Source: BBC Radio 4: Today Programme
URL: N/A
Date: 10/07/2015
Event: Richard Allan: "heating of the planet is going on, full pelt"
Credit: BBC Radio 4
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Justin Webb: Now, has global warming paused? There is a view, of course, that it has, during the first decade or so of this century. There didn't seem to be any measurable increase in global temperatures, in spite of of all the carbon we continue to release into the atmosphere. Climate scientists found the pause difficult to explain, but a paper published by ocean scientists at NASA seems to come up with an answer. Richard Allan is Professor of Climate Science at the Department of Meteorology at the University of Reading and is on the line - good morning.
Richard Allan: Good morning.
Justin Webb: And the answer is what?
Richard Allan: Well, I mean this new research shows that heating of the planet is going on, full pelt. Um, heat is continuing to build up in the oceans but in the last decade it's been penetrating a bit deeper down, so rather than heating up the surface layers, it's been going to deeper levels. So we've seen a slight suppression of the rate of global surface temperature rise, in the last decade.
Justin Webb: So what we were - what will surprise you, or interest you, is where it is gone - the fact that it is there, that this extra heat is somewhere inside the atmosphere won't surprise you at all.
Richard Allan: Well, it's, it's gone into the ocean, so almost all the energy that's building up from the rise in greenhouse gases ends up in the ocean, because if you, if you imagine boiling up your pan of vegetables, it takes a lot of heat to warm the temperature up. So the oceans have a huge capacity for taking up heat, so it really matters where the heat goes.
Justin Webb: And does this study show absolutely conclusively, in your view, that that is the case?
Richard Allan: Well, this study adds to a bunch of other studies, including work at University of Reading and also with NASA, that heat is continuing to build up, and other studies have shown that the heat has gone a bit deeper down. We kind of know this about the ocean, because simulations that are used to make climate projections include the oceans, which slosh about, from decade to decade.
Justin Webb: So this tells us, does it - just to get this absolutely straight, from your point of view as a climate scientist, there has not been a pause in global warming in the early years of this century. That, in your view, is a fact.
Richard Allan: There's not been a pause in the heating of the planet. There's been a slight suppression in the rate of surface temperature rise, but -
Justin Webb: But wholly explicable.
Richard Allan: Yeah, wholly explicable, and we can expect a return to rapid surface temperature rise over the coming decades, in line with what we expect from the rise in greenhouse gases.
Justin Webb: Well yeah, when you say we can "expect" it, I mean, is there any sense - do these studies, does this NASA study and others, suggest what the process is, and how that process would be reversed, and how the heat would come to the surface?
Richard Allan: Well, we understand it from simulations, but also these observations, how the ocean sloshes about - it's like weather in the atmosphere, except it works on a much slower time scale, so from one decade to the next decade you get movement and circulation of the oceans. So we know that some decades temperature rise is suppressed a bit, other decades we get it amplified by the natural processes, and we can expect, over the long term, that the rising greenhouse gases will heat up the planet, so we need to - um, you know, this suggests it's of utmost importance to come to a global agreement on reducing human emissions of greenhouse gases.
Justin Webb: Yeah, and of course those talks in Paris in December, hugely significant and this will doubtless feed into those. Richard Allan, Professor Richard Allan from Reading University, thanks.