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About the Climate change projections

The probabilistic climate change projections are the result of an innovative modelling approach from the Met Office Hadley Centre climate model HadCM3. The model is one of the few examples using perturbed physics ensembles (PPE) to generate climate projections. The projections also include the results of other IPCC climate models, and are constrained by observations of past climate. Further details on the methodology are in Chapter 1, Chapter 2 and Chapter 3 of the Climate change projections report. Use the links below to go to:

They provide projections of climate change, and absolute future climate for:

  • Benefits
  • They assign probabilities to different future climate outcomes. 
  • They reflect uncertainties within the Met Office Hadley Centre's global climate model, including the most important known climate feedback processes.
  • They include information from other global climate models
  • The output can be used in different ways.
    The UKCP09 User Interface allows the probabilistic projections to be visualised and interrogated to produce images (e.g. maps and graphs) or download the data as numerical outputs. Output for several variables and temporal-average periods is available. See the UKCP09 User Interface .
  • They are available for 25 km grid squares and for pre-defined aggregated areas.
    Aggregated area projections are provided for administrative regions and river basins. Probabilistic projections over the oceans around the UK are provided for a number of marine regions.
  • They use the longest set of RCM runs ever produced for the UK to date.

More about the benefits...

  • Main assumptions
  • That known sources of uncertainty not included in UKCP09 are not likely to contribute much extra uncertainty.
  • That structural uncertainty across the current state of the art models is a good proxy for structural error.
  • That models that simulate recent climate, and its recent trends well, are more accurate at simulating future climate.
  • That single results from other global climate models are equally credible. 
  • That projected changes in climate are equally probable across a given 30 year time period.
  • That local carbon cycle feedbacks are small compared to the impact of the carbon cycle via change in global temperature.

More about the assumptions

  • What should I be aware of?
  • The probabilities reflect the strength of evidence supporting the projection.
  • Emissions uncertainty is not addressed using probabilities.
  • Downscaling method does not incorporate information from other regional climate models.
  • No information in form of daily or hourly time series.
  • Variables that don't produce robust probabilities are not included in the projections.

More about what to be aware of...

  • Uncertainties
  • Modelling uncertainty - arising from incomplete understanding of the climate system, and our inability to model it perfectly.
  • Natural climate variability - arising from both internal and external factors on the climate system.
  • Emissions uncertainty - arising from not knowing the amount of future global greenhouse gas emissions.
  • Contributions to uncertainty from downscaling.

More about uncertainties...