Category Archives: visualisation

Climate indicators

The recent IPCC AR6 WGI report summarises the state of knowledge of physical climate science, but the final version of the Summary for Policymakers (SPM) did not include a figure showing a range of indicators of our warming planet.

An earlier draft of the SPM included a figure like that below which aimed to put recent changes into a longer context of changes over the past 2000 years, and to show how other climate metrics have changed in recent decades. Many of these time series were shown in disparate places of the report, and have been brought together in this updated graphic which also indicates key milestones and discoveries in climate science.

Indicators (from top to bottom): atmospheric carbon dioxide concentration, ocean heat content, global sea level, global mean surface temperature, global lower tropospheric temperatures, Arctic sea ice amount, Kyoto cherry blossom date, specific humidity over land. Key moments in the history of climate science are indicated: the invention of the efficient steam engine by James Watt in 1790, the identification of the primary greenhouse gases by John Tyndall in 1861, the first estimate of climate sensitivity by Svante Arrhenius in 1896, and the discovery that the world was warming by Guy Callendar in 1938.

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Adding observations to IPCC figures

The figures in the IPCC AR6 WGI SPM are a huge improvement over previous reports. However, one minor quibble is with the lack of observations shown. This brief post makes a figure available which is based on IPCC AR6 WGI SPM Figure 8, but with some observations added to show how global surface temperature and Arctic sea ice area have varied, compared to the model simulations. In my view this is a scientific improvement over the original version.
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IPCC SPM Figures

The Working Group I (WGI) component of the IPCC 6th Assessment Report (AR6) has been released. One key development since AR5 was the involvement of professional graphic designers in creating the figures for the Summary for Policymakers (SPM). As a result, the graphics are clear and usable, having been user-tested through several design iterations. The data underlying the figures are also openly available.
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Glimpsing the future

In December 2019, the average temperature across Australia was about 2°C above what would be expected for the present-day, which is another 1.5°C above temperatures that were normal for December before humans started warming the climate. These extreme temperatures have contributed to the catastrophic bushfires which have devastated large areas.

But what may be considered ‘normal’ is constantly changing.

In a world which has warmed by 3°C – roughly the current global trajectory – what was extreme will be entirely normal.

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Atmospheric temperature trends

The lower atmosphere is warming while the upper atmosphere is cooling – a clear fingerprint of the enhanced greenhouse effect from human emissions of carbon dioxide.

The simple explanation is that some of the infrared radiation emitted by the surface, which would have normally reached the upper atmosphere, is absorbed by greenhouse gases in the lower atmosphere. The upper atmosphere therefore receives less energy than before, and so cools. The very warm years (intense reds) in the upper atmosphere are the 1982-83 El Chichón and 1991-92 Pinatubo eruptions respectively.

Changes in global atmospheric temperature at different levels in the atmosphere from 1979 to 2018: surface, TLT, TTT, TMT, TLS. Data from Cowtan & Way, and RSSv4. The colour scale goes from -0.75K to +0.75K, relative to the average of 1981-2010 for each layer separately.


On 21st June 2019, the #ShowYourStripes initiative was launched, providing ‘warming stripe’ graphics for virtually every country at

The data was provided by Berkeley Earth and several national meteorological agencies, and the stripe graphics are available for 1901-2018 for most locations, but extended further backwards where the national data was easily available. The US States and UK regions have their own separate graphics, as do Stockholm, Oxford and Vienna – three of the longest continuous series in Europe.

Over 1 million graphics have been downloaded from the website, and many media outlets covered the story: BBC, Washington Post, Fast Company and Gizmodo. Continue reading #ShowYourStripes