Water, water everywhere, but not enough measurements

Professor Bjorn Stevens of the Max Planck Institute for Meteorology is among the chairs for the scene-setting stage of the Climate Symposium, taking place in Darmstadt in October 2014. His research focuses on the effect of clouds on the climate system, and he says one of the big challenges for climate science now, is to attract the next generation of brilliant minds with the unanswered questions of climate.

“It’s really important to communicate the fascinating scientific questions in our field. One of the problems is that we’ve been so busy communicating that we know the climate is warming, and why it’s warming, we sometimes make our field seem boring - like we already know the answers to the main questions.

“There are big scientific questions we haven’t answered, important ones about how the world works.”

Professor Stevens says the Grand Challenges Initiative can help scientists to explain what the big unanswered questions are to help attract new scientists into the field.

One of the most important topics that Bjorn Stevens would like to see get more attention is the role of water in the atmosphere.

Meteosat can show water vapour in the middle and upper tropospheres, but more measurements are needed in the lower troposphere.

Meteosat can show water vapour in the middle and upper tropospheres, but more measurements are needed in the lower troposphere.

“I don’t think anyone would disagree that understanding climate is first and foremost about understanding water in the atmosphere. Almost everything we understand about climate is about understanding water in the atmosphere and paradoxically, almost everything we don’t know is also linked to water in the atmosphere.

“We spend a lot of time dealing with secondary and tertiary elements of the climate system and sometimes we forget how important water is, and how poorly in some respects we measure it. ”

Space-based observations can help fill in some of the gaps that exist in our understanding of the atmosphere, but Professor Stevens says getting some measurements will be really tricky.

“Satellite observations are great because they give us a real picture – an actual image of what we are trying to explain. I work a lot with models, so it’s important to make contact with the real world. Data is what makes what we do science, after all.

“A lot of money has to go into space-borne measurements, and we should prioritise what we need to measure, rather than going after what we already know we are able to measure. And what we need to measure is really water, water, water.”

The Climate Symposium offers a good opportunity to prepare answers about future climate research priorities that aren’t really being asked yet, according to Professor Stevens.

“I think it’s a real opportunity if we as a community come together to remind ourselves what’s really important.

“Most of us in the scientific community think that CO2 is causing the world to warm. We normally explain the recent slower warming as natural variability in relation to a background warming trend. Most of us agree on this, and think before long we will see a very strong warming trend. At that point society will ask us what we are doing, and what kind of science countries should be investing in. We should be ready with good ideas.”

Infrared data over NASA's Blue Marble shows global cloud cover.

Infrared data over NASA's Blue Marble shows global cloud cover.

Although there are many unanswered questions, and a need for clear thought about climate science priorities, Professor Stevens says it is possible to solve some of the puzzles our atmosphere poses. In his own specific field involving the effects of clouds on the climate system, some of big questions are at last being answered.

“In Earth science, it is rare that we can answer a question once and for all. The question that we’ve been asking for 30 or 40 years is about how clouds amplify or damp the warming from CO2. I think we are getting close now in changing how we ask that question, which is about as close to a final answer as one can get. That’s exciting for me. We understand the processes.”

Bjorn Stevens will chair the session Setting the scene: Science perspective at the Climate Symposium. Full programme and details on the Climate Symposium website.