New view on climate

The climate change debate is becoming too polarised on atmospheric temperature rises which are difficult to measure and quantify – instead we should be looking at global ‘total energy’ content, writes Clive Simpson.

Stephen Briggs, chairman of the Global Climate Observing System (GCOS) steering committee, warned on Friday that there needs to be a “paradigm shift” in how we are looking at out planet.

“The focus on rising temperatures has bit us in the back and is probably a lousy indication of climate change in the first place,” he said.

“The fundamental drivers of climate change are heat in the system not the remote thermal trace in our atmosphere.”

Dr Briggs was speaking at the joint ESA and UK Space Agency (UKSA) conference ‘Space: the new view on climate change’ in London on Friday.

The event focused on climate change monitoring by satellites and the achievements of ESA’s Climate Change Initiative (CCI).

Measurements from satellites flying above Earth now provide essential information on the effects of climate change on our planet.

Since its launch in 2010, ESA’s CryoSat spacecraft has been monitoring changes in the ice sheets that blanket Greenland and Antarctica.

Scientists from the UK’s Centre for Polar Observation and Modelling have used CryoSat data to show the Antarctic ice sheet is now losing 159 billion tonnes of ice each year – twice as much as when it was last surveyed.

This ice loss contributes to rising sea levels – one of the many and potentially most devastating effects of climate change.

Sea-surface temperature is another crucial factor – and satellites indicate that a warming trend lasting three decades has slowed within the last 15 years.

Scientists speculate that one of the causes of this ‘plateau’ in sea-surface temperature could be a change in the exchange of ocean water between warm, surface waters and cold, deep waters below 700 m – as if the warming is ‘hiding’ deep down.

Christopher Merchant from the University of Reading showed how satellites studies indicated overall heat content of the oceans could continue to rise without sea surface temperatures going up.

He said changing wind patterns had affected ocean currents in the western Pacific and likely caused an up-welling of water at the equator.

“Deeper water also tends to be cooler and surface warmth is therefore being buried deeper in ocean,” he explained.

“This is a complex picture and we have number of mechanisms that are likely to play some role. Satellite data is helping is understand the proportional effect these are likely to have in future.”

Volker Liebig, director of ESA’s Earth observation programme, stressed the need for continued measurements from satellites for environmental and climate research.

“Using these scientific observations of climate is fundamental for making policies,” he said. “Political attention is important to this subject – but political action is most important.”

CCI is the world’s largest coordinated programme for providing data on key climate parameters to support the analysis of climate change from space.

The UK is involved in both the running of the programme – which is done from the ESA Climate Office, based at ESA’s European Centre for Space Applications and Telecommunications at Harwell, Oxford – and the scientific aspects of CCI.

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