It is said that a picture is worth a thousand words. In science communication however, a simple graph can be worth far more than pictures particularly when the main point is that the last four years have been the hottest on record.
In a press release the World Meteorological Organisation said,
‘The long-term warming trend has continued in 2018, with the average global temperature set to be the fourth highest on record. The 20 warmest years on record have been in the past 22 years, with the top four in the past four years.’
The main message was echoed by others, such as the BBC.
Climate change: Last four years are ‘world’s hottest’
Likewise the Guardian:
Past four years hottest on record, data shows
It all goes to show how temperature data can be misrepresented if you don’t show the temperature data itself.
Fig 1 is the HadCRUT4 monthly global temperature from the UK Met Office.
As you can see a graph tells a very different story. The past decade has a climate change contribution but what elevates the past four years above the previous ones is an El Nino event, the strongest one on record. As we have said many time before an El Nino is not a climatic phenomenon, it is weather. What’s more, after its peak in 2016 the global temperature has fallen by around 0.4° C. The past four years being the warmest on record is true, but it has been primarily due to the 2015/16 super El Nino.
Fig 2 shows the same data with error bars from which it can be seen that 2018 is statistically equivalent to some years before the El Nino event.
The WMO statement is grossly misleading. It mixes climate with weather. For example in its ‘Highlights of the provisional statement on the state of the climate,’ it states;
‘Temperatures: 2018 started with a weak La Niña event, which continued until March. By October, however, sea-surface temperatures in the eastern Tropical Pacific were showing signs of a return to El Niño conditions, although the atmosphere as yet shows little response. If El Niño develops, 2019 is likely to be warmer than 2018.’
If 2019 develops an El Nino and is warmer than 2018 then this has nothing to do with the ‘State of the Climate,’ but everything to do with annual weather variations.
It is sad to see the WMO descend into ‘Fake News’ territory, but sadder still to see science reporters regurgitating it without any form of analysis or critical thinking. A decade ago most financial journalists did the same. Thankfully many are much better now and they would never take an alarmist report from the Bank of England, for example, at face value without digging into the figures.