Securing Multidisciplinary UndeRstanding and Prediction of Hiatus and Surge events (SMURPHS)

Lead Research Organisation: National Oceanography Centre
Department Name: Science and Technology

Abstract

Climate is currently changing mostly because of additional greenhouse gases, emitted through human activity, which are heating up the planet. Since future warming of climate is likely to cause damage to societies, governments are coordinating efforts to reduce greenhouse gas emissions to avoid these damaging consequences. However, despite the continuing rises in atmospheric greenhouse gas concentrations, the rate of warming of the Earth's surface has declined somewhat since the 1990s. While it is tempting to find a simple reason for this slowing (or "hiatus") in global surface warming, the climate system is extremely complex and there are many factors which can explain the lumps and bumps in the surface temperature record which also include increases (or "surges") in the rate of warming. The goal of our proposed programme of research is to understand much more fully how all the contributing factors can explain past hiatus and surge (H/S) events and this will ultimately help improve predictions of future climate change over the coming decades and far into the future.

The potential causes of H/S events includes: natural (so-called unforced) climate variability, due to complex interplay between the atmosphere, oceans and land; natural climate change due to volcanic eruptions or changes in the brightness of the sun; changes in how heat is moved into the deep oceans due to natural variations or human-caused factors; changes in emissions of gases such as methane due to human activity; limitations in the distribution of temperature observations, such that the hiatus is partly an artefact of imperfect observations. Rather than one single cause it is likely that H/S events are caused by a combination of factors. This is why a large team with a broad range of expertise is required to evaluate the different processes together. Our project, Securing Multidisciplinary UndeRstanding and Prediction of Hiatus and Surge events (SMURPHS) has brought together a comprehensive community of researchers from 9 UK institutes supported by 5 project partners including the Met Office who are experts in the atmosphere, the oceans and the land surface.

SMURPHS has 3 broad objectives, achieved through 6 research themes, which exploit theory, observations and detailed computer modelling. Objective 1 is to build a basic framework for interpreting H/S events in terms of energy moving between the atmosphere and ocean and to determine characteristics of and similarities between H/S events. Objective 2 is to understand mechanisms that could trigger H/S events and extend their length, considering both human and natural factors. Objective 3 is to assess whether H/S events can be predicted and what information is needed for near-term prediction of climate over coming decades which is important for how societies adapt to change. To meet these objectives scientists from a range of different disciplines will work on each of these possibilities and communicate their findings across the team. SMURPHS will produce a wide-ranging synthesis of its results.

SMURPHS will have many beneficiaries. Beyond the global scientific community, improved understanding of H/S events is important at national and international levels for designing policies to control future greenhouse gas emissions and for effective adaptation to climate change. Intergovernmental Panel on Climate Change (IPCC) assessments have deeply influenced climate policy development at the international and national levels. Scientists involved in SMURPHS have contributed significantly to previous IPCC reports, and SMURPHS science and scientists would contribute significantly to future such assessments.

Planned Impact

1. The World Climate Research Program (WCRP) 6th Climate Model Intercomparison (CMIP6) Committee, participating climate research centres, and the international research community will benefit from new radiative forcing scenarios with quantified uncertainties promoted through WCRP/CMIP6 planning meetings. SMURPHS will contribute directly to the CMIP6 plans and host relevant meetings during the project. The SMURPHS webpage will provide the latest information to the international modelling centres and a contact list will be drawn up for provision of regular notifications.
2. International policy makers representing governments in the United Nations Framework Convention on Climate Change (UNFCCC) negotiations; National policy makers in the Department of Energy and Climate Change (DECC) and the Committee for Climate Change (CCC) and European Union counterparts; and International and national non-governmental organisations (NGOs) will benefit from improved understanding of decadal variability in global mean surface temperature rise and of the relationship between short term and longer term trends.
Two critical issues for these groups are: (i) implications of the recent hiatus for long term climate change (mitigation policy), and (ii) constraints on the rate of climate change over the next few decades (adaptation policy). We will organize two international workshops to synthesize research findings and bring together additional international perspectives to provide an overall assessment. Key outputs will be two assessment papers for input to the Sixth Assessment Report of the IPCC (AR6). Lack of complete understanding of the hiatus was a major gap in IPCC AR5, which SMURPHS will address directly. As part of these workshops, a discussion session will be held with invited policymakers from DECC and other government departments to explore the implications of our findings. We also plan to hold a side event on historic temperature trends at a UNFCCC Conference of the Parties (expected in December 2017).
3. The Met Office (MO) has strategic plans to improve near term prediction of climate change and with DECC/DEFRA and CCC will produce revised mitigation pathways to avoid dangerous climate change. The MO will benefit from improved quantification of past radiative forcing and understanding of variability in global-mean surface temperature rise, resulting in improved models and predictions. A close working relationship with the MO is established and a coordinated programme of work has been designed. MO colleagues will attend project meetings and SMURPHS PDRAs will spend time based at the MO. The Met Office Academic Partnership involving the Universities of Exeter, Leeds, Oxford and Reading provides an additional mechanism for collaboration.
4. The general public and the media. SMURPHS will benefit the interested public by enabling clearer and more precise explanations of the hiatus and implications for long-term climate change. Several media articles used poor understanding of the hiatus to challenge the Government's emission reduction targets in 2013. In response the Science Media Centre (SMC) prepared a briefing note on the hiatus with significant contributions from Forster, Sutton, Allan and Hawkins. We will work with the SMC to update this briefing note at the end of the project, and will discuss holding a briefing meeting for interested journalists. Shine is very active in ongoing Royal Society efforts to explain climate change science to a wide audience via a number of activities, and expects to continue to be so during SMURPHS. Outputs from the project will be written up in a form that is accessible for the interested general public on Hawkins' climate-lab-book blog which also provides a mechanism for public engagement and feedback. Key findings will be communicated on Twitter. All PIs and Co-Is have press experience and engagement with the media will continue throughout the project.

Publications

10 25 50
 
Description The amount of heat stored in the intermediate depth layer (1-2km deep) of the North Atlantic Ocean has been increasing in the last decade and this has contributed to the observed global slowdown in surface warming in the 2000s and early 2010s. SMURPHS researchers have found using observations and models that this can be related to a well known quasi periodic shift in the Atlantic climate system from warm to cool and back, known variously as the Atlantic Multidecadal Oscillation, or Atlantic Multidecadal Variability (AMV) which involves coordinated changes in both the oceanic and atmospheric circulation on timescales of a few decades. The amount of heat stored at intermediate depths in the Atlantic thus varies on multidecadal timescales and can modulate the amount of global warming felt at the Earth's surface on the same timescales. There are indications that the AMV is changing from a warm to a cool phase and so our research would suggest that the intermediate depth Atlantic will store less heat in the next few decades and the rate of surface warming will increase.


In a separate study, we have found that the chances of having periods with relatively low surface global warming such as the recent hiatus period are set to become much less likely in the future if greenhouse gas emissions continue to increase, and we are more likely to experience surges in the rate of surface warming. This is because changes in the rate of global surface warming are largely caused by natural variability, including phenomena such as the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation (see above). However the climate models on which our study is based suggest that as the global warming trend in temperature grows stronger, natural variability in temperature will not grow with it and so will have less and less influence on the surface warming trend.

We have performed sensitivity experiments using a climate model to determine the effect on global climate of decadal periods of increased heat uptake such as the recent global surface warming hiatus. The model reproduces the pattern of heat uptake associated with the historical hiatus and shows a strong cooling in the Pacific. We find that the increased heat uptake during the hiatus period results in permanent changes to the ocean stratification which make it more likely that there is a rebound or surge in global mean surface temperature following the hiatus period. The results have important implications for near-term predictability of the climate system.
Exploitation Route prediction of climate change (Intergovernmental Panel on Climate Change), informing mitigation and adaption policies
Sectors Agriculture, Food and Drink,Energy,Environment,Leisure Activities, including Sports, Recreation and Tourism

 
Description We have disseminated our research to a public audience via the BBC South New Programme South Today
First Year Of Impact 2016
 
Description Emergence of Climate Hazards
Amount £1,600,000 (GBP)
Funding ID NE/S004602/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 02/2019 
End 01/2022
 
Description PIRATE: PROBABILISTIC INTERPRETATION OF ALTIMETER & IN-SITU OBSERVATIONS 
Organisation University of Grenoble
Country France 
Sector Academic/University 
PI Contribution Under the SMURPHS Project we have investigated the role of ocean mesoscale processes/intrinsic ocean variability on global ocean heat uptake and found that it is a significant contributor to the global energy budget - which is a substantial contribution to the goals of the PIRATE Project.
Collaborator Contribution Our partners have made made available a 50 member ensemble of NEMO ocean model simulations, not generally available and representing around 300Tb of data for NOC SMURPHS researchers.
Impact A paper on the role of ocean mesoscale processes/intrinsic ocean variability on global ocean heat uptake is in preparation and a presentation will be made at EGU EGU2019-5665 | Orals | CL2.01/AS4.34 How do ocean heat uptake changes influence decadal trends in Earth's energy budget and global mean surface temperature? Bablu Sinha, Jon Robson, and Florian Sevellec Thu, 11 Apr, 11:00-11:15 Room 0.14
Start Year 2016
 
Description Southampton University Diamond Jubilee International Visiting Fellowship 
Organisation University of New South Wales
Country Australia 
Sector Academic/University 
PI Contribution Contributed to travel and accommodation costs for the International Visiting Fellow (Prof Matt England, University of New South Wales) to visit Southampton. Took part in scientific discussions with Prof England and Prof Bob Marsh (Southampton University) in order to design a joint study of the ocean's role in multidecadal climate variability with a focus on links between the Southern Ocean and the North Atlantic.
Collaborator Contribution Prof England (University of New South Wales) participated in the 2017 SMURPHS annual meeting. He contributed an invited talk, provided an evaluation of the science excellence of the project and made suggestions for future scientific directions. Prof England and Prof Bob Marsh (Southampton University) took part in scientific discussions with Dr Bablu Sinha (NOC) in order to design a joint study of the ocean's role in multidecadal climate variability with a focus on links between the Southern Ocean and the North Atlantic.
Impact No outcome yet - scientific collaboration is underway with a joint paper expected in the next year or so
Start Year 2016
 
Description Southampton University Diamond Jubilee International Visiting Fellowship 
Organisation University of Southampton
Department Ocean and Earth Science, National Oceanography Centre Southampton
Country United Kingdom 
Sector Academic/University 
PI Contribution Contributed to travel and accommodation costs for the International Visiting Fellow (Prof Matt England, University of New South Wales) to visit Southampton. Took part in scientific discussions with Prof England and Prof Bob Marsh (Southampton University) in order to design a joint study of the ocean's role in multidecadal climate variability with a focus on links between the Southern Ocean and the North Atlantic.
Collaborator Contribution Prof England (University of New South Wales) participated in the 2017 SMURPHS annual meeting. He contributed an invited talk, provided an evaluation of the science excellence of the project and made suggestions for future scientific directions. Prof England and Prof Bob Marsh (Southampton University) took part in scientific discussions with Dr Bablu Sinha (NOC) in order to design a joint study of the ocean's role in multidecadal climate variability with a focus on links between the Southern Ocean and the North Atlantic.
Impact No outcome yet - scientific collaboration is underway with a joint paper expected in the next year or so
Start Year 2016
 
Description BBC South News Programme Item 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Prof Adrian New, Associate Head of Marine Systems Modelling at the National Oceanography Centre, and Co-Investigator on the SMURPHS project was interviewed for BBC South (local news programme for Southern England, covering Berkshire, Dorset, Hampshire & the Isle of Wight, Surrey, Sussex and Wiltshire) by Alexis Green, on the R.R.S. Discovery foredeck. Prof New Talked about the SMURPHS project, climate change, the global warming hiatus, periods of anomalously strong global warming, and how the North Atlantic affects UK winter conditions. The Interview was broadcast as an item on the BBC South Today Programme on 24/3/2016.
Year(s) Of Engagement Activity 2016