A climate model for every season

(Another group with an apparent variation on this third version of the story recently published in the Proceedings of the National Academy of Sciences.)

All these different stories add up to another, bigger problem for global warmers. For they would also seem to cut across the other answer often given to that tricky question of what is natural and what is not - that the carbon models give such good fit for the past few decades of warming (excluding the decade just gone) that industrial emissions must be to blame for that warming. To reinforce the point about the models scientists point out that they include all the factors known to be involved in climate variations - sunlight, aerosols etc - and none of those explain the warming. Unfortunately for that line of reasoning, and in another sharp blow for the CO2 models, recent research has confirmed a growing suspicion that scientists do not yet know all the major factors at work in climate.

In a recent paper in Nature Geoscience three American scientists admit that they cannot work out what happened at the Palaeocene-Eocene Thermal Maximum (about 55 million years ago), when a lot of carbon got dumped into the atmosphere and temperatures rose 5-9C in a few thousand years. The scientists conclude that the existing carbon models are of no use in explaining what went on.

The paper’s abstract says:

At accepted values for the climate sensitivity to a doubling of the atmospheric CO2 concentration, this rise in CO2 can explain only between 1 and 3.5 °C of the warming inferred from proxy records. We conclude that in addition to direct CO2 forcing, other processes and/or feedbacks that are hitherto unknown must have caused a substantial portion of the warming during the Palaeocene-Eocene Thermal Maximum. Once these processes have been identified, their potential effect on future climate change needs to be taken into account.

And that is just one of a series of complete failures for the carbon-based models in modelling any of earth’s known pre-historic climate. See the New Scientist article: “Once the South Pole was green”.

In other words, just to underline the point, scientists really have no idea what drives climate. They don’t really know why the earth flips in and out of ice ages (much of the theory concerning Milankovich cycles was recently overturned), or why the current interglacial period has been much longer than any of the others, or why the medieval warming period or little ice age occurred.

Something is missing; what is it? There have been a few suggestions, including Senator Fielding’s “flares”, but they are all still a matter of intense debate. One promising addition to the research in this area is a recent paper from researchers at the National Centre for Atmospheric Research, or NCAR in the US, headed by Gerald Meehl. The researchers claim to have identified a new mechanism by which quite small changes in the sun’s energy output can interact with climate cycles to have a major effect on earth’s climate. The formal paper in the journal Science is here. A more general explanation is here. The paper is about the mechanism - an interaction between the sun, the stratosphere and the oceans - rather than any forecast but, of course, if the mechanism is used to make a successful forecast then it will be streets ahead of any other theory in this field, including the CO2 based models.