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Climate change: what we don’t know

by Judith Curry

This past week, there have been several essays and one debate that provide some good perspectives on what we don’t know about climate change, and whether we should be alarmed.

James Lovelock

Nature has an interview with James Lovelock:  James Lovelock reflects on Gaia’s legacy.  Excerpts:

The Revenge of Gaia was over the top, but we were all so taken in by the perfect correlation between temperature and CO2 in the ice-core analyses [from the ice-sheets of Greenland and Antarctica, studied since the 1980s]. You could draw a straight line relating temperature and CO2, and it was such a temptation for everyone to say, “Well, with CO2 rising we can say in such and such a year it will be this hot.” It was a mistake we all made.

But being an independent scientist, it is much easier to say you made a mistake than if you are a government department or an employee or anything like that.

In your latest book you advocate not trying to halt climate change but exercising what you call a sustainable retreat. Why is that?
I think it is the better approach. To rush ahead and advance is very much the Napoleonic approach to battle. It is far better to think about how we can protect ourselves. This is something we should be looking at carefully, not just applying guesswork and hoping for the best.

A lot of investment in green technology has been a giant scam, if well intentioned.

 What do you think of peer review — is it necessary?  For run-of-the-mill papers, say if somebody comes up with a really neat method for analysing some component of urine or that kind of thing, it is important to keep it. But not on larger topics.

 

Lennart Bengtsson

GWPF provides a translation of an essay by Lenaert Bengtsson entitled The science and politics of climate change.  Bengtsson was previously the Director of Research at ECMWF and Director of the Max Planck Insitute for Meteorology.  Excerpts from the essay:

The science isn’t settled and we still don’t know how best to solve the energy problems of our planet.

More CO2 in the atmosphere leads undoubtedly to a warming of the earth surface. However, the extent and speed of this warming are still uncertain, because we cannot yet separate well enough the greenhouse effect from other climate influences. Although the radiative forcing by greenhouse gases (including methane, nitrogen oxides and fluorocarbons) has increased by 2.5 watts per square meter since the mid-19th century, observations show only a moderate warming of 0.8 degrees Celsius. Thus, the warming is significantly smaller than predicted by most climate models. In addition, the warming in the last century was not uniform. Phases of manifest warming were followed by periods with no warming at all or even cooling.

The complex and only partially understood relationship between greenhouse gases and global warming leads to a political dilemma. We do not know when to expect a warming of 2 degrees Celsius.  In other words: global warming has not been a serious problem so far if we rely on observations. It is only a problem when we refer to climate simulations by computer models.

There is no alternative to such computer simulations if one wants to predict future developments. However, since there is no way to validate them, the forecasts are more a matter of faith than a fact. The IPCC has published its expert opinion a few months ago and presented it in the form of probabilities. As long as the results cannot be supported by validated models they produce a false impression of reliability.

It is no surprise that there are other forces that are driving rapid change. Because once government subsidies are involved, huge profits are available. However, before radical and hasty changes to the current energy system are implemented, there must be robust evidence that climate change is significantly detrimental. We are still far away from such evidence. It would be wrong to conclude from the report of the IPCC and similar reports that the science is settled.

iai TV debate

iai TV has a series Philosophy for our times: cutting edge debates.  Frankie May of iai TV pointed me to this debate between Bob Carter, Michael McIntyre and Richard Cornfeld entitled What we don’t know about CO2: The science of climate change.  My attention was piqued in particular by the participation of Michael McIntyre, who is likely to be the smartest guy in any room with climate scientists in it.  The blurb for the debate is :

There is no question that CO2 levels are increasing due to human activity. But predicting the impact of this is less straightforward. Will our understanding of the world’s climate system remain mired in complexity until it is too late? Or is apocalyptic thinking confusing the science?

I listened to whole thing (its about 15 minutes), it is superb.  There are many gems in this, from each of the 3 participants. At the end of this, I don’t see much dis agreement among the three participants. Some notes I took from listening to the debate.

We shouldn’t worry, we should just accept that this will happen and we should adapt to it and regard it as a business opportunity.

Its arrogant to assume that climate will remain static.

The whole language of climate change is designed to confuse the public and policy makers

Bob Carter says the IPCC has accomplished the inversion of the null hypothesis, where the onus is now on disproving dangerous anthropogenic climate change

We should focus on protecting people from natural hazards, and not worrying about what is causing them

It makes sense to encourage alternative energy and see what happens.

Bob Carter closed with this: no scientist can tell you whether it will be warmer or cooler in 2020, so we should prepare for both

JC reflections

It is gratifying to see leading scientists and thinkers ‘stepping off the reservation’ to provide interpretations of climate science and thoughts on how we should respond, that differ from the IPCC assessments and the more alarmist interpretations.

It is unfortunate that it seems to be primarily the independent scientists and retired scientists that are doing this; government employees in many countries would not do this (even if their personal convictions differ from the IPCC consensus), and the same seems to be true for most scientists employed by universities.  This is a very unhealthy situation particularly for universities.

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