Back in 2016, the UK MET Office’s median projection to the start of 2021 forecast a global temperature temperature anomaly of 1.4C above their 1850-1900 “Pre-Industrial” baseline. Their recently published five year model projection (rightmost blue blob on graph), shows a 2021 median anomaly 0.35C lower, at 1.05C.

Their HADcruT 4GL temperature time series (data since 2016 added in red on graph) shows a linear trend of +0.09C/semi-decade for the last 50 years. CO2, by far the biggest forcing in their model, is still rising in lockstep with the 50 year temperature trend. What could have caused this remarkable downward step change in their model output?

Despite the fact the MET Office consumes vast sums of public money (a large chunk of it to pay for super-computers to run their models on), there is little transparency, so we’ll have to speculate with some informed guesswork. Here are a few possibilities.

1). The MET Office might have realised that since the high altitude water vapour feedback to increasing CO2 their model has previously relied on to project its worrying future trends hasn’t happened, they needed to remove or at least reparameterise it in their model input.

Fig 2. Specific humidity at various atmospheric pressures

Specific humidity at 300mb (just below the tropopause) has actually been falling, not rising, since around 1960. This is because its level isn’t a feedback to CO2 at all, but to solar activity, as I discovered 10 years ago.

Fig 3. Specific humidity vs Sunspot number.

2) Maybe The MET Office has realised that solar activity levels have a much bigger effect on global temperature than they previously thought. It’s becoming clear that the Sun has played the principle role in climate change. Back in 2007, I pioneered a technique for relating solar activity to ocean heat content, and thus sea surface temperature (SST). Using an empirical method to determine the monthly sunspot number (SSN) at which the high heat capacity oceans neither gained nor lost energy, I integrated the solar data using this value as the departure point and found a good correlation with global temperature change over the C20th. The same technique was later used by a talkshop contributor to correlate the reconstructed Solar TSI integral with Michael Mann’s 2008 reconstruction of global temperature since 1200AD.

Fig 4. Global temperature VS Total Solar Irradiance integral

Looking at the new projection from the MET Office, it’s clear that their model predicts that there is going to be a very large El Nino event peak by Christmas next year. But then, their previous five year model projection predicted a similarly high peak, potentially breaching the much hyped “1.5C above pre-industrial” in late 2018, which failed to materialise. If that damp squib was due to the reduction in solar activity, maybe the MET Office should start taking more notice of the solar prediction made by the Talkshop team’s Rick Salvador in 2013, because if it’s correct, cycle 25 will be exceptionally low.

It’s always possible we’ll get a big El Nino as often happens when solar activity is low. The big El Nino’s of 1988, 1998 and 2010 all occurred soon after solar minimum, and the Sun is remaining persistently inactive at the moment. Here’s the latest from

Fig 6. Solar activity remains very low in 2021. Monthly SSN is around 16.

If there is a big El Nino event, I suspect that it will be followed by a big drop in global temperature. The Sun’s output has been below the level that maintains ocean heat content for a lot of the C21st, and that will start to have an effect soon, as excess energy built up during the high solar cycles of the later C20th dissipates.

Don’t sell your coat.

via Tallbloke’s Talkshop

February 3, 2021 at 04:42AM