Earlier this year CSIRO Atmospheric Research released a report
Climate Change under Enhanced Greenhouse Conditions in Northern
interviewed one of the authors, Senior Research Scientist
Dr Kevin Walsh
Is there a connection between the high temperatures around the
world at the moment (see graph) and climate change?
This graph from NOAA illustrates how July 1998 was the warmest
month worldwide in the historical record. Printed with permission
of the National Oceanic and Atmospheric Administration (NOAA)
It's been in the news that July 1998 was the warmest month
worldwide in the historical record. I think it's fair to say that
we haven't detected an unambiguous human contribution to this trend
but on the other hand if Greenhouse gases were causing the world to
warm then this is exactly the sort of effect you might expect.
But can you say that the longer term temperature rises we've seen
are due to Greenhouse gases and not just natural variation ó
such as more radiation from the sun?
Several studies have come out recently which have reinforced the
conclusion that it is at least partly due to Greenhouse gases.
How can they tell?
Firstly, Greenhouse gases produce a characteristic warming across
the globe—more at poles than at the equator—and
secondly Greenhouse gases warm more in the upper troposphere than
lower troposphere (the troposphere is the 8km thick layer of
constantly moving air closest to the earth). These telltale warming
patterns have indeed been detected.
Is there a link with the flooding here and overseas?
The thing about the impact of flooding is that it is so dependent
on climate variability from year to year and human trends like
population increases in flood-prone areas. The jury is still out on
links to climate change.
Moving on to the North Australia Study, what aspects of climate
change are important up here?
In north Australia the variation in rainfall is the important
So what are your predictions for the changes in rainfall in the
We had great difficulty in coming up with predictions for summer
rainfall in the north that's linked to ENSO (El Nino Southern
Oscillation) variations. We don't know what's going to happen to
ENSO under climate change. The latest models give us different
results for rainfall change than the earlier models ó
unusually the Australian region is the only major region in the
world where this is true.
Because our rainfall is dependent upon sea surface temperatures in
the Pacific, and those in turn are related to ocean circulation
changes which we don't have a really good understanding of yet.
Can you say something about expected changes in rainfall intensity?
One of the things that we suggested might occur would be increased
intensity of rainfall events in the north Australian summer.
What about the dry-season winter rainfall?
That's interesting because for winter rainfall the older models and
newer models agree for northern Australia and predict slightly less
rain in the future.
Is there a link between climate change and the record wet seasons
and "wet" dry seasons that parts of the north have been getting
It's difficult to make extrapolations for a long forecast from just
the past few years. Again it is a question of local effects being
influenced by year-to-year changes in climate rather than long-term
ones, so I don't know if you should read too much into that at the
Anything you want to add to finish up?
I think it's important to realise that some climate change is now
inevitable. Even if we stopped producing Greenhouse gases tomorrow
the oceans' temperature are still adjusting to the Greenhouse gases
that have already been put into the atmosphere so that will keep on
warming into the middle of next century.
Interview Peter Jacklyn
For a special north Australian forecast go to the Savanna Links
Australian Department of Climate Change
The website of the Australian Greenhouse Office
CSIRO Marine and Atmospheric Research
DPIF Climate Services
This web site provides seasonal forecasts and for climate outlooks for Queensland, as well as more general information about climate and weather
National Oceanic and Atmospheric Administration
SILO: Agricultural and Meterological Information
The SILO web site provides climate outlook information across Australia. Some services are provided on a user-pays basis.