CLIVAR Research Foci

-- Decadal climate variability and predictability (DCVP) --

-- Eastern Boundary Upwelling Systems (EBUS) --

-- Regional Sea Level Change and Coastal Impacts --

-- Understanding and predicting weather and climate extremes --

-- ENSO in a changing climate --

-- Consistency between planetary energy balance and ocean heat storage (CONCEPT-HEAT) --



Decadal climate variability and predictability (DCVP)

Figure: Twenty-first-century projections of SST (top) and North Atlantic Tropical Storm frequency (bottom) using CMIP5 (Villarini and Vecchi 2012)Twenty-first-century projections of SST (top) and North Atlantic Tropical Storm frequency (bottom) using CMIP5 (Villarini and Vecchi 2012)

Decadal climate variability (DCV) – the variations in global and regional climate that distinguish one decade from another – is of relevance to our complex modern society. DCV can arise from internal interactions within the climate system, and in response to external forcing such as clusters of volcanic eruptions and changes in solar irradiance. These natural expressions of decadal variability interact with the impact of anthropogenic forcing, namely changes in industrial aerosol, land use, and greenhouse gas emissions and either exacerbate or mitigate their impact. DCV impacts the background in which higher frequency variations (i.e., intra-seasonal to interannual variability, including weather events) occur and therefore affect their characteristics. DCV may also arise simply from the stochastic nature of these higher frequency variations. CLIVAR’s overarching aim for DCV is to observe and monitor these changes, to improve the overall physical and dynamical understanding of the underlying phenomena and mechanisms and their predictability and subsequently to predict their evolution, consequences and impacts.


Major research themes

The Research Focus identifies some broad objectives:

  • To study the space-time characteristics of observed decadal variability in the climate system as it is expressed in the interaction between its components and in relation to external forcing. Strive to attribute the observed variability to natural and anthropogenic forcing, including natural (solar variability and volcanic eruptions) and anthropogenic (changes in GHG, aerosol concentrations, and land use).
  • To study the space-time characteristics of DCV in climate models to determine these models’ capability to correctly capture the observed characteristics.
  • Apply models of various complexities and controlled experiments to study processes that lead to DCV either internally or in response to external forcing.Study the predictability of DCV in combination with and separately from anthropogenic or natural external forcing and test the ability to predict DCV using hindcasting of observed variability. Understand regional differences in decadal predictability and prediction capabilities.

The CLIVAR research themes are not exhaustive, thus are not limited to the subjects detailed here.

More information

Please refer to the DCVP Research Focus page for more detailed information. Any comments should be directed to Anna Pirani (

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Eastern boundary upwelling systems (EBUS)

Figure: Satellite remote sensing imagery of the central California Current upwelling system. (a) Sea surface temperature (SST) and (b) surface chlorophyll (Ryan et al. 2005).

Upwelling systems bring nutrient rich waters from the deep ocean to the surface. Areas of upwelling are often associated with highly productive oceanic regions, offering great economic value in terms of fisheries (see satellite image above showing surface chlorophyll concentrations off the west coast of America). Regions of upwelling are located in equatorial (Inter Tropical Convergence Zone, ITCZ) and coastal (eastern Pacific and Atlantic) regions of the ocean. Upwelling is driven by ocean surface winds. Consequently climatic events, causing shifts in prevailing winds (e.g. El Niño, the Indian Ocean Dipole and Tropical Atlantic Variability) can cause variations and reduction in the strength of upwelling systems. Present models of upwelling systems show large biases, impacting climate simulations. Consequently there is a need to identify the key physical processes that are responsible for upwelling and improving their representation in models. 


Major research themes
  • Identifying the key physical and biogeochemical processes and impacts on ecosystem dynamics in upwelling regions and improving their representation in models
  • Addressing upwelling related biases in climate models
  • Exploring how upwelling systems will respond to change in climate

The CLIVAR research themes are not exhaustive, thus are not limited to the subjects detailed here.

Please refer to the Upwelling RF page for more information. Any comments should be directed to Jing Li (


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Regional Sea Level Change and Coastal Impacts

Figure: Left, Time series of global mean sea level (deviation from the 1980-1999 mean) in the past and as projected for the future (Solomon et al. 2007); Right, Greenland ice sheet calving (NASA, Image credit: Ian Joughin, University of Washington)

Coastal SL rise is among the most severe societal consequences of anthropogenic climate change. Contemporary global mean sea level rise will continue over many centuries as a consequence of anthropogenic climate warming, with the detailed pace and final amount of rise depending substantially on future greenhouse gas emissions.

Over the coming decades, regional sea level changes and variability will significantly deviate from global mean values. The detailed sea level change along coastlines can therefore potentially be far more substantial than the global mean rise and will depend on many processes involving the ocean, the atmosphere, the geosphere and the cryosphere. Societal concerns about sea level rise originate from the potential impact of regional and coastal sea level change and associated changes in extremes on coastlines around the world, including potential shoreline recession, loss of coastal infrastructure, natural resources and biodiversity, and in the worst case, displacement of communities and migration of environmental refugees.


Research Focus Working Groups
  1. An integrated approach to historic sea level estimates (paleo time scale)
  2. Quantifying the contribution of land ice to near-future sea level rise
  3. Contemporary regional sea level variability and change
  4. Predictability of regional sea level
  5. Sea level science for coastal zone management

Please refer to the Regional Sea Level Change and Coastal Impacts RF page for more detailed information. Any comments should be directed to Lei Han (

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Understanding and predicting weather and climate extremes

Figure: Top. The positive and the negative phases of the North Atlantic Oscillation (Bojariu and Gimeno 2003); Bottom, Hurrell North Atlantic Oscillation (NAO) Index (Hurrell 2012).

Weather and climate extremes are an inherent part of climate. There is overwhelming evidence that the climate and its extremes are changing. As extremes affect every aspect of our society, decision- and policy makers, and stakeholders are increasingly asking for reliable predictions of extremes on time scales from days to seasons and centuries. To meet this societal need, the world climate research community is challenged by underlying science questions and the quality and coverage of the observational data that are used to monitor and understand extremes. Both the questions and the data need urgent attention in order to better identify the factors and mechanisms that determine the location, intensity, and frequency of various climate extremes including droughts, floods, heavy precipitation events, heat waves, cold spells, tropical and extratropical storms, coastal sea level surges and ocean waves. This information is needed in the near-term (from a season to a year) to mitigate risks to society and ecosystems, and in the longer term (from a decade to centuries) for effective adaptation planning. Despite the importance of the topic, progress has been fairly slow. However, recent developments suggest that the prospects for more rapid advancement of this WCRP Grand Challenge are excellent.


Major research themes
  • Identification of the key modes of ocean-atmosphere variability, impacting the magnitude and frequency extreme events, both now and in the future;
  • Increasing observational data sets, providing higher temporal and spatial resolution for ocean-atmosphere processes;
  • Model development, addressing observational based approaches, improving variability in ocean-atmosphere simulations relevant to extreme events;
  • Investigating the physical mechanisms leading to changes in high impact (societally relevant) weather and climate extreme events.

The CLIVAR research themes are not exhaustive, thus are not limited to the subjects detailed here.


Please refer to the WCRP Grande Challenge on Understanding and Predicting Weather and Climate Extremes for more detailed information. 

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ENSO in a changing climate

The El Niño–Southern Oscillation (ENSO) phenomenon is a naturally occurring climate fluctuation, which originates in the tropical Pacific region and affects ecosystems, agriculture, freshwater supplies, hurricanes and other severe weather events worldwide. Despite considerable progress in our understanding of the impact of climate change on many of the processes that contribute to ENSO variability, it is not yet possible to say whether ENSO activity will be enhanced or damped, or if the frequency or character of events will change in the coming decades. As changes in ENSO have the potential to be one of the largest manifestations of anthropogenic climate change, this status has profound impacts on the reliability of regional attribution of climate variability and change. 


Major research themes
  • Better understand the role of different physical processes that influence ENSO characteristics and the diversity of El Niño events on decadal time scales;
  • Understand how ENSO characteristics might be modified in the next decades, namely under the influence of anthropogenic climate change;
  • Propose a standard ENSO evaluation protocol for CGCMs.

Please refer to the ENSO in a changing climate RF page for more detailed information. Please note that this is an evolving document and is subject to updates and revisions. Any comments should be directed to Lei Han (

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Consistency between planetary energy balance and ocean heat storage (CONCEPT-HEAT)

Figure: Preliminary overview graphic summarizing the CLIVAR research opportunity “Consistency between planetary heat balance and ocean heat storage” (image credit, Karina von Schuckmann, University of Toulon, France)

Climate dynamics is very much about exchanges of energy in the Earth System, in particular in the form of heat. An ongoing accounting of where heat goes and its manifestations is a great need and has implications for interpreting the recent past and immediate future. Large uncertainties challenge our ability to infer these changes. Improving the accuracy of our estimates of Earth’s climate state and variability will improve knowledge and understanding of the climate system. This in turn will be translated into improved climate assessments and more reliable climate models, synthesizing the observations, performing attribution of what is happening and why, and in making predictions and projections on all space and time scales. 


Major research themes
  • Earth Observation Measurement Constraints on Ocean Heat Budget;
  • In situ observations of ocean heat content changes;
  • Ocean reanalysis for atmosphere-ocean heat exchange and ocean heat content estimate.

Please refer to the document of this CLIVAR Research Focus for more detailed information. Any comments should be directed to Nico Caltabiano (

Report of the CLIVAR-ESA Scientific Consultation Workshop on Ocean Heat Flux is now available for download. Presentations are also available online.


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AFP/GETTY (2013) The first rains of the monsoon season fall in India, Telegraph Media Group Ltd

Biswaranjan Rout/AP (2013) Pakistan floods: over a million homes destroyed after heavy monsoon rains, Telegraph Media Group Ltd

Villarini and Vecchi. (2012). Twenty-first-century projections of North Atlantic tropical storms from CMIP5 models. Nature Climate Change. doi:10.1038/nclima

Hurrell, James & National Center for Atmospheric Research Staff (Eds). Last modified 19 Oct 2012. "The Climate Data Guide: Hurrell North Atlantic Oscillation (NAO) Index (station-based)."

Joughlin, Last modified 29 November 2012, Disko Bay, Greenland. Accessed via NASA website.

Turner (2007) Indian Summer, Planet Earth Online, NERC

Roxana Bojariu, Luis Gimeno, Predictability and numerical modelling of the North Atlantic Oscillation, Earth-Science Reviews, Volume 63, Issues 1–2, October 2003, Pages 145-168, ISSN 0012-8252, 10.1016/S0012-8252(03)00036-9.

Ryan et al. (2005) Physical–biological coupling in Monterey Bay, California: topographic influences on phytoplankton ecology, Marine Ecology Process Series, 287:23-32).

Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.), (2007) Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.