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1. IPCC 5th Assessment of Climate Change Science – a Welsh perspective
The Fifth Assessment Report (AR5): Key
messages and the Welsh contribution
James Scourse
Director, Climate Change Consortium of Wales
(C3W)
School of Ocean Sciences, Bangor University

2. Atmospheric CO2 concentrations are now at an unprecedented
level compared with the last 800,000 years
Atmospheric CO2 concentrations have
– increased by about 40% since 1750, due to human activity
– exceed values recorded in ice cores for the last 800,000 years
IPCC AR5 2013

4. Methane has increased by 150% and nitrous oxide by
20% since 1750
Methane:
CH4
Mauna
Loa
South Pole
Nitrous Oxide:
N2O
Mace Head
Cape Grim
IPCC AR5 2013

5. Stronger evidence that observed warming is linked to
human influence
IPCC AR5 2013

6. •
It is extremely likely (95-100%) that most of observed increase in global
surface temperature since 1951 caused by human influence
•
Observed ocean warming can now be attributed to human influence with
greater confidence (attribution statement likely in AR4 and very likely in AR5)
•
For 1951-2010 observed warming of 0.6˚C: greenhouse gases contributed
0.5 to 1.3˚C, aerosols -0.6 to 0.1˚C and natural forcings -0.1 to 0.1˚C
•
Over every continental region, except Antarctica, human influence has
made substantial contribution to surface temperature increases
IPCC AR5 2013

7. Projections of global average warming
•
•
•
By the end of the century, the increase of global mean surface temperature above 19862005 levels is projected to be:
– 0.3-1.7˚C for RCP2.6
– 2.6-4.8˚C for RCP8.5
Global warming >2˚C is likely for RCP6.0 and RCP8.5
Global warming >4˚C is unlikely except for RCP8.5
IPCC AR5 2013

8. Warming will not be the same everywhere
•
•
There is very high confidence that long-term warming will be larger over land than
over the ocean, and that the Arctic region will warm most rapidly
Ocean warming will continue for centuries, even if greenhouse gas emissions are
IPCC AR5 2013
decreased

9. http://www.nasa.gov/topics/earth/features/2012-temps.html

10. There will be large geographical variations
in precipitation change
•
•
•
For the next few decades, changes in regional-scale precipitation will be strongly influenced
by natural variability
Contrast between wet and dry regions and seasons will increase over most of the globe,
though there are regional exceptions
Monsoon precipitation is likely to intensify, along with a lengthening of the monsoon season
IPCC AR5 2013

11. Arctic sea ice projected to decline
Northern hemisphere September sea ice extent
•
RCP2.6
RCP8.5
•
•
1950
2000
2100
2050
Very likely (90-100%) that Arctic sea ice cover will
continue to shrink and thin
Projected reductions in sea ice extent for
September by end of century are 43% for RCP2.6
and 94% for RCP8.5
A nearly ice-free Arctic Ocean in September is
likely (66-100%) before mid-century under RCP8.5
IPCC AR5 2013

12. Sea-level rise will continue
•
•
•
Global average sea level will rise during the 21st century, and it is very likely that it will rise faster
than it has during the last 40 years
Thermal expansion accounts for 30-55% of the total, with melting of glaciers giving the second
largest contribution
It is likely that reductions in the Greenland and Antarctic ice sheets will contribute to sea level rise
IPCC AR5 2013
by 0.03-0.20m by 2100

13. Between 1993 and 2010 observed global mean sea level rise was 3.2 [2.8 to
3.4] mm per year
• 1.1 [0.8 to 1.4] mm per year: thermal expansion
•
•
•
•
0.76 [0.39 to 1.13] mm per year: glaciers except Greenland and Antarctica
0.10 [0.07 to 0.13] mm per year: Greenland glaciers
0.33 [0.25 to 0.41] mm per year: Greenland Ice Sheet
0.27 [0.16 to 0.38] mm per year: Antarctic Ice Sheet
• 0.38 [0.26 to 0.49] mm per year: land water storage
• BUT: 3.2 mm per year is a GLOBAL AVERAGE
IPCC AR5 2013

14. Spatial variation in global sea-level rise
1993 to 2008 based on Topex/Poseidon
and Jason-1 satellites [climate.nasa.gov]

15. Vertical land motion (mm/yr)
Geological data
Gehrels (2010)
GIA model

16. Larsen B ice shelf collapse
2002

17. Additional contributions from the ice
sheets?
• During last interglacial, high confidence that maximum
global mean sea level was 5-10 m higher than present
• Only collapse of marine based sectors of the Antarctic
Ice Sheet, if initiated, could cause global mean sea level
to rise substantially above the likely range during the 21st
century
• Medium confidence that this additional contribution
would not exceed several tenths of a meter of sea level
rise during the 21st century
IPCC AR5 2013

18. Human contribution to changes in weather
extremes
Phenomenon
Global changes since
1950
Human contribution
Fewer cold days and
nights
Very likely
Very likely
More hot days and
nights
Increase in heat waves
Very likely
Very likely
Medium confidence
Likely
Increase in heavy
precipitation
Likely
Medium confidence
Increase in drought
Low confidence
Low confidence
Increase in tropical
cyclone activity
Low confidence
Low confidence
IPCC AR5 2013

19. The contribution of Welsh science to IPCC AR5: The
Physical Science Basis
Chapter 4 Lead Author: Tavi Murray (Swansea University)
Chapter 13 Contributing Author: Tavi Murray (Swansea University)
Chapter 5 Contributing Author: Paul Pearson (Cardiff University)
32 cited scientific articles:
8 in Chapter 4 (Cryosphere)
20 in Chapter 5 (Paleoclimate)
2 in Chapter 6 (Carbon and Other Biogeochemical Cycles)
1 in Chapter 7 (Clouds and Aerosols)
1 in Chapter 14 (Climate Phenomena and their Relevance for Future
Regional Climate Change)

20. Swansea and Aberystwyth universities internationally very strong in
glaciological/cryospheric research, especially related to the Greenland Ice Sheet
Cardiff, Bangor, Swansea and Aberystwyth universities all internationally very strong
in paleoclimate research, especially in marine paleoclimate research

21. Chapter 4 (Cryosphere): cited scientific articles
ABERYSTWYTH: Carrivick, J. L., B. J. Davies, N. F. Glasser, D. Nyvlt, and M. J. Hambrey, 2012: Late-Holocene changes in
character and behaviour of land-terminating glaciers on James Ross Island, Antarctica. Journal of Glaciology, 58 , 1176-1190
ABERYSTWYTH: Davies, B. J., and N. F. Glasser, 2012: Accelerating shrinkage of Patagonian glaciers from the “Little Ice
Age” (c. AD1870) to 2011. Journal of Glaciology, 58 , 1063-1084.
SWANSEA: Luckman, A., and T. Murray, 2005: Seasonal variation in velocity before retreat of Jakobshavn Isbrae, Greenland.
Geophysical Research Letters, 32 , 4
SWANSEA: Murray, T., T. Strozzi, A. Luckman, H. Jiskoot, and P. Christakos, 2003: Is there a single surge mechanism?
Contrasts in dynamics between glacier surges in Svalbard and other regions. Journal of Geophysical Research-Solid
Earth,108 , 2237.
SWANSEA: Murray, T., Scharrer, K., James, T.D., Dye, S.R., Hanna, E., Booth, A.D., Selmes, N., Luckman, A., Hughes,
A.L.C., Cook, S. and Huybrechts, P. 2010: Ocean regulation hypothesis for glacier dynamics in southeast Greenland and
implications for ice sheet mass changes. Journal of Geophysical Research-Earth Surface, 115 , F03026.
ABERYSTWYTH/SWANSEA: Quincey, D. J., M. Braun, N. F. Glasser, M. P. Bishop, K. Hewitt, and A. Luckman, 2011:
Karakoram glacier surge dynamics. Geophysical Research Letters, 38 , L18504.
SWANSEA: Selmes, N., T. Murray, and T. D. James, 2011: Fast draining lakes on the Greenland Ice Sheet. Geophysical
Research Letters, 38 , 5 (L15501).
ABERYSTWYTH: Shepherd, A., A. Hubbard, P. Nienow, M. King, M. McMillan, and I. Joughin, 2009: Greenland ice sheet
motion coupled with daily melting in late summer. Geophysical Research Letters , 36 , L01501.

22. Chapter 5 (Paleoclimate): cited scientific articles
CARDIFF: Barker, S., G. Knorr, M. J. Vautravers, P. Diz, and L. C. Skinner, 2010: Extreme deepening of the Atlantic
overturning circulation during deglaciation. Nature Geoscience, 3 , 567-571.
CARDIFF: Barker, S., P. Diz, M. J. Vautravers, J. Pike, G. Knorr, I. R. Hall, and W. S. Broecker, 2009: Interhemispheric
Atlantic seesaw response during the last deglaciation. Nature, 457 , 1097-1102.
CARDIFF: Barker, S., Knorr, G., Edwards, R.L., Parrenin, F., Putnam, A.E., Skinner, L.C., Wolff, E. and Ziegler, M:
800,000 Years of Abrupt Climate Variability. Science, 334 , 347-351.
ABERYSTWYTH: Bentley, M. J., C. J. Fogwill, A. M. Le Brocq, A. L. Hubbard, D. E. Sugden, T. J. Dunai, and S. P. H. T.
Freeman, 2010: Deglacial history of the West Antarctic Ice Sheet in the Weddell Sea embayment: Constraints on past
ice volume change. Geology, 38 , 411-414.
BANGOR: Cunningham, L.K., Austin, W.E.N., Knudsen, K.L., Eiríksson, J., Scourse, J.D., Wanamaker, A.D., Jr, Butler,
P., Cage, A., Richter, T., Husum, K., Hald, M., Andersson, C., Zorita, E., Linderholm, H., Gunnarson, B.E., Sicre, M.A.,
Sejrup, H.P., Jiang, H. & Wilson, R.J.S. 2013. Reconstructions of surface ocean conditions from the North East Atlantic
and Nordic Seas during the last millennium. The Holocene, 23, 921-935.
CARDIFF: Elderfield, H., Greaves, M., Barker, S., Hall, I.R., Tripati, A., Ferretti, P., Crowhurst, S., Booth, L. and Daunt,
C. 2010: A record of bottom water temperature and seawater δ 18O for the Southern Ocean over the past 440 kyr based
on Mg/Ca of benthic foraminiferal Uvigerina spp. Quaternary Science Reviews, 29, 160-169.
CARDIFF: Ellison, C. R. W., M. R. Chapman, and I. R. Hall, 2006: Surface and deep ocean interactions during the cold
climate event 8200 years ago. Science, 312 , 1929-1932.

23. Chapter 5 (Paleoclimate): cited scientific articles
CARDIFF: Foster, G. L., C. H. Lear, and J. W. B. Rae, 2012: The evolution of pCO2 , ice volume and climate during the
middle Miocene. Earth and Planetary Science Letters, 341–344 , 243-254.
CARDIFF: Hall, I. R., S. B. Moran, R. Zahn, P. C. Knutz, C. C. Shen, and R. L. Edwards, 2006: Accelerated drawdown
of meridional overturning in the late-glacial Atlantic triggered by transient pre-H event freshwater perturbation.
Geophysical Research Letters, 33 , L16616.
SWANSEA: Hughes, A. L. C., E. Rainsley, T. Murray, C. J. Fogwill, C. Schnabel, and S. Xu, 2012: Rapid response of
Helheim Glacier, southeast Greenland, to early Holocene climate warming. Geology, 40 , 427-430.
CARDIFF: Kleiven, H. F., I. R. Hall, I. N. McCave, G. Knorr, and E. Jansen, 2011: Coupled deep-water flow and climate
variability in the middle Pleistocene North Atlantic. Geology, 39 , 343-346.
CARDIFF: Köhler, P., G. Knorr, D. Buiron, A. Lourantou, and J. Chappellaz, 2011: Abrupt rise in atmospheric CO2 at
the onset of the Bølling/Allerød: in-situ ice core data versus true atmospheric signals. Climate of the Past, 7, 473-486.
CARDIFF: Lynch-Stieglitz, J., Adkins, J.F., Curry, W.B., Dokken, T., Hall, I.R., Herguera, J.C., Hirschi, J.J.M., Ivanova,
E.V., Kissel, C., Marchal, O., Marchitto, T., McCave, I.N., McManus, J.F., Mulitza, S., Ninnemann, U., Peeters, F., Yu,
E.F. and Zahn, R. 2007: Atlantic meridional overturning circulation during the Last Glacial Maximum. Science, 316 , 6669.
ABERYSTWYTH: Macklin, M. G., J. Lewin, and J. C. Woodward, 2012: The fluvial record of climate change.
Philosophical Transactions of the Royal Society, Series A , 370 , 2143-2172.

24. Chapter 5 (Paleoclimate): cited scientific articles
SWANSEA: McCarroll, D., Loader, N.J., Jalkanen, R., Gagen, M.H., Grudd, H., Gunnarson, B.E., Kirchhefer, A.J.,
Friedrich, M., Linderholm, H.W., Lindholm, M., Boettger, M., Los, S.O., Remmele, S., Kononov, Y.M., Yamazaki, Y.U.,
Young, G.H.F. and Zorita, E. 2013: A 1200-year multiproxy record of tree growth and summer temperature at the
northern pine forest limit of Europe. The Holocene, 23, 471-484.
SWANSEA: NEEM community members (including S.M. Davies), 2013 : Eemian interglacial reconstructed from
Greenland folded ice core. Nature, 493 , 489-494.
CARDIFF: Pearson, P. N., G. L. Foster, and B. S. Wade, 2009: Atmospheric carbon dioxide through the EoceneOligocene climate transition. Nature, 461 , 1110-1113.
CARDIFF: Sosdian, S., and Y. Rosenthal, 2009: Deep-sea temperature and ice volume changes across the PliocenePleistocene climate transitions. Science, 325, 306-310.
BANGOR: Trouet, V., J. Esper, N. E. Graham, A. Baker, J. D. Scourse, and D. C. Frank, 2009: Persistent positive north
Atlantic oscillation mode dominated the Medieval Climate Anomaly. Science, 324 , 78-80.
SWANSEA: Wilson, R., D. Miles, N. Loader, T. Melvin, L. Cunningham, R. Cooper, and K. Briffa, 2013. A millennial long
March–July precipitation reconstruction for southern-central England. Climate Dynamics, 40, 997-1017.

25. Chapter 6 (Carbon and Other Biogeochemical Cycles): cited scientific articles
BANGOR: Evans, C. D., D. T. Monteith, and D. M. Cooper, 2005: Long-term increases in surface water dissolved
organic carbon: observations, possible causes and environmental impacts. Environmental Pollution, 137 , 55-71.
CARDIFF: Skinner, L. C., S. Fallon, C. Waelbroeck, E. Michel, and S. Barker, 2010: Ventilation of the deep Southern
ocean and deglacial CO2 rise. Science, 328, 1147-1151.
Chapter 7 (Clouds and Aerosols): cited scientific article
SWANSEA:Gagen, M., Zorita, E., McCarroll, D., Young, G.H.F., Grudd, H., Jalkanen, R., Loader, N., Robertson, I. and
Kirchhefer, A., 2011. Cloud response to summer temperatures in Fennoscandia over the last thousand years.
Geophysical Research Letters, 38, L05701.
Chapter 14 (Climate Phenomena and their Relevance for Future Regional
Climate Change): cited scientific article
ABERYSTWYTH: Metcalfe, S. E., M. D. Jones, S. J. Davies, A. Noren, and A. MacKenzie, 2010: Climate variability
over the last two millennia in the North American Monsoon, recorded in laminated lake sediments from Laguna de
Juanacatlan. Mexico. The Holocene, 20 , 1195-1206.

26. UN Intergovernmental Panel on
Climate Change (IPCC):
Assessment Report 4, 2007
“the gold standard in scientific
reference on all aspects of climate
change for governments, industry
and individuals worldwide”
IPCC Fifth Assessment Report
(AR5)
The Physical Science Basis, September 2013
Impacts, Adaptation and Vulnerability, March
2014
Mitigation, April 2014
Synthesis, October 2014