Source: BBC TV News
URL: N/A
Date: 23/09/2013
Event: Andrew Montford on the "pause": "If they can't explain it then they should say so"
Attribution: BBC TV News, also thanks to Geoff Chambers for transcribing this
People:
Fiona Bruce: The most recent international report on climate change due later this week is expected to confirm that human activity is primarily responsible for global warming - that's meant warmer oceans, melting snow and ice, and a rise in sea levels. In the last hundred years there's been an increase in global average temperatures of 0.8° Celsius and further rises are projected. But what's baffling scientists is that for the last fifteen years temperatures haven't gone above the level recorded in 1998. Here's our science editor, David Shukman.
David Shukman: The air we breathe is changing. It now holds more of the warming gas carbon dioxide than at any time in human history. And new records of temperature keep being set. Crops burned last year in America’s hottest month ever. In China this summer people were desperate to keep cool in heat that no-one had experienced. So, how much is the planet warming? Well, in this graph, the red area shows computer simulations of the global average temperature. The white line is what's actually been recorded. Temperatures rising recently, until fifteen years ago, for some reason, they paused.
Myles Allen: Decade on decade, global warming is proceeding as expected. That said, within the past fifteen years, we've seen little warming at the surface, and that in itself is enough to tell us that the most extreme projections of warming over the next twenty or thirty years are looking less likely, and that's clearly good news.
David Shukman: One explanation is that the sun is giving off less heat. Another is that industrial pollution is reflecting the sun's rays. A third idea is that the oceans are warming. Scientists have a network of devices that are measuring a rise in water temperatures.
Brian King: The deep ocean has without doubt warmed up since the nineteen eighties, but the ocean is so vast, that even a hundredth of a degree temperature change is significant in terms of the impact that that will have on the atmosphere above it.
David Shukman: So there are several theories for why the warming of the planet has paused. The most plausible answer for many scientists does lie in the oceans with all of the different currents. But so far, the evidence from the deep is still pretty sparse, so at this stage no-one can be really sure. One blogger read by thousands every day has long raised questions about the pause. Andrew Montford accepts mankind is affecting the climate, but says there's so much the scientists don't know.
Andrew Montford: If they can't explain it then they should say so. And people will learn from that that there's a lot about the climate system that scientists don't understand. That's the truth, and that's what the public needs to know.
David Shukman: A major report on climate change is due on Friday. The scientists will try to explain why temperatures have paused, while insisting that global warming in the long term remains a dangerous threat. David Shukman, BBC News.