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

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


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.


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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 r
ecent 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.

We have shown that variability intrinsic to the ocean alone (such as mesoscale eddies, and planetary waves modes) can cause the ocean to vary in the amount of heat it takes up from the rest of the climate system over timescales of decades. This extra variability is of order 15-20% of variability from other sources, so needs to be taken into account for near term climate predictions. We found that the North Pacific Ocean, in particular the variations in the strength and position of the Kuroshio Current are responsible for a large part of this intrinsic variability in ocean heat uptake.
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 Citation in the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate
Geographic Reach Multiple continents/international 
Policy Influence Type Citation in systematic reviews
Impact This report is part of the IPCc series of report and as such has helped to change public and government attitudes to climate change and its impacts. This report is expected to have substantial impacts on government policy in respect of climate change adaptation and mitigation policies, both nationally and internationally.
Description (COMFORT) - Our common future ocean in the Earth system - quantifying coupled cycles of carbon, oxygen, and nutrients for determining and achieving safe operating spaces with respect to tipping points
Amount € 8,482,147 (EUR)
Funding ID 820989 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 09/2019 
End 08/2023
Description Consequences of Arctic Warming for European Climate and Extreme Weather
Amount £290,138 (GBP)
Funding ID NE/V004875/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 11/2020 
End 11/2023
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 NI: NEW NORMAL - NEar surface Warming in the INdian Ocean and Rainfall Monsoon Anomaly Links
Amount £101,125 (GBP)
Funding ID NE/W003813/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 08/2021 
End 07/2023
Description Wider Impacts of Subpolar nortH atlantic decadal variaBility on the OceaN and atmospherE' (WISHBONE)
Amount £285,007 (GBP)
Funding ID NE/T013540/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 09/2020 
End 08/2023
Title Intermediate resolution climate model FORTE2 
Description This is a significantly updated version of a fast, inexpensive and low resolution coupled climate model developed previously at the National Oceanography Centre and used for idealised climate experiments.The updated version now runs on parallel processors using MPI software, has a more advanced atmospheric component including a resolved stratosphere and can simulate 300+ model years in 1 day of real time. This opens up the possibility of investigating paleaoclimate with a full primitive equation model, as well as studying contemporary climate and performing climate projections at a fraction of the cost of standard CMIP-style climate models. In particular the model is readily configurable, allowing control over land geometry and orography, ocean topography, and geophysical parameters such as rotation rate, solar input, orbital parameters etc. 
Type Of Material Improvements to research infrastructure 
Year Produced 2021 
Provided To Others? Yes  
Impact As it has just been released, impact is restricted to the publication which documents the model performance 
Title Fast, Parallel intermediate complexity climate model (FORTE 2.0) 
Description This is a climate model with relatively low resolution (2.8 degrees in the atmosphere and 2 degrees in the ocean), but optimised for MP and open MP parallel processing so that it is fast enough to multicentennial and millennial climate simulations. It is easily configurable so that different continental and orographic/ocean bathymetry configurations can be explored. The model can be run with our without a stratosphere. There are basic thermodynamic sea ice and land soi/vegetation models 
Type Of Technology Software 
Year Produced 2021 
Open Source License? Yes  
Impact As this has only just been released, we are expecting impacts to build up over time. A paper has been published describing the model: FORTE 2.0: a fast, parallel and flexible coupled climate model. Blaker, A., Joshi, M., Sinha, B., Stevens, D., Smith, R. & Hirschi, J., 19 Jan 2021, In : Geoscientific Model Development. 14, 1, p. 275-293 19 p.