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.

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Let Them Eat Cake? Feeding 9 Billion People

What changes will need to be made to agricultural practices in order to double food production for predicted population growth this century?

WHO: Jonathan A. Foley, Kate A. Brauman, Emily S. Cassidy, James S. Gerber, Matt Johnston, Nathaniel D. Mueller, Christine O’Connell, Deepak K. Ray, Paul C. West, John Sheehan, Institute on the Environment (IonE), University of Minnesota, Saint Paul, Minnesota, USA
Navin Ramankutty, Department of Geography and Global Environmental and Climate Change Centre, McGill University, Montreal, Quebec, Canada
Christian Balzer, Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, California, USA
Elena M. Bennett, School of Environment and Department of Natural Resource Sciences, McGill University, Montreal, Quebec, Canada
Stephen R. Carpenter, Center for Limnology, University of Wisconsin, Madison, Wisconsin, USA
Jason Hill, Institute on the Environment (IonE), University of Minnesota, Department of Bioproducts and Biosystems Engineering, University of Minnesota, Saint Paul, Minnesota, USA
Chad Monfreda, Consortium for Science, Policy and Outcomes (CSPO), Arizona State University, Tempe, Arizona, USA
Stephen Polasky, Institute on the Environment (IonE), University of Minnesota, Department of Applied Economics, University of Minnesota, Saint Paul, Minnesota, USA
Johan Rockström, Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden
Stefan Siebert, Institute of Crop Science and Resource Conservation, University of Bonn, Bonn, Germany
David Tilman, Institute on the Environment (IonE), University of Minnesota, Department of Ecology, Evolution& Behavior, University of Minnesota, Saint Paul, Minnesota, USA
David P. M. Zaks, Centre for Sustainability and the Global Environment (SAGE), University of Wisconsin, Madison, Wisconsin, USA

WHAT: Looking at all of the recent research on agricultural processes and working out how we can feed 9 billion people without also cooking the climate

WHEN: 20 October 2011

WHERE: Nature, Vol. 478, October 2011

TITLE: Solutions for a cultivated planet (subs req.)

Currently, 1 in 8 people globally lack access to food or are chronically malnourished. This alone is a large problem for world food systems, however with the population expected to increase to 9 billion by 2050 the problem just got even bigger. Our agricultural food systems are estimated to require doubling in order to feed all those extra people.

How will agricultural food systems have to change this century to provide global food security while also reducing the environmental impacts that agricultural practices have caused leading to increasing climate change?

This is the question these researchers set out to answer in another wonderful example of science being a collaborative sport.

Image: NASA

Image: NASA

Agriculture currently uses 50% of the earth’s ice-free surfaces. 12% is used for crops we eat directly, while 38% is used for pasture to grow livestock as well as other things like biofuels (2%). We as a species have used pretty much all the land that is available on the planet for agriculture – the land we haven’t farmed is tundra, desert, mountains or cities. Agriculture is the single biggest land use on the planet.

Innovation is going to be the major key to increasing global food production in this century, given that there’s not much more land we can farm on effectively. Global crop yields increased by 56% between 1965-1985 with the advent of mechanised and industrialised agricultural practices. However, between 1985-2005 yields only increased by a further 20%, and yields are increasing by smaller margins each year.

The four major solutions this group of researchers came up with to feed the world sustainably were:

1. Ending Agricultural Geographical Expansion

Most of the land currently being cleared for new agriculture is in the tropics and contributing to tropical deforestation. This is an issue for two reasons: firstly because deforestation worldwide is a huge contributor to greenhouse gas emissions and climate change, but also secondly because most tropical land is less productive than land that is already being farmed. This means that the productivity gained is less than the greenhouse gasses emitted through the deforestation.

Luckily for the authors of the paper, one of the major drivers of tropical deforestation is local economic drivers, which means the solution to this issue is socio-economic and this group of scientists will leave that for the economists.

2. Closing Yield Gaps

Recent research has looked at ‘yield gaps’ which is where different farms in the same area with the same soil and climate conditions end up with different crop yields. Closing those yield gaps and making sure each farm is as productive as possible is one gap that could contribute greatly to feeding the world. The research shows the greatest room for improvement is in areas of Africa, Latin America and Eastern Europe.

Closing the yield gap by 95% (so that your farm is 95% as productive as your neighbour’s farm) could increase world food production by 58%. If we only managed to close the yield gap by 75%, there would still be a 28% increase in food production.

However, doing this while simultaneously reducing the environmental impacts from intensive agriculture requires farmers to look more at Precision Agriculture methods.

3. Increased Efficiency

The current agricultural usage of water, nutrients and chemicals is unsustainable. Excess nutrient use has affected Nitrogen and Phosphorus cycles which has led to farmland without enough soil nutrients because of losses in the agricultural processes and deadzones in oceans from too much nutrient runoff.

The research found that nutrient excesses were worst in areas of China, Northern India, the USA and Western Europe, and recommends that these countries implement nutrient recycling and recovery programs to minimise use.

4. Food Delivery Systems

Food delivery systems need to be reformed in order to feed 9 billion people. The paper points out that a dietary shift away from meat would make land much more productive as it would be growing crops for direct human consumption, but they’re also realistic about how unlikely it is that we’ll all become vegetarian.

However there are much more immediate efficiencies to be found reducing waste in supply chains. The UN Food and Agriculture Organisation estimates that 1/3 of all food is never consumed. It either gets damaged in transit, or is not sold and gets thrown out. Making our supply chains from farm to table shorter and more efficient will be key to feeding the world.

Feeding the world: Don’t forget the wine! (Chris Gin, flickr)

Feeding the world: Don’t forget the wine! (Chris Gin, flickr)

The researchers point out that feeding 9 billion people successfully will only be possible if all of the above strategies are implemented at once. Better yields and food delivery systems won’t be very useful if deforestation continues and climate change starts wiping out all the yield gains. Similarly, ending deforestation alone won’t be very useful if water and nutrient use don’t become more efficient and yields are affected by shortages.

The paper suggests scaling up some solutions that are already being implemented by some farmers like precision agriculture, drip irrigation, organic soil remedies (like no-till farming), buffer strips and wetland restoration in low lying areas, drought resistant crops and low fertilizer crops, perennial grains and paying farmers for environmental services.

As with combating climate change, feeding the world is going to take new and innovative practices which not only improve the farming business, but also improve the resilience of agricultural food systems, and all of these solutions need to be tried simultaneously. But I guess no-one ever said solving the world’s problems was going to be easy!

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.