'There could be conflicts and wars'

People all over the world are trying to protect themselves against the consequences of climate change – often with some counter-productive effects. Measures that should keep climate change in check can also end up as maladjustments, even if they are not explicitly named in the UNEP Frontiers Report 18/19. An interview with Ulrike Niemeier, a scientist at the Max Planck Institute for Meteorology, on just how sensible such activities are.

Dr. Niemeier, a number of more or less well-intended measures in the battle against global warming could actually backfire. Is geoengineering one of these?

Yes, you could say that.

Just what is geoengineering?

The term is used to describe a number of different methods. On the one hand, you could remove CO₂ from the atmosphere. This is referred to as carbon dioxide removal. The second method is so-called solar radiation management, where solar radiation is artificially reduced. I work in the second field. A number of years ago, we began to simulate the effects of volcanoes on the climate using climate models. Sulphur is released into the stratosphere when a volcano erupts. A similar situation, but man-made, is being discussed as a geoengineering technique.

With what effect?

The sulphur, or rather the resulting sulphate particles, reflects sunlight. This means that less sunlight reaches the earth’s surface, which would therefore cool down.

Like keeping the climate under control synthetically?

Yes. The effects can be more or less assessed in model simulations. We have not discovered any side effects in the results. Our models have shown that temperatures in the year 2070 would be more pleasant with geoengineering – but only if carbon dioxide emissions are not reduced, in other words compared to the expected effects of climate change.

And no alarming disadvantages?

On the contrary. We know that there would be less global precipitation on average. This could lead to bigger droughts or to a worsening of existing droughts. Of course, other weather extremes such a flooding could still occur. This is a risk that is very hard to handle politically.

In what respect?

For example, a group of countries could get together and say: we are going to do this. But then, an uninvolved country that suddenly suffers an exceptional drought could sue the other countries. Or even worse: it could lead to conflicts or wars. You cannot limit the effects of the measure to only your own territory. Sulphur spreads through the stratosphere and the layer of sulphur covers the entire earth. Consequently, the effects are always global.

It sounds as if things could escalate quite quickly.

Precisely. Which is why we are now looking into the matter scientifically, so that politics keeps away from it. Now and in the future. What’s more, such measures could lead to a decline in political efforts to reduce CO₂ emissions. And that would be absolutely counter-productive.

The interview was conducted by Klaus Wilhelm