Hans von Storch is a German climate scientists who believes global warming is real but now admits, in an interview with Der Spiegel, that climate models seem to have some problems.
Von Storch comes across as a moderate in the interview. He both embraces climate change as a reality and rejects the abuse of it to hector people in public pronouncements:
Storch: Unfortunately, some scientists behave like preachers, delivering sermons to people. What this approach ignores is the fact that there are many threats in our world that must be weighed against one another. If I’m driving my car and find myself speeding toward an obstacle, I can’t simple yank the wheel to the side without first checking to see if I’ll instead be driving straight into a crowd of people. Climate researchers cannot and should not take this process of weighing different factors out of the hands of politics and society.
A bit later in the interview, Der Spiegel asks him about the 15 year pause in warming which we are now experiencing. Von Storch admits the actual temperature increase has been very close to zero:
SPIEGEL: Just since the turn of the millennium, humanity has emitted another 400 billion metric tons of CO2 into the atmosphere, yet temperatures haven’t risen in nearly 15 years. What can explain this?
Storch: So far, no one has been able to provide a compelling answer to why climate change seems to be taking a break. We’re facing a puzzle. Recent CO2 emissions have actually risen even more steeply than we feared. As a result, according to most climate models, we should have seen temperatures rise by around 0.25 degrees Celsius (0.45 degrees Fahrenheit) over the past 10 years. That hasn’t happened. In fact, the increase over the last 15 years was just 0.06 degrees Celsius (0.11 degrees Fahrenheit) — a value very close to zero. This is a serious scientific problem that the Intergovernmental Panel on Climate Change (IPCC) will have to confront when it presents its next Assessment Report late next year.
SPIEGEL: Do the computer models with which physicists simulate the future climate ever show the sort of long standstill in temperature change that we’re observing right now?
Storch: Yes, but only extremely rarely. At my institute, we analyzed how often such a 15-year stagnation in global warming occurred in the simulations. The answer was: in under 2 percent of all the times we ran the simulation. In other words, over 98 percent of forecasts show CO2 emissions as high as we have had in recent years leading to more of a temperature increase.
Von Storch concludes that, at the outside, the models will have been proven wrong if the constant temperatures continue for another 5 years. This leads to the next question: What could be wrong with the models?
Storch: There are two conceivable explanations — and neither is
very pleasant for us. The first possibility is that less global warming
is occurring than expected because greenhouse gases, especially CO2,
have less of an effect than we have assumed. This wouldn’t mean that
there is no man-made greenhouse effect, but simply that our effect on
climate events is not as great as we have believed. The other
possibility is that, in our simulations, we have underestimated how much
the climate fluctuates owing to natural causes.
Despite his skepticism of the models, Von Storch still believes we will see a temperature increase of at least 2 degrees Celsius by the end of this century. He calls that his “instinct” though obviously it’s an informed instinct. Von Storch also had this comment about the process of climate science “Natural science is also a social process, and one far more influenced by
the spirit of the times than non-scientists can imagine.”