Wednesday, June 26, 2013

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.

Watch the youtube video of Canada Calgary Aerial View with Bob Sandford interview as the voiceover. The original audio podcast is by cbcradio.

My transcription of this interview follows:

    AMT: Good morning. Well what do you make of what we are seeing across southern Alberta this morning?

    BS: Well, to scientists working in the domain of climate effects on water this is really the worst of all possible outcomes. We built on flood plains because we thought we had relatively stable climate, the climate we have experienced over the past century. We thought it would stay the same. We also thought that we had a good grasp of how variable we could expect climatic conditions to be based upon what we had experienced in the past century. Now we have discovered that neither assumption was correct. We do not have adequate means to protect development on the flood plains, climatic conditions are more variable than we thought, and that variability is increasing as climate changes. We have also discovered that our hydrological conditions are changing.

    AMT: What do floods like this tell us about what is happening with our water cycle?

    If we put all the data together, they tell us that warming temperatures are altering the form water takes and where it goes in the hydrosphere. Evidence that increasing temperatures are accelerating the manner and rate of which water is moving through the hydrological cycle is now widely enough available to allow us to connect the dots with respect to what is happening in Canada.

    So let us start very briefly in the Canadian Arctic. In the north and throughout much of the Canadian Boreal water that has been trapped as ice in the form of glaciers and as permanent snow pack and permafrost is in decline. The same sort of thing is visibly evident in Canada's western mountains. There is now evidence we have lost as many as 300 glaciers in the Canadian Rockies alone between 1920 and 2005. The same thing that is causing our glaciers to disappear is in combination with landscape change, changing precipitation patterns on the great plains. The same warming is causing water left on the land after the last glaciation in the Great Lakes region to evaporate.

    So, you might ask where all this water is going? One of the places it is going is into the atmosphere where it becomes available to fuel more frequent and intense extreme weather events, such as the one you had in Toronto in 2005 that caused $700million flood damage to infrastructure, roads and homes. You may remember in that year that Calgary just dodged the same bullet. Well, not this time.

    What we are seeing here is that rising temperatures and the increasing concentration of atmospheric vapour are making what were once predictable natural events much worse. What we discovered is the atmosphere holds about 7 per cent more water vapour for each degree Celsius temperature increase. What this tells us is the old math and old methods of flood prediction and protection won't work any more. Until we find a new way of substantiating appropriate action in the absence of this hydrological stability, flood risks is going to be increasingly difficult to predict or price, not just in Calgary or Canmore, but everywhere.

    AMT: So you are saying then there is more condensation in the air, the warm air can hang on to water then burst when it hits somewhere and it can no longer hang on to it?

    A Warmer atmosphere is more turbulent and carries more water vapour. We are seeing that happening widely. We are also seeing in North America disruption in the jet-stream which is allowing climatic events to cluster and remain in places for longer periods of time, resulting in more intense floods and droughts. We are seeing this as part of a general warming of the atmosphere.

    AMT: You've said this is because of climate change. How do we know this isn't a fluke, just an outlier?

    We know that Clausius–Clapeyron relation is one of the standard algorithms that we use in climate science. And we know that as temperature increases we know what to expect in terms of water vapour increases in the atmosphere. We are beginning to see some very interesting phenomena associated with this. Things like atmospheric rivers, great courses of water vapour aloft that can carry between 7 and 15 times the daily flow of the Mississippi. When these touch ground or are confronted by cooler temperatures that water precipitates out and what we see are huge storms of long duration and the potential for much greater flooding events.

    AMT: So what you are saying is this is part of a broader pattern across North America?

    Well unfortunately this may be the new normal. I regret to say that everything we know about how climate effect the hydrological cycle suggests that events like this are likely to be more common. The insurance industry has already warned us of a trend towards more intense and of longer duration storms that cause more damage especially in areas of population concentration. This is certainly what we are seeing in the Calgary area.

    AMT: What are you hearing from people you know in Canmore?

    There is a great deal of concern about how long this event is going to last. We heard from residents there on your show there is a deep concern with how much damage has been done to very expensive infrastructure - roads and bridges. We are going to have to wait until the storm is over to determine exactly the extent of those damages.

    AMT: What should we be doing to address the situation you are describing?

    I think it is important to recognise that the laws of hydrological stability is a societal game changer, already causing a great deal of human misery widely. So we are going to have to replace vulnerable infrastructure across the country with new systems designed to handle greater extremes. This is going to be very costly. We are also going to have to invest more in science so we can improve our flood predictions.

    AMT: As you look at what is unfolding across southern Alberta, not surprising to you? Surprising? The residents say it was completely unexpected.

    I don't know if it was entirely unexpected. We know there is great variability in our climate naturally, and we also know that some of these influences are affecting the frequency of these storms events. Researchers at University of Saskatchewan have predicted already that events of this sort will be more common. No one likes to be right on such matters, but it appears that these are going to be events we are going to see more frequently in the future.

    AMT: That is a rather grim forecast, no pun intended.

    It is grim, but I think that if we accept what we see is happening right in front of our very eyes is real, then we can begin to adapt, begin to rethink about how we situate our homes, our infrastructure on flood plains. We can think about how we are going to adapt to more extreme weather events. It is not certainly outside the domain of human possibility to do so and we should be acting toward that direction.

Source attribution:

No comments:

Post a Comment