Category Archives: visualisation

New viridis colour scale

Below is a simple example of using different colour maps to show the same UK mean temperature data for both normal vision and a simulation of colour blindness.

Viridis is a new colour map developed for Python (MATLAB code here) with lots of nice features, including removal of artificial perceptual boundaries which jet suffers from.

Which do you prefer?

UK mean temperature, shown for four different colour scales, for both normal vision (top) and a red-green colour blind simulation (bottom).
UK mean temperature, shown for four different colour scales, for both normal vision (top) and a red-green colour blind simulation (bottom).

[This post continues our #endrainbow campaign to reduce use of ‘rainbow’ colour scales like jet.]

Reinventing the colour wheel

Between 5-10% of men and around 0.5% of women are affected by various forms of colour blindness. The most common form is deuteranopia, for which distinguishing between red and green is particularly challenging. This has been pointed out many times before, but it may be worth remembering next time you make a figure or visualisation: ‘red and green should never be seen’.

[Part of the #endrainbow campaign.]

Colour wheel for normal and simulated deuteranopic vision. Click for larger version.
Colour wheel for normal and simulated deuteranopic vision. Click for larger version.

When will we reach 2°C?

A change in global surface temperature to 2°C above pre-industrial climate is often used as a threshold for ‘dangerous climate change’. Although impacts will tend to get worse as temperatures increase, there is no clear evidence yet of such a sharp threshold in the climate. However, the 2°C threshold seems to be useful to policymakers. So, when might we expect to reach this threshold and have any regions experienced such a change already? Continue reading When will we reach 2°C?

The cascade of uncertainty in climate projections

Climate projections have demonstrated the need to adapt to a changing climate, but have been less helpful (so far) in guiding how to effectively adapt. Part of the reason is the ‘cascade of uncertainty’ going from assumptions about future global emissions of greenhouse gases to what that means for the climate to real decisions on a local scale. Each of the steps in the process contains uncertainty, but which step is the most important? And, how might this be visualised? Continue reading The cascade of uncertainty in climate projections

Sources of uncertainty in CMIP5 projections

The recent IPCC AR5 includes a discussion on the sources of uncertainty in climate projections (Fig. 11.8, section 11.3.1.1), which updates previous analyses using CMIP3 (temperature, precipitation) to the latest CMIP5 simulations. The dominant source of uncertainty depends on lead time, variable and spatial scale. Continue reading Sources of uncertainty in CMIP5 projections

Near-term regional climate: the range of possibilities

What are the possible regional temperature trends over the coming few decades? Globally, on average, there is expected to be a long-term warming, but this is not necessarily true for any particular location or period. What are the probabilities of a local warming or cooling? Continue reading Near-term regional climate: the range of possibilities

Recent slowdown in global surface temperature rise

The Science Media Centre recently held a briefing for journalists on the recent slowdown in global surface temperature rise, and published an accompanying briefing note. The Met Office also released three reports on the topic.

The key points were: (1) recent changes need to be put in longer term context & other climate indicators such as sea level, Arctic sea ice, snow cover, glacier melt etc are also important; (2) the explanation for recent slowdown is partly additional ocean heat uptake & partly negative trends in natural radiative forcing (due to solar changes and small volcanic eruptions) which slightly counteract the positive forcing from GHGs; (3) the quantification of the relative magnitude of these causes is still work in progress; (4) climate models simulate similar pauses. Continue reading Recent slowdown in global surface temperature rise