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Alberta Floods highlight a more active water cycle with climate change
An intense rainfall and storm event on June 20-21 has caused widespread flooding in the Canadian province of Alberta, encompassing much of the southern portion of the province including Canada's fourth largest city of Calgary. It is the worst flooding event in Alberta's recorded history, highlighting the more active hydrological cycle with climate change.
Over 120,000 people across the region were evacuated, 75,000 in Calgary (7% of the population), many now returning to flood damaged homes and businesses to start the clean up.
I am not going to say climate change caused the flooding. Clearly natural weather variability still plays a significant part in extreme weather events. But the reality is we have warmed the atmosphere and changed the base climate from which all extreme weather events are generated from. We are now living with weather in a more active hydrological cycle resulting in more frequent and intense storm events with a capacity to cause greater flooding.
Unusually wet spring, warm rain on snow, Intense rain from slow moving storms
An unusually wet spring provided soaking ground conditions with little extra capacity to absorb more rain. This is verified by two NASA satellites - the Gravity Recovery and Climate Experiment (GRACE) - which show that groundwater in the region has been at progressively higher levels than average – leaving the land with little extra capacity to take up additional water coming in from rainfall and melting snow, according to a Globe and Mail report.
“The role of groundwater is often overlooked, in particular when it comes to flooding and drought,” said Jay Famiglietti, a hydrologist at the University of California, Irvine, and a member of the GRACE science team. “If you pay attention to this type of this data … you can see that the flooding is inevitable. It is like a bucket filling up with water. It can only hold so much.”
Late snow melt also combined with warm rain on snow to accelerate melt-water flow into rivers.
Then a slow moving intense storm system with extremely heavy rainfall provided the immediate extreme weather trigger to produce the massive flooding.
Towns such as Banff and Canmore in the foothills of the Rocky mountains recorded more than 200 millimetres of rain on June 20, and had already received more than double their monthly average rainfall. Rivers rose dramatically and quickly, bursting banks and inundating the flood plains, and the roads, homes and businesses that have been built in low lying areas. (CTV News: Alberta under water: The 4 factors that led to massive flooding)
The flooding has been described as a 1 in 100 year event, but far surpassed the last 1-in-100 year flooding event in southern Alberta in 2005. On Monday Alberta's Premier Alison Redford announced a C$1billion initial recovery effort, but as Bloomberg reported, the total damage cost will far exceed this. The event has set new Canadian flood records with the damage expected to become Canada's costliest flood, with a record number of people forced to evacuate from their homes.
Canada's Carbon bomb: Alberta Tar Sands carbon emissions rising
Alberta is also where the tar sands are being mined, one of the dirtiest, carbon intensive, fossil fuel extractive industries, which is impacting and degrading the Boreal forest environment and the planetary climate. As well as the mining process degrading the Boreal forests of Alberta, Climate change is increasing Canada's Boreal forest mortality reducing carbon sink capacity. Scientists also warn that wildfires in Canada are approaching a threshold value where they may experience a rapid increase in size.
The carbon emissions from tar sands mining and processing operations contributes directly to climate change, represent 51% of the entire oil/gas sector in 2012, an increase from a share of only 20% in 2005.
A Greenpeace commissioned study by consultancy firm Ecofys released in January 2013 - Point of No Return (PDF) - showed that the Canadian tar sands were one of 14 giant fossil fuel projects which would produce 6.3 gigatonnes of CO2 a year by 2020. According to the report "production of oil from the tar sands in Alberta will triple from 1.5 to 4.5 million barrels a day by 2035, adding 706 million tonnes of CO2 to global emissions a year. By 2020, the tar sands expansion would add annual emissions of 420 million tonnes of CO2, equal to those of Saudi Arabia."
These fossil fuel 'carbon bombs' if allowed to continue will make limiting warming to the agreed 2 degrees Celsius almost impossible to achieve, pushing global warming to 4 to 6 degrees Celsius by the end of the century as projected by the the prestigious Postdam Institute for Climate Impact Research (PIK) for the World Bank in November 2012.
The intense storm and flood event are in a very real way, nature's blowback for intransigence on climate mitigation and playing with numbers by the Harper Federal Government and Alberta provincial Government to tackle Canada's carbon emissions.
Now nature has taken a swipe back at Alberta. As Canadian scientist and educator David Suzuki said in 2011 "We humans may be heavy hitters, but we must remember that nature bats last." Bloomberg reports the flooding has left downtown Calgary flooded empty and closed, and with three oil pipelines needing to close and a damage bill to homes and offices expected to reach C$5 billion.
Global Flood Risk is Increasing
Scientific research shows that Global flood risk is increasing under climate change. A paper published earlier this month - Global flood risk under climate change (Hirabayashi et al 2013) - detailed that a warmer climate would increase the risk of floods. Insurance company analysis of extreme events also shows the trend for flood risk increasing. Read more at Climate Central: As Calgary Floods, Scientists Warn of Rising Risks.
The southern Alberta flood event is not alone in experiencing devastating floods this month. Extensive flooding also occurred in Germany, and in northern India and Nepal unusually severe and early monsoonal rain caused extensive flooding, landslides with 1000 deaths reported and many people dislocated and needing evacuation.
In Australia we can sympathise with the flood victims in Alberta after the Torrential rain, tornados on Queensland coast caused extensive flooding in January 2013, and the devastating Queensland floods in 2011 - both categorised as 1 in 100 year events.
Flood adaptation and climate mitigation
So how do we respond to this increase in flood risk? We need to have adaptation strategies for the short and medium term and a climate change mitigation strategy for the long term, and we need to carry out both adaptation and mitigation strategies simultaneously.
For climate mitigation we need to reduce our consumption of fossil fuels and carbon emissions, particularly carbon emissions from intensive sources such as the Alberta tar sands. We have already changed the climate to alter the frequency and intensity of extreme weather events, and mitigation will help stabilise the future climate.
The Harper Government in Canada, and the Albertan provincial Government have encouraged the tar sands development and walked away from climate mitigation under the Kyoto Protocol with broad condemnation at home and abroad. The Climate Action Network International that attends all climate negotiations have given the Fossil of the Year Award, The Colossal Fossil, to Canada for the last 6 years for inaction and disruption throughout the UN climate talks.
For adaptation we need to reassess flood levels, flood risk, and flood zones for development. Once in a century events are more likely to become more frequent which will require land use floodmap rezoning, perhaps higher levees in places to protect vital infrastructure. If we don't address the primary cause of climate change we are left with increasing expensive damages and costs of adaptation.
During the peak of the flooding in Alberta the following interview was recorded which, I think, highlighted the relationship of climate change to the flood event.
CBC radio broadcaster Anna Maria Tremonti interviewed Bob Sandford on her program, the Current for Friday 21 June 2013. Bob Sandford is the chair of the Canadian Partnership Initiative of the United Nations Water for Life decade, and the author of Cold Matters: The State and Fate of Canada's Fresh Waters.
My transcription of this interview follows: