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Plume plots in detail

This page gives more information about when it is appropriate to use plume plots, some things to be aware of when using them and details about how uncertainties are reflected in the plume plots.

What should I use them for?


Plume plots are useful to explore and to display climate projection information in certain circumstances. You might like to use them:

  • To indicate how projected climate changes evolve through time

Plume plots are the only product available through the UKCP09  User Interface that shows projected climate changes for all seven 30 year time periods simultaneously. This makes them a useful way of showing how climate change is projected to evolve through time.

The plume plots show the change associated with five probability levels (10%, 33%, 50, 67% and 90%). This means that plume plots also usefully show how the amount of uncertainty (the difference between the 10% and 90% probability lines) changes through time.

  • To identify by what time period a certain amount of climate change is projected to occur

Plume plots might also be useful to help identify when climate change is projected to become a problem for a given organisation or sector. If climate vulnerabilities or thresholds are known, it is possible to use a plume plot to explore when these are likely to be exceeded.

If you use plume plots in this way it is important to consider what the acceptable level of risk is for you or your organisation. For example, it might be the case that, based on the evidence, there is:

- a 10% chance of a threshold being exceeded by the 2020s,

- a 50% chance of the same threshold being exceeded by the 2040s, and

- a 90% chance of the same threshold being exceeded by the 2050s.

The point at which this change is perceived as a problem depends on attitude towards risk.

Things to be aware of


When using plume plots it is important to remember that they reflect the probability (for climate projections) or frequency distribution (for sea level projections) ranges obtained using the UKCP09 method. The range of projections contained in a plume plot captures the important known uncertainties associated with climate projections.

Other factors to bear in mind when using plume plots include:

· Plume plots summarise projected climate changes associated with seven 30-year time periods.

The plume plots show climate projections for the 2020s (2010-2030), 2030s (2020-2040), 2040s (2030-2050), 2050s (2040-2060), 2060s (2050-2070) 2070s (2060-2080) and 2080s (2070-2090). This means the information presented shows multiple time-averaged projections, and does not represent continuous (or transient) model output through time.

If continuous (transient) information is required, the 11-member RCM output, available through the Climate Impacts LINK project on the  BADC website , is the most appropriate tool to use.

Uncertainties

Plume plots of climate projections capture the important known modelling uncertainties and natural climate variability as reflected by the UKCP09 projections.

As a general guideline we suggest that the 10% to 90% probability level range should be used, as outside of this range the robustness of the probabilistic projections decreases.

Plume plots of sea level projections show frequency distributions which capture some important known modelling uncertainties (those associated with differences between IPCC global climate models).

For all plume plots, emissions uncertainty is explored through the use of three sets of climate projections to reflect three different scenarios of future greenhouse gas emissions:

  • Low emissions (IPCC SRES: B1)
  • Medium emissions (IPCC SRES: A1B)
  • High emissions (IPCC SRES: A1FI)

A single plume plot shows projections associated with a single, user-specified, emissions scenario. Multiple plume plots are therefore needed to illustrate emissions uncertainty.

For more information see the Handling Uncertainty page.