CMOS Bulletin SCMO
Vol. 45, No.2
15
50th Anniversary: Interviews
Q: How did this work inform your own research?
The paper showed clear trends in climate. This motivated the desire to understand the underlying causes of
the trend and has led to my many-year effort in the field of climate change detection and attribution.
Q: What are your research plans for the future?
My main research will focus on understanding the causes of observed changes in the climate as well as future
evolution of climate, in particular climate change at regional and local scale that is most relevant to
impacts.
Q: What do you see as some of the major issues associated with climate change?
There are many important issues the climate community faces. The World Climate Research Program has
identified important research areas as 7 Grand Challenges that require international partnership and
coordination and that yield “actionable information” for decision makers. These grand challenge projects
include melting ice and global consequences, clouds, circulation and climate sensitivity, carbon feedbacks in
the climate system, understanding and predicting weather and climate extremes, water for the food baskets of
the world, regional sea-level change and coastal impacts, and near-term climate prediction.
Q: Could you comment on which of these 7 Grand Challenges you see as particularly relevant within
the Canadian context?
This is indeed a bit too difficult to answer as these high priority areas are also related and linked. For example,
while climate extremes are very important to the impacts, understanding changes in extremes and providing
robust projection of future extremes do require improved models that have sufficiently accurate and realistic
cloud scheme and that simulate large scale circulation as well as its influence on surface climate well.
About Xuebin
Dr. Xuebin Zhang is a Senior Research Scientist with the Climate Research
Division, Environment and Climate Change Canada.
He served as lead authors for IPCC assessment reports. His current
research focuses on past and future changes in climate extremes.
Paper Summary
Temperature and Precipitation Trends in Canada during the 20
th
Century
: X. Zhang, L.A. Vincent, W.D.
Hogg and A. Niitsoo, 2000
This paper analyses trends in Canadian temperature and precipitation during the 20th century using, for the
first time, temperatures homogenized for site relocation and changes in observing programs, and
precipitations adjusted for known instrument changes and measurement program deficiencies. The data was
first interpolated to a 50 × 50 km grid to take into account the uneven distribution of the station data which is
sparse in northern Canada (north of 60°N). From 1950-1998, a distinct pattern of warming in the south and
west, and cooling in the northeast regions of the country was found in winter and spring. Across Canada,
precipitation increased by 5% to 35%, with significant negative trends in the southern regions during the
winter. The ratio of snowfall to total precipitation increased, with negative trends in southern regions during the
spring. The causes of the different spatial and temporal trends are not discussed here but there is some
evidence of agreement between the trends observed in Canadian climate and those predicted by the Global
Climate Models incorporating an increase in atmospheric greenhouse gases.
CMOS Bulletin SCMO
Vol. 45, No.2
16
50th Anniversary: Interviews
Interview with Nigel Roulet
Prof. Nigel Roulet is one of the authors on the 2000 paper
Parameterization of peatland hydraulic
properties for the Canadian Land Surface Scheme (CLASS)
. This was the first inclusion of organic matter into
a land surface package, providing a significant contribution to the field of climate modelling.
Q: What motivated you to pursue this area of research?
When I was working on my PhD on low arctic hydrology, the catchment I was working on had deposits of peat
in the valley bottoms. This completely altered the ‘typical’ permafrost hydrology we had expected from my
supervisor’s work in the high arctic. I soon realized that very few people had worked on peatland hydrology,
but peatlands were a very important land cover of Canada – 12% of Canada is covered with peat. So I then
began working on peatland hydrology and it became obvious that as the peat accumulated, it modified the
hydrology that allowed the peatlands to originally form. Fast forward 30 years, and we now know peatlands
are complex ecosystems that are self-regulating because of the negative feedbacks between the production of
peat and its accumulation and the hydrology of the peatland. This makes these ecosystems unique when
studying climate change because the self-regulation gives them a resilience in some cases. The motivation of
the work in the paper in Atmosphere-Ocean came from recognizing that peatlands contain about one third of
the world’s soil carbon and the maintenance of that vast store of carbon was dependent on the peatlands
remaining wet, and that climate change might lead to changes in wetness of peatlands. I thought it was fairly
important to try and get the properties of peat into the Canadian Land Surface Scheme (CLASS) since
peatlands were such an important land cover type. The first step of this process was to get the parameters for
peat and organic soil into the CLASS.
Q: What do you perceive was the main impact of this research?
Our research was the start, enabling climate modellers to get peatlands into climate models. This allows us to
now examine the sensitivity of the vast carbon stores in northern peatland to climate change. Based on that
work and our simulations we now know that bog like peatlands are not very sensitive to climate change but are
highly sensitive to land-use change that alters their hydrology. Once their hydrology is changed they become
more sensitive to changes in climate. The bog-like peatlands represent about 70% of northern peatlands in
Canada. Our modelling shows us that the fen-like peatlands are very sensitive to climate change and could
become net carbon sources to the atmosphere with climate change. We are still working on the size of this
feedback.
Q: How, since publication, has this research informed other research in this area, in Canada or around
the world?
The parameters synthesized in the paper have been incorporated into CLASS and are in all the subsequent
versions of CLASS, therefore they are in the Canadian climate and earth systems models. We first developed
Peatlands in the Hudson Bay Lowlands.
The eddy covariance tower at the Mer Bleue peatland,
Eastern Ontario – the longest running carbon observatory
for a peatland in the world.