?
(3) Industrialization / ‘Development’
How will greenhouse gas emissions trend?
(3) Industrialization / ‘Development’
• Developing countries currently provide almost half of the world’s primary commodity exports, whilst importing less than a third.
• Industrializing today’s ~5 billion un-industrialized people and the net 3 billion newcomers would entail ~sextupling primary commodity output
Geological context
Zachos (2009)
Geological context
• Anthropocene CO2 concentrations *not* unprecedented
• Anthropocene temperatures *not* unprecedented
• But pace of change is paramount
• Great future unknowns:
o N2O
o CH4
o ocean structure & circulation
o cloud behaviour
Geological context
Positive feedback mechanisms accelerate change
Examples:
• Ice-albedo feedback
• Carbonate dissolution-ocean acidification
Geological context
Negative feedback mechanisms limit change
Examples:
• Calc-silicate feedback cycle
The Ocean Subsystem
• In contrast to our atmosphere, our oceans equilibrate slowly
• Timescale of 103 - 104 years typical
• Over the coming centuries, physicochemical response of our oceans will strongly control climate
• Marine biogeochemical cycling regulates key greenhouse gases
The Ocean Subsystem
Our oceans have absorbed ~1/3 of anthropogenic CO2 ...
CO2 flux [moles m-2 year-1]
The Ocean Subsystem
Our oceans have absorbed ~1/3 of anthropogenic CO2 ...
... but there is a price to pay:
pH ≈ - log10 [H+]
The Ocean Subsystem
Our oceans have absorbed ~1/3 of anthropogenic CO2 ...
... but there is a price to pay:
Some CO2 dissolves: CO2 (g) = H2CO3 (aq)
Which produces acidity: H2CO3 (aq) = H+ (aq) + HCO3
-
(aq)
Which dissolves carbonate:CaCO3 + 2H+ (aq) = Ca2+
(aq) + H2O + CO2
Which produces more CO2 ...
pH ≈ - log10 [H+]
The Ocean SubsystemImplicated carbonate biosynthesizers:
• Coccolithophores
• Cnideria
(coral reefs, ...)
• Foraminifera
• Echinoderms
(starfish, sea urchins, ...)
• Crustaceans
(crab, lobster, shrimp, crayfish, krill, barnacles, ...)
• Molluscs
(bivalves, ...)
The Ocean Subsystem
Stramma et al. (2008)
The Ocean Subsystem
Stramma et al. (2008)
The Ocean Subsystem
• Temperatures are increasing
• pH is decreasing
• Oxygen Minimum Zones are expanding
• Intense tropical cyclone activity is increasing
• Sea level is rising
Thinking ahead
Prevent?
or
Adapt?
Thinking ahead
hope, n. – Gr.: ελπίς (elpis)
Thinking ahead
“anticipation of misfortune”
hope, n. – Gr.: ελπίς (elpis)
Thinking ahead
IPCC (2007)
IPCC (2007)
Thinking ahead
Thinking ahead
Hawking (2007)
“... the worst case scenario is that Earth
would become like its sister planet, Venus.”
Thinking ahead
Planet Venus Earth
Density [g/cm3] 5.24 5.52
Radius [km] 6052 6378
Mass [·1024 kg] 4.86 5.97
Sidereal Orbit Period [Earth years] 0.62 1.00
Sidereal Rotation Period [Earth days] 243 1.00
Surface temperature [K] 730 288-293
Major atmospheric constituentsCO2, N2
N2, O2
Distance from Sun [A.U.] 0.72 1.00
Thinking ahead
Thinking ahead
Lovelock (2005)
Thinking ahead
Prevent?
or
Adapt?
(Coping not an option)
Thinking ahead
Solomon (2009)
Post-hydrocarbon
decay will be
slow
http://www.realfuture.org
• This presentation
• Further resources
• Feedback & discussion
