Real Global Temperature Trend, p15 – 2016-2020 global forecast: 5-year average temperatures above 2015 record, despite La Niña

It’s raining climate records since late 2014. That has increased to a proper storm from October 2015 – the first month to show global temperature anomalies of more than 1 degree above the 1951-1980 climate average (so higher still above pre-industrial(!)). And if April 2016 too will have an average global temperature deviation of at least about 0.9 degrees above 1951-1980 climate average (and it will likely be higher) then the world will have had 12 consecutive monthly temperature records.

Take a minute to think about how insane that really is: Each and every month breaking the monthly temperature record in a data range that goes back to at least 1880. So much for ‘natural climate variations,’ right?

2014 was the then-hottest on record, which was broken by 2015. And despite the fact that La Niña conditions are developing and East-Pacific (see graph below) ocean temperature anomalies already peaked in November 2015 – our guess is that 2016 will break 2015′s global temperature record.

La Niña forecast 2016 - IRI ensemble graph
According to IRI’s ensemble graph the world will transition from (strong) El Niño to (strong) La Niña conditions over the coming months of 2016. NASA GMAO & Scripps model runs indicate a shaken scenario, with ENSO neutral state around May – and strong La Niña conditions from and throughout the autumn of 2016.

The first three months of 2016 where the three hottests months on record, globally – and we think even the above-developing La Niña cannot compensate for that: 2016 will become the hottest year on record. But of course from there on everyone’s wondering how the global climate will recover from the 2015 El Niño and when and how we will be able to observe the ENSO-neutral temperature trend emerging.

Well, the people at the UK Met Office’s Hadley Centre have got news – bad news.

They used the CIMP5 climate model (the upgraded IPCC model – a standard) to predict the net global temperature effects for the next five year period (2016-2020) following from continued rise in atmospheric CO2 and modelled fluctuations in ocean currents, like the El Niño/La Niña Southern Oscillation (ENSO) and the Atlantic Meridional Overturning Circulation (AMOC).

Their model runs confirm the ‘scientific gut-feeling’ of many: The temperature record of 2015 isn’t a real ‘peak’, but rather a large-scale correction of the ’1998-2013 temperature plateau’ – one that opened up room for the underlying temperature trend to emerge.

To be a bit more concrete: the researchers forecast that global average temperatures will not dip or plateau, but rather surpass those of the 2015 record – as shown in their global temperature forecast graph below:

Global temperature forecast graph: trend goes up! - Hadley Centre
Sneak peak into the future: the trend goes up – the 5-year average of 2016-2020 will likely be higher than the 2015 temperature record, according to the UK Met Office. The black line represents observed temperatures from combined Hadley Centre, NASA and NOAA datasets – blue range is forecast temperatures according to CIMP5 run (including a modelled La Niña dip for 2016-2017 – well done there CIMP5!).

Elevation of global temperatures between 2016-2020 above the 2015 record tells us something about the height of the 5/10-year observational temperature trend line, the one that should be more or less ENSO neutral.

If this trend line would indeed be above the 2015 record than it is higher than some might have thought – which would support recent findings about CO2 climate sensitivity (also being higher than previously assumed).

It is however still not the trend line we are looking for in our series. We want to find the ‘really-real trend line’ – that is the temperature trend if you would correct for thermal inertia and important masking factors like global dimming – that is the temperature value that tells us something about the actual equilibrium temperature that is coupled to the exact amount of CO2 we have pumped into the atmosphere at any given time, the inevitable future warming we are responsible for.

We will get to exactly that temperature here at Bits of Science, soon. Stay tuned!

© Rolf Schuttenhelm | www.bitsofscience.org

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