Drought – worse than we thought

Inconsistencies with drought models that don’t account for sea surface temperature changes mean that drought in a climate changed world could be worse than predicted.

WHO: Aiguo Dai, National Center for Atmospheric Research, Boulder, Colorado, USA

WHAT: Looking at the impact of sea surface temperature variability on drought

WHEN: January 2013

WHERE: Nature Climate Change, Vol. 3, No. 1, January 2013

TITLE: Increasing drought under global warming in observations and models (open access)

Climate deniers love it when the models are slightly wrong for predicting future climate changes, and believe me, I’d love it if climate change weren’t so verifiably real and we could all retire and live la dolce vita.

However, that’s not reality, and in the case of this paper, where the model doesn’t quite line up with the observed changes that’s because it’s worse than we previously though. Oh dear.

Global warming since the 1980s has contributed to an 8% increase in drought-ridden areas in the 2000s. It’s led to things like diminished corn crops and the steady draining of underground water aquifers in the USA, much of which is currently experiencing persistent drought. The letter L on the map below stands for long term drought.

Long term drought in the Southwest of the USA (from US Drought Monitor)

Long term drought in the Southwest of the USA (from US Drought Monitor)

What’s that got to do with climate models? Well, while the droughts in Southern Europe or my homeland of Australia are due to lack of rain drying things out, drought can also be from increased evaporation from warmer air temperatures, which the models don’t fully take into account.

These droughts are harder to measure because they’re related to sea surface temperature changes that take decades and can be hard to identify as a human forced signal rather than just natural variations. So this researcher compared sea surface temperatures with drought predictions and observed warming to try and work out what is going on.

Predicted changes in soil moisture globally for 1980–2080 (black dots are where 9 out of 11 models agree on data) (from paper)

Predicted changes in soil moisture globally for 1980–2080 (black dots are where 9 out of 11 models agree on data) (from paper)

There were two areas where the models differed from the observed changes – the Sahel area in Africa and the USA.

In the Sahel, the models predicted there would be warming in the North Atlantic Ocean which would lead to increased rain. What actually happened was that there was large warming in the South Atlantic Ocean compared to the North Atlantic and steady warming over the Indian Ocean which meant less rain, not more. Similarly, for the predicted patterns in the USA, the influence of the Pacific Multidecadal Oscillation was not known to be influenced by human climate forcing. However, it switched to a warm phase from above-normal sea surface temperature.

Top: Observed sea surface temperatures. Bottom: predicted sea surface temperatures (from paper)

Top: Observed sea surface temperatures. Bottom: predicted sea surface temperatures (from paper)

These sea surface variations that were missed in some of the previous models have some obvious consequences for planning for the slow pressure cooker of stress that drought is on anyone living through it, let alone trying to make a living from agriculture.

The researcher noted that there were also some differences from the models when looking at sulphate aerosols, however for the 21st Century the signal from greenhouse gases will be much stronger than those from aerosols, so shouldn’t mess with the data too much.

So what does this all mean? Well, it means that there are both regional and broader trends for drought in a changed climate. The broad patterns are fairly stable ‘because of the large forced trend compared with natural variations’, which is scientist for humans are making a large enough mess out of this to see the evidence clearly.

The paper ends quite bluntly stating that having re-worked the simulations to take into account the new data for sea surface temperature and other variables, that it’s only more bad news.

It’s likely to be ‘severe drought conditions by the late half of this century over many densely populated areas such as Europe, the eastern USA, southeast Asia and Brazil. This dire prediction could have devastating impacts on a large number of the population if the model’s regional predictions turn out to be true.’

Yes, a researcher actually used the word ‘dire’ in a scientific paper. Oh, and this was with an intermediate emissions scenario, not the business as usual path we’re currently all on. How about we all agree to stop burning carbon now?

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Much ado about phosphorus

‘Life can multiply until all the phosphorus has gone and then there is an inexorable halt which nothing can prevent’ – Isaac Asimov, 1974

WHO: K. Ashley, D. Mavinic, Department of Civil Engineering, Faculty of Applied Science, University of British Columbia, Vancouver, BC, Canada
D. Cordell, Institute for Sustainable Futures, University of Technology, Sydney, Australia

WHAT: A brief history of phosphorus use by humans and ideas on how we can prevent the global food security risk of ‘Peak Phosphorus’

WHEN: 8 April 2011

WHERE: Chemosphere Vol. 84 (2011) 737–746

TITLE: A brief history of phosphorus: From the philosopher’s stone to nutrient recovery and reuse (subs req.)

Phosphorus can be found on the right hand side of your periodic table on the second row down underneath Nitrogen. It’s one of those funny elements that we all need to live and survive and grow things, but is also highly reactive, very explosive and toxic.

It’s in our DNA – in the AGCT bases that connect to form the double helix structure of DNA, the sides of the ladder are held together by phosphodiester bonds. Phosphorus is literally helping to hold us together.

Phosphodiester bonds in DNA (from Introduction to DNA structure, Richard B. Hallick, U Arizona)

Phosphodiester bonds in DNA (from Introduction to DNA structure, Richard B. Hallick, U Arizona)

Phosphorus can be pretty easily extracted from human urine, which was what German alchemist Henning Brandt did in the 1660s in an attempt to create the Philosopher’s Stone which would be able to turn base metals into gold. No seriously, apparently he was committed enough to the idea to distill 50 buckets of his own pee to do this!

What do alchemy, DNA, and human pee have to do with a scientific paper? Well these researchers were looking at how we’ve previously used phosphorus, why it is that we’re now running out of it and what we can learn from history to try and avoid a global food security risk.

Phosphorus comes in three forms – white, black and red. The phosphorus that is mined for fertilizer today is apatite rock containing P2O5 and has generally taken 10 – 15million years to form. However, in traditional short term human thinking, the fact that it takes that long for the rocks to form didn’t stop people from mining it and thinking it was an ‘endless’ resource (just like oil, coal, forests, oceans etc.).

The paper states that originally, phosphorus was used for ‘highly questionable medicinal purposes’ and then doesn’t detail what kinds of whacky things it was used for (boo!). Given the properties of white phosphorus; it’s highly reactive and flammable when exposed to the air, can spontaneously combust and is poisonous to humans, the mind boggles as to what ‘medicinal’ uses phosphorus had.

The major use of phosphorus is as an agricultural fertilizer, which used to be achieved through the recycling of human waste and sewage pre-industrialisation. However, with 2.5million people living in Victorian-era London, the problems of excess human waste become unmanageable and led to all kinds of nasty things like cholera and the ‘Great Stink’ of the Thames in 1858 that was so bad that it shut down Parliament.

This led to what was called the ‘Sanitary Revolution’ aka the invention of flush toilets and plumbing on a large scale. This fundamentally changed the phosphorus cycle – from a closed loop of localised use and reuse to a more linear system as the waste was taken further away.

After the Second World War, the use of mined mineral phosphorus really took off – the use of phosphorus as a fertilizer rose six fold between 1950-2000 – and modern agricultural processes are now dependent on phosphorus based fertilizers. This has led to major phosphorus leakage into waterways and oceans from agricultural runoff creating eutrophication and ocean deadzones from excess phosphorus.

Eutrophication in the sea of Azov, south of the Ukraine  (SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE)

Eutrophication in the sea of Azov, south of the Ukraine
(SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE)

The problem here is, that we’ve switched from a closed loop system where the waste from the farm house goes into the farm yard and all the phosphorus can recycle, to a linear system where the phosphorus gets mined, used as fertilizer and much of it runs off into the ocean. It’s not even a very efficient system – only a fifth of the phosphorus mined for food production actually ends up in the food we eat.

The problem that we’re now facing is the long term ramifications of this new system where phosphorus has become a scarce global resource and we’ve now been forced to start mining the rocks that have lower quality phosphorus with higher rates of contaminants and are more difficult to access. We’re down to the tar sands equivalent of minable phosphorus, most of which is found in only five countries; Morocco, China, the USA, Jordan and South Africa. Maybe they can be the next OPEC cartel for phosphorus?

Peak phosphorus is likely to happen somewhere between 2030 and 2040, which is where the scary link to climate change comes in. The researchers cheerfully call phosphorus shortages the ‘companion show-stopper to climate change’, by which they mean that soils will start to run out of the nutrients they need at about the same time that extended droughts from climate change will be diminishing crop yields and we’ll have about 9 billion people to scramble to feed.

Basically, a phosphorus shortage is something that we can easily avoid through better and more efficient nutrient recycling, but it’s something that will kick us in the ass once we’re already struggling to deal with the consequences of climate change. The paper states that we need to start re-thinking our ‘western style’ of sewage treatment to better recover water, heat, energy, carbon, nitrogen and phosphorus from our waste systems. This doesn’t mean (thankfully) having to return to a middle ages style of living – it means having cities that are innovative enough about their municipal systems (I was surprised to find out that sewage treatment is one of the most expensive and energy intensive parts of public infrastructure).

The False Creek Neighbourhood Energy Utility in Vancouver

The False Creek Neighbourhood Energy Utility in Vancouver

In Vancouver, we’re already starting to do that with the waste cogeneration system at Science World and the False Creek Neighbourhood Energy Utility that produces energy from sewer heat.

It’s pretty logical; we need to re-close the loop on phosphorus use and we need to do it sensibly before our failure to stop burning carbon means ‘Peak Phosphorus’ becomes the straw that breaks the camel’s proverbial back.

Sleepwalking off a Cliff: Can we Avoid Global Collapse?

‘Without significant pressure from the public demanding action, we fear there is little chance of changing course fast enough to forestall disaster’
Drs. Paul and Anne Ehrlich

WHO: Paul R. Ehrlich, Anne H. Ehrlich, Department of Biology, Stanford University, California, USA

WHAT: An ‘invited perspective’ from the Royal Society of London for Improving Natural Knowledge (the Royal Society) on the future of humanity following the election of Dr. Paul Ehrlich to the fellowship of the Royal Society.

WHEN: 26 January 2013

WHERE: Proceedings of the Royal Society, Biological Sciences (Proc. R. Soc. B) 280, January 2013

TITLE: Can a collapse of global civilization be avoided?

Dr. Paul Ehrlich has been warning humanity about the dangers of exceeding the planet’s carrying capacity for decades. He first wrote about the dangers of over-population in his 1968 book The Population Bomb, and now following his appointment to the fellowship of the Royal Society, he and his wife have written what I can only describe as a broad and sweeping essay on the challenges that currently face humanity (which you should all click the link and read as well).

When you think about it, we’re living in a very unique period of time. We are at the beginning of the next mass extinction on this planet, which is something that only happens every couple of hundred million years. And since humans are the driving force of this extinction, we are also in control of how far we let it go. So the question is, will we save ourselves, or will we sleepwalk off the cliff?

Drs. Ehrlich describe the multiple pressures currently facing the planet and its inhabitants as a perfect storm of challenges. Not only is there the overarching threat multiplier of climate change, which will make all of our existing problems harder to deal with, we have concurrent challenges facing us through the loss of ecosystem services and biodiversity from mass extinction, land degradation, the global spread of toxic chemicals, ocean acidification, infectious diseases and antibiotic resistance, resource depletion (especially ground water) and subsequent resource conflicts.

you have humans Wow. That’s quite the laundry list of problems we’ve got. Of course, all these issues interact not only with the biosphere; they interact with human socio-economic systems, including overpopulation, overconsumption and current unequal global economic system.

If you haven’t heard the term ‘carrying capacity’ before, it’s the limit any system has before things start going wrong – for instance if you put 10 people in a 4 person hot tub, it will start to overflow, because you’ve exceeded its carrying capacity.

The bad news is we’ve exceeded the planet’s carrying capacity. For the planet to sustainably house the current 7 billion people it has, we would need an extra half an empty planet to provide for everyone. If we wanted all 7 billion of us to over-consume at the living standards of the USA, we would need between 4 – 5 extra empty planets to provide for everyone. Better get searching NASA!

The Andromeda Galaxy (photo: ESA/NASA/JPL-Caltech/NHSC)

The Andromeda Galaxy (photo: ESA/NASA/JPL-Caltech/NHSC)

The next problem is that a global collapse could be triggered by any one of the above issues, with cascading effects, although Drs. Ehrlich think the biggest key will be feeding everyone (which I’ve written about before), because the social unrest triggered by mass famine would make dealing with all the other problems almost impossible.

So what do we need to do? We need to restructure our energy sources and remove fossil fuel use from agriculture, although Drs. Ehrlich do point out that peaking fossil fuel use by 2020 and halving it by 2050 will be difficult. There’s also the issue that it’s really ethically difficult to knowingly continue to run a lethal yet profitable business, hence the highly funded climate denial campaigns to try and keep the party running for Big Oil a little longer, which will get in the way of change.

The global spread of toxic compounds can only be managed and minimised as best we can, similarly, we don’t have many answers for the spread of infectious and tropical diseases along with increasing antibiotic resistance that will happen with climate change.

Helpfully, Drs. Ehrlich point out that the fastest way to cause a global collapse would be to have any kind of nuclear conflict, even one they refer to as a ‘regional conflict’ like India and Pakistan. But even without nuclear warfare (which I hope is unlikely!) 6 metres of sea level rise would displace around 400 million people.

One of the most important things that we can be doing right now to help humanity survive for a bit longer on this planet is population control. We need less people on this planet (and not just because I dislike screaming children in cafes and on airplanes), and Drs. Ehrlich think that instead of asking ‘how can we feed 9.6 billion people in 2050’ scientists should be asking ‘how can we humanely make sure it’s only 8.6 billion people in 2050’?

How can we do that? Firstly, we need to push back against what they refer to as the ‘endarkenment’, which is the rise of religious fundamentalism that rejects enlightenment ideas like freedom of thought, democracy, separation of church and state, and basing beliefs on empirical evidence, which leads to climate change denialism, failure to act on biodiversity loss and opposition to the use of contraceptives.

And why do we need to push back against people who refuse to base their beliefs on empirical evidence? Because the fastest and easiest way to control population growth is female emancipation. Drs. Ehrlich point out that giving women everywhere full rights, education and opportunities as well as giving everyone on the planet access to safe contraception and abortion is the best way to control population growth (you know, letting people choose whether they’d like children).

More importantly, Drs. Ehrlich want the world to develop a new way of thinking systematically about things, which they’ve called ‘foresight intelligence’. Since it’s rare that societies manage to mobilise around slow threats rather than immediate threats, there need to be new ways and mechanisms for greater cooperation between people, because we are not going to succeed as a species if we don’t work together.

They’d like to see the development of steady-state economics which would destroy the ‘fables such as ‘technological innovation will save us’’. They’d like to see natural scientists working together with social scientists to look at the dynamics of social movements, sustainability and equality and to scale up the places where that kind of work is already happening.

They point out that our current methods of governance are inadequate to meet the challenges we face and that we need to work with developing nations who are currently looking to reproduce the western nation’s ‘success’ of industrialisation, so that they can instead be leaders to the new economy, because playing catch up will lead to global collapse.

Do Drs. Ehrlich believe that we can avoid a global collapse of civilisation? They think we still can, but only if we get fully into gear and work together now, because unless we restructure our way of doing things, nature will do it for us. It’s your call humanity – shall we get going, or will we sleepwalk our species off the cliff?

Don’t go in the Water

Warming sea surface temperatures in low-salinity oceans like the Baltic Sea is increasing cases of Vibrio bacteria infections

WHO: Craig Baker-Austin, Nick G. H. Taylor, Rachel Hartnell, Centre for Environment Fisheries and Aquaculture Science, Weymouth, Dorset, UK,
Joaquin A. Trinanes, Laboratory of Systems, Technological Research Institute, Universidad de Santiago de Compostela, Spain, National Oceanic and Atmospheric Administration, National Environmental Satellite Data and Information Service, CoastWatch, Maryland, USA
Anja Siitonen, Bacteriology Unit, National Institute for Health and Welfare (THL), Helsinki, Finland
Jaime Martinez-Urtaza  Instituto de Acuicultura, Universidad de Santiago de Compostela, Spain

WHAT: Establishing patterns between Vibrio bacteria infection outbreaks and climate change in the Baltic Sea to be able to predict future outbreaks.

WHEN: January 2013

WHERE: Nature Climate Change, Vol 3, January 2013

TITLE: Emerging Vibrio risk at high latitudes in response to ocean warming (subs. req)

Imagine that it’s a hot summer’s day in Northern Europe. The heat wave has lasted for more than three weeks now and you’re just dying to get into the ocean for a swim to cool off, except that you can’t, because there’s been a bacteria outbreak in the water and going swimming will make you sick.

Looks great! Can’t swim. (photo: flickr)

Looks great! Can’t swim. (photo: flickr)

It doesn’t sound like fun does it? But it’s happening increasingly in the Baltic Sea, and it looks like climate change is providing the exact conditions these bacteria love.

Vibrio is a type of bacteria that grows really well in warm (>15oC) low-salinity (<25 parts per trillion salt) water. The most common type in estuaries and other shallow water is Vibrio vulnificus, which is related to the same bacteria that causes cholera (Vibrio cholerae). Not a nice family, really.

When you swim in water that has Vibrio bacteria, it immediately gets excited (yes, I’m aware that bacteria don’t have feelings) about any cuts or wounds you have and infects them giving you symptoms like vomiting, diarrhea, abdominal pains and blistering dermatitis. Well, that’s a way to really ruin your summer.

If you’re really unlucky or immuno-compromised, Vibrio will give you blistering skin lesions, septic shock (life threatening low blood pressure) and possibly kill you 25% of the time. It’s an efficient bacterium though, and will kill you in only 48hrs.

Vibrio vulnificus (Wikimedia commons)

Vibrio vulnificus (Wikimedia commons)

So why is Vibrio moving into the Baltic Sea more often? Climate change, combined with location.

The Baltic Sea is the largest low-salinity marine ecosystem on Earth, and is surrounded by highly populated countries, meaning there are 30million people living within 50km of the shores of the sea. The Baltic Sea is also warming rapidly.

The Baltic Sea (Google maps)

The Baltic Sea (Google maps)

The researchers found that the sea surface temperature has been warming in excess of 1oC per decade, which is seven times the global average rate of warming. The rate is also increasing. From 1850 to 2010, the rate of warming was .51oC per century. The warming between 1900 to 2010 was at a rate of .77oC per century, and more recently the warming from 1980-2010 has been at a pace of 5oC per century, which is scarily fast for planetary systems.

Their data shows that for every 1oC increase in the summer maximum sea surface temperature, the rate of observed Vibrio infections increased by almost 2 times. This of course, gets compounded with the fact that increased summer maximum sea surface temperatures mean the air temperature is also hotter, and a hotter summer means more people head to the beach and get infected.

Even worse, recent research shows that some Vibrio bacteria’s ‘pathogenic competence’ (which is scientist for how good it is at infecting you) could be improved by increased temperatures.

Which all adds up to a nasty sequence of events where many more people than usual get nasty skin lesions. So what should we do about it? The researchers suggest monitoring conditions and sending out health advisories for when the sea surface temperatures are >19oC for three weeks or more as well as using predictive models to try and work out where/when the worst outbreaks might occur.

I don’t know about you, but nasty bacterial infections from a warmer ocean on a slowly cooking planet doesn’t sound like a good idea to me. So I’d also like to suggest we stop burning carbon so I and the people of Northern Europe can continue to swim in the summer.

Hot Enough Yet? Warming in Western North America

How much and in what ways has the western part of North America warmed from climate change between 1950 and 2005?

WHO: Evan L. J. Booth, James M. Byrne and Dan L. Johnson, Water and Environmental Sciences, University of Lethbridge, Alberta, Canada

WHAT: Collating all of the weather station data from North America west of the Mississippi River and looking at the long term trends.

WHEN: 13 December 2012

WHERE: International Journal of Climatology (Int. J. Climatol.) Vol. 32, Issue 15 (2012)

TITLE: Climatic changes in western North America, 1950–2005

As we all know, climate change is a global problem with regionally specific impacts. How the climate changes will depend on what your local climate was originally like. So how much has the western end of North America changed from 1950 to 2005? That’s what these researchers in Alberta set out to discover.

Firstly, for this research paper their area of western North America is more than just the Pacific Northwest. They decided to go with everything west of the Mississippi River in the USA and everything west of Manitoba in Canada, which is pretty diverse in terms of climate ranging from desert to mountains to prairies.

Climate study regions (from paper) and Google maps (for geographic locations)

Climate study regions (from paper) and Google maps (for geographic locations)

The researchers wanted to look at 50 years worth of data so that they could take out the natural variations like El Niño and La Niña years as well as the Pacific Decadal Oscillation and just focus on the human-caused effects of warming (aka anthropogenic warming for those who like big words).

The researchers looked at several different climate indicators. They counted the number of frost days, the length of the growing season, number of warm days and warm nights, number of wet days (>5mm of rain), very wet days (wetter than >95% of all the other days), daily rain intensity, and annual rain totals.

They noted that while climate change will definitely increase the intensity of the hydrological cycle, the future trends of rain (where it will be, how much there will be) are much more difficult to predict. However, the overall trend found was for rain increasing in the Pacific Northwest (sorry Vancouverites!) more than other areas.

Another interesting thing they found was that natural variability in climate may be masking the effects of climate change in Canada more than in the USA, given the large number of extreme weather events recently observed in the US compared with relatively few extreme events in Canada. Which doesn’t mean we’re getting off scot-free Canada, it means climate change is coming for us later!

There were 490 weather stations that contributed data to the paper, which meant for some massive number crunching, added to the fact that they had to develop an additional computer program to convert all the US measurements into metric (Dear USA, please join the rest of the world and go metric!).

As you can see from the map above, the area was broken down into six different regions and analysed for climate trends. The results were:

Pacific Northwest

The Pacific Northwest saw a significant decrease in frost days at a rate of 2.4 days/decade and a significant increase in warm nights. There was a general increasing trend for all the other measurements – the growing season was extended, and all the rain indicators went up (yeah, winter really is getting wetter Vancouver). The researchers noted that the Pacific Northwest has experienced ‘significant warming’ over the 50 year period, and that the reduction in frost days has severe consequences for Pine Beetle infestations and increasing wildfires.

Frost days: significantly decreasing (from paper)

Frost days: significantly decreasing (from paper)

The one exception to the rule was Oregon, where a significant warm and dry patch in the southern part of the state is a sign of the Californian desert climate moving north as the temperature increases.

Rain totals: Dry patch over Oregon (from paper)

Rain totals: Dry patch over Oregon (from paper)

Northwest Plains (Wyoming, Montana, Alberta, Saskatchewan)

The Northwest plains saw a significant decrease in frost days at a rate of .16 days per year. There was a significant increase in the number of warm days and warm nights, with an increase in all other factors. While the increases in growing season and precipitation are beneficial so far, the researchers noted that continued warming will have detrimental effects on soil moisture and that the earlier spring runoff will pose challenges for water management.

Humid Continental Plains (North Dakota, South Dakota, Nebraska, Iowa, Minnesota, Manitoba)

Changes in this area were more extreme than the Pacific Northwest or the plains. There were significant increases in all indicators except for frost days, which saw a significant decrease. The researchers were concerned to note that warm nights are outnumbering cool nights in the continental plains by 5:1. The average rainfall is increasing by .11mm per year which will eventually have serious consequences as the paper notes that most farmland and urban areas in the continental plains are located on flood plains.

Gulf (Texas, Oklahoma, Kansas, Missouri, Arkansas, Louisiana)

The Gulf States saw the most significant increase in rain totals with annual averages going up by 2.8mm per year. There were also significant increases in the number of warm nights, wet days and rain intensity. While there was a significant decrease in the growing season length, it was most pronounced in the northern states and possibly linked to the significant decrease in frost days. Interestingly, there was a significant decrease in warm days, which the researchers think could be linked to the increase in rain (more clouds = less sunlight beating down on you).

American Southwest (Utah, Colorado, Arizona, New Mexico)

Climatically, this one is a real mixed bag going from amazing ski mountains all the way to New Mexican desert. However, there were still some overarching trends. There were significant increases in warm days and nights, rain totals, rain intensity and wet days. There was a significant decrease in frost days and an increase in very wet days and the growing season. The paper noted that while the increase in rain in the Southwest is currently positive, that growing extremes in temperature and the evaporation associated with it will likely negate this factor in the future.

One large concern was the decrease in frost days, given that much of the flow from the Colorado River comes from snowmelt, which was wonderfully understated as:

‘While best management practices may be able to mitigate the risk of widespread system failure, current levels of development in arid areas of the region may be unsustainable.’

This is scientist for ‘you either deal with this now, or something’s going to give in a really nasty way later’. Or, as one of my favourite climate bloggers Joe Romm says ‘Hell and High Water’ which will bring us the next Dust Bowl.

California-Nevada

The final segment in Western North America had significant decreases in frost days (as did all of Western North America), significant increases in warm nights and increases in all the other indicators. This may seem milder; however the researchers warn that California had substantial warming with only a slight increase in precipitation. This will be deadly as climate change continues. As the paper states:

‘A decline in the availability of water supplies may make the current intensive agriculture industry in California’s Central Valley unsustainable in the long term.’

Did you hear that? It’s the sound of your favourite Napa wine grapes shrivelling and dying in the heat.

The end of irrigated agriculture in California? (photo: flickr)

The end of irrigated agriculture in California? (photo: flickr)

So what does this all mean? Well, long story short it means that while we here in Canada aren’t experiencing the worst of climate extremes yet, and while each region of North America will change specifically based on their local climate, we haven’t seen anything yet.

The long term trends are pretty clear for most areas (or at least statistically significant) and the consequences for communities and industries aren’t good. And that’s even before you start to think about non-linear climate responses and ecosystem tipping points. So, for the sake of the wine in Napa, the skiing in the Rockies, the agriculture in the prairies and the people who call New Mexico home, let’s stop burning carbon.

Will the Well Run Dry? Non-renewable Water

Ancient groundwater sources are being depleted at fast rates and the impacts of climate change are still unknown

WHO: Richard G. Taylor, Department of Geography, University College London, London, UK
Bridget Scanlon, Bureau of Economic Geology, Jackson School of Geosciences, University of Texas at Austin, Texas, USA
Petra Döll, Institute of Physical Geography, University of Frankfurt, Frankfurt, Germany
Matt Rodell, Hydrological Science Branch, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
Rens van Beek, Yoshihide Wada, Marc F. P. Bierkens, Department of Physical Geography, University of Utrecht, Utrecht, The Netherlands
Laurent Longuevergne, Géosciences Rennes, Université de Rennes 1, Rennes, France
Marc Leblanc, School of Earth and Environmental Sciences, NCGRT, James Cook University, Cairns QLD, Australia
James S. Famiglietti, UC Center for Hydrologic Modelling, University of California, Irvine, USA
Mike Edmunds, School of Geography and the Environment, Oxford University, Oxford, UK
Leonard Konikow, U.S. Geological Survey, Reston, Virginia, USA
Timothy R. Green, Agricultural Systems Research Unit, USDA-ARS, Fort Collins, Colorado, USA
Jianyao Chen, School of Geography and Planning, Sun Yat-sen University, Guangzhou, China
Makoto Taniguchi, Research Institute for Humanity and Nature, Kyoto, Japan
Alan MacDonald, British Geological Survey, Edinburgh, UK
Ying Fan, Department of Earth and Planetary Sciences, Rutgers University, New Jersey, USA
Reed M. Maxwell, Department of Geology and Geological Engineering, Colorado School of Mines, Golden, Colorado, USA
Yossi Yechieli, Geological Survey of Israel, Jerusalem, Israel
Jason J. Gurdak, Department of Geosciences, San Francisco State University, San Francisco, California, USA
Diana M. Allen, Department of Earth Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
Mohammad Shamsudduha, Institute for Risk and Disaster Reduction, University College London, London, UK
Kevin Hiscock, School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, UK
Pat J.-F. Yeh, International Centre for Water Hazard and Risk Management (ICHARM), UNESCO, Tsukuba, Japan
Ian Holman, Environmental Science and Technology Department, Cranfield University, Milton Keynes, UK
Holger Treidel, Division of Water Sciences, UNESCO-IHP, Paris, France

WHAT: Looking at all the research on groundwater and working out what we know and what we don’t know

WHEN: 25 November, 2012

WHERE: Nature Climate Change, 2012 nclimate1744

TITLE: Ground water and climate change (subs req.)

Last month, 26 scientists all published a paper together on groundwater, which must have required either some massive Skype sessions, or people getting very sick of email chains where everyone hits ‘reply all’. As I’ve said before: science – it’s a collaborative thing.

What these researchers were trying to do was to work out exactly what we know about groundwater and how it will be affected by climate change and where the gaps are that we need to fill. Having worked in water policy, I can tell you that groundwater is normally the big unknown. Governments and organisations generally don’t have the information to know how much there is, who is taking it at what rates and how to monitor and regulate it. Generally, it gets put off until next time, while surface water rights are dealt with.

However, groundwater is estimated to be one third of all freshwater withdrawals worldwide and also the water source for 42% of the world’s agricultural water. So with climate change affecting rain patterns and shifting weather pole-ward, what will happen to groundwater? Will the well run dry in some places?

One of the biggest issues with measuring groundwater is the rate of recharge for the underground aquifers. These underwater storage vaults of water and mostly ancient water in that if you measure the isotopic composition of the water, they were likely filled thousands of years ago and have remained there without changing greatly.

Another interesting thing the isotopic analysis of the water tells us, is that if you look at the oxygen and hydrogen isotope ratios (so that’s the ratio of atoms that have different numbers of neutrons, making some heavier than others), many aquifers were filled in the late Pleistocene and early Holocene eras, around 12,000 years ago when the average temperature of the earth was around 5oC cooler than now.

Isotopic analysis: Hydrogen on the left and it’s isotope Deuterium (with the extra neutron) on the right

Isotopic analysis: Hydrogen on the left and it’s isotope Deuterium (with the extra neutron) on the right

What that means is that if those aquifers were recharging when the world was 5oC cooler than now, it’s unlikely that any recharge is taking place now or going to take place as we continue to heat our world through climate change. As the paper says ‘this non-renewable groundwater exploitation is unsustainable and is mined in a manner similar to oil’. Thousand year old water is just as renewable as million year old oil, and both are longer than a human life span.

So, what do we know about groundwater? There are two ways that groundwater can recharge: rain fed (the rain soaks into the ground) and surface water leakage (from rivers, irrigated agriculture or lakes). Both of these methods will be variable and vulnerable to climate change.

Changes in snow pack and snow distribution also impact recharge. The research currently published is still uncertain as to the extent of the impacts, but early findings are that the early start to spring is reducing the duration of recharge. Glacial retreat also impacts groundwater.

The other affects on groundwater are land use change and sea level rise inundating areas and making them salty. Managed ecosystems are not able to respond to change the way natural ecosystems can. Even if it’s a drought year, a farmer still needs to plant and crop their land. For each degree of climate change, you can roughly estimate that the equivalent climate will move 150km towards the pole. The desert of Salt Lake City will move north into the cropping areas of Idaho, and the slushy snow will move north into the ‘champagne powder’ ski regions.

More importantly, global estimates of groundwater depletion by 2050 range from 70% decreases in the Mediterranean and Brazil to increases in the Middle East and only 10% decreases in the Western US. There’s lots of uncertainty in the models as there’s a lack of data, so researchers need to extrapolate from incomplete data, resulting in large uncertainty margins.

One interesting thing I learned from this paper that I hadn’t considered before is that groundwater depletion increases sea level rise. How, you may ask? It’s the thing of living in a planetary system where everything is connected, so follow me through the water cycle here:

Thousand year old water that has been stored in the ground is pumped up a well and onto your farm. Some of the water will evaporate and the other water will grow plants, but the water has now gone into the atmospheric water cycle, so the evaporated water goes into the clouds, comes down as rain, and since 70% of our planet is ocean, there’s a really high chance the ancient groundwater will get added to the ocean. How much water? This is where it gets scary.

Groundwater water cycles (from paper)

Groundwater water cycles (from paper)

The paper talks about cubic kilometres of water. Yes, kilometres. I was unable to mentally picture that too, so I did a conversion for you. The groundwater depletion for the planet is between 145 – 204km3 of water per year, which is between 145,000 and 204,000 billion litres of water. To visualise this, you’d need to take the island of Manhattan and cover it twice with 1km deep water, which would be a depth of 4.5 Empire State Buildings end to end. This contributes between 0.4-0.5mm of sea level rise each year.

Climate change will have an effect on groundwater resources. Exactly what that is won’t be known until all the data is collected to create detailed models. However, sustainable aquifer management is going to be difficult and grow increasingly difficult as the climate continues to change.