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

IPCC 5th Assessment of Climate Change Science – a Welsh perspective

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

Methane has increased by 150% and nitrous oxide by

20% since 1750

Methane: CH4

Nitrous Oxide: N2O

Mauna Loa

South Pole

Mace Head

Cape Grim

IPCC AR5 2013

Stronger evidence that observed warming is linked to

human influence

IPCC AR5 2013

• 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

Projections of global average warming

• By the end of the century, the increase of global mean surface temperature above 1986-

2005 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

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

decreased IPCC AR5 2013

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

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

Arctic sea ice projected to decline

Northern hemisphere September sea ice extent

1950 2000 2050 2100

RCP2.6

RCP8.5

• 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

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

by 0.03-0.20m by 2100 IPCC AR5 2013

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

Spatial variation in global sea-level rise

1993 to 2008 based on Topex/Poseidon

and Jason-1 satellites [climate.nasa.gov]

Vertical land motion (mm/yr)

Geological data GIA model Gehrels (2010)

Larsen B ice shelf collapse

2002

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

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

Very likely Very likely

Increase in heat waves 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

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)

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

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.

Chapter 4 (Cryosphere): cited scientific articles

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 δ18O 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.

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 , 66-

69.

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.

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 Eocene-

Oligocene climate transition. Nature, 461 , 1110-1113.

CARDIFF: Sosdian, S., and Y. Rosenthal, 2009: Deep-sea temperature and ice volume changes across the Pliocene-

Pleistocene 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.

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.

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