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Australia set to get more extremely hot days -

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ELEANOR HALL: There's more evidence that Australia is getting hotter.

Research from the Bureau of Meteorology shows that in the past 50 years, Australia's had two to
three times more record high temperatures than low ones and the scientist who did the research says
there are more extremely hot days to come.

The Bureau's Dr Blair Trewin spoke to George Roberts.

GEORGE ROBERTS: While both high temperature records and low temperature records continue to be set
in Australia, we've seen over the last 50 years high records have increasingly outnumbered low
records and over the last 10-12 years, high temperature records have been broken at a rate two to
three times higher than low temperature records are.

BLAIR TREWIN: What does this say for climate change research?

GEORGE ROBERTS: Well, it's consistent with a lot of other information we have. We know there's been
consistent warming trend in average temperatures in Australia over that time period. We know that
there's been an increase in the number of days over 35 degrees, a decrease in the number of nights
below zero in those places that get as cold as that.

So the findings we've made with respect to temperature records are consistent with all of those
other pieces of information.

BLAIR TREWIN: How did you actually come up with these figures?

GEORGE ROBERTS: Well, what we did was we took data from 68 locations spread around Australia.

We selected locations with best long-term records over that time and also the most consistent
records - data sets - over that time because there are some places where perhaps the site has
moved, or it's been influenced by urban development and you might get misleading results from
those.

BLAIR TREWIN: Climate change sceptics often cite that as an argument against the accuracy of this
kind of research.

How can you guarantee that this data is accurate and isn't comparing oranges with apples?

GEORGE ROBERTS: Yeah, well that's something we put a lot of effort into. And we do things like we
look at historical files, see how the local environment around a site has changed.

So we do take those types of influences into fairly careful account and in this study we made sure
that we eliminated any locations that we believed were suffering from some of those issues that had
been raised about a particular location.

BLAIR TREWIN: What does this say then to the so-called climate change sceptics who say that the
planet's actually been cooling over the past decade or so?

GEORGE ROBERTS: Well, a decade's a very short period of time to be looking at and in the case of
global temperatures 1998 was a massive El Nino year and if you're only taking trends over 10 years
one outlying year like that can really influence your results.

But once you go out to 40, 50, 100 years, trends become much less sensitive to the start and end
point.

BLAIR TREWIN: So you expect that the further you extend this study out, there'll be more record
highs coming through?

GEORGE ROBERTS: Yep, we expect that both we'd be bringing it up to date just with the last couple
of years of information and also into the future we expect to see average temperatures continue to
warm and with that we would expect to see a continued trend towards more high extremes and fewer
cold extremes.

ELEANOR HALL: That's the Weather Bureau's Dr Blair Trewin speaking to George Roberts.