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Shutting down the
thermohaline circulation
David Anthoff
University of California, Berkeley
Francisco Estrada
Universidad ...
Key concern
• Climate change could lead to
• More rain over the North Atlantic
• Melting of the Greenland Ice Sheet
• This...
WE FEAR THE COLD
-25.0
-22.5
-20.0
-17.5
-15.0
-12.5
-10.0
-7.5
-5.0
-2.5
0.0
2.5
5.0
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4....
-20
-15
-10
-5
0
5
10
100 1,000 10,000 100,000
Welfare-equivalentincomechange(inpercent)
Income (in 2005 dollar per person...
-25.0
-22.5
-20.0
-17.5
-15.0
-12.5
-10.0
-7.5
-5.0
-2.5
0.0
2.5
5.0
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4....
Hosing
• Coupled atmosphere-ocean general circulation
models project a slight weakening of the
thermohaline circulation
• ...
-6
-5
-4
-3
-2
-1
0
1temperaturechange(degreecentigrade)
Hadley 0.3
Hadley 0.1
BCM 0.1
IPSL 0.1
-7
-6
-5
-4
-3
-2
-1
0
1
-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6
Welfaregain(%income)
Warming (degre...
-4
-2
0
2
4
6
8welfareimpact(percentincome)
Hadley 0.3
Hadley 0.1
BCM 0.1
IPSL 0.1
-10
-8
-6
-4
-2
0
2
4
6
8welfareimpact(percentincome)
Hadley 0.3
Hadley 0.1
BCM 0.1
IPSL 0.1
Wrap-up
• Warming is bad, cooling is worse
• The cooling due to a shut- or slowdown of the
thermohaline circulation is mod...
Impact of a thermohaline circulation slowdown
Impact of a thermohaline circulation slowdown
Impact of a thermohaline circulation slowdown
Impact of a thermohaline circulation slowdown
Impact of a thermohaline circulation slowdown
Impact of a thermohaline circulation slowdown
Impact of a thermohaline circulation slowdown
Impact of a thermohaline circulation slowdown
Impact of a thermohaline circulation slowdown
Impact of a thermohaline circulation slowdown
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Impact of a thermohaline circulation slowdown

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Publié le

Lecture on the economic impacts of a slowdown of the thermohaline circulation, Richard Tol, 9 December 2015, Falmer.

Publié dans : Sciences
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Impact of a thermohaline circulation slowdown

  1. 1. Shutting down the thermohaline circulation David Anthoff University of California, Berkeley Francisco Estrada Universidad Nacional Autónoma de Mexico Richard S.J. Tol University of Sussex, Vrije Universiteit Amsterdam, Tinbergen Institute, CESifo
  2. 2. Key concern • Climate change could lead to • More rain over the North Atlantic • Melting of the Greenland Ice Sheet • This would lead to a drop in salinity and may slow- down – or even shut-down – the thermohaline circulation
  3. 3. WE FEAR THE COLD
  4. 4. -25.0 -22.5 -20.0 -17.5 -15.0 -12.5 -10.0 -7.5 -5.0 -2.5 0.0 2.5 5.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 Welfare-equivalentincomechange(inpercent) Global warming (in degrees centrigrade)
  5. 5. -20 -15 -10 -5 0 5 10 100 1,000 10,000 100,000 Welfare-equivalentincomechange(inpercent) Income (in 2005 dollar per person per year)
  6. 6. -25.0 -22.5 -20.0 -17.5 -15.0 -12.5 -10.0 -7.5 -5.0 -2.5 0.0 2.5 5.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 Welfare-equivalentincomechange(inpercent) Global warming (in degrees centrigrade) Fit same function per country: Optimum temperature: 0.3K, range -3 - +7K above today Slopes vary from zero to 28%Y/K
  7. 7. Hosing • Coupled atmosphere-ocean general circulation models project a slight weakening of the thermohaline circulation • The impact of a more drastic weakening are studied using so-calling hosing experiments, in which a Death Star suddenly appears to spout freshwater into the North Atlantic
  8. 8. -6 -5 -4 -3 -2 -1 0 1temperaturechange(degreecentigrade) Hadley 0.3 Hadley 0.1 BCM 0.1 IPSL 0.1
  9. 9. -7 -6 -5 -4 -3 -2 -1 0 1 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 Welfaregain(%income) Warming (degree centigrade) Modest warming due to greenhouse gases, severe cooling due to thermohaline circulation shutdown Severe warming due to greenhouse gases, modest cooling due to thermohaline circulation shutdown
  10. 10. -4 -2 0 2 4 6 8welfareimpact(percentincome) Hadley 0.3 Hadley 0.1 BCM 0.1 IPSL 0.1
  11. 11. -10 -8 -6 -4 -2 0 2 4 6 8welfareimpact(percentincome) Hadley 0.3 Hadley 0.1 BCM 0.1 IPSL 0.1
  12. 12. Wrap-up • Warming is bad, cooling is worse • The cooling due to a shut- or slowdown of the thermohaline circulation is modest relative to the warming that would induce that. • Reduced warming would lead to a welfare gain in most countries

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