The University of Southampton

Tag: Crop Failure

Crops and Climate Change: the good, the bad and the ugly truth

Posted on by Anonymous

New Year, New Hope? But 2017 began with Britain being hit with a vegetable shortage!

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(Independent, 2017)                                                    (The Guardian, 2017)

But apart from halting our “clean eating” resolutions…..

Is a courgette shortage really the end of the world?

Well, probably not! But globally, food security is no laughing matter.

 And what is the cause you may ask? Climate change, of course!

The evidence for climate change is overwhelming.

The Earth’s average temperature has increased by 0.85°C between 1980-2012 (IPCC, 2014). This may seem insignificant, yet, it has severe consequences, such as the ice caps melting, sea levels rising and increased occurrence of extreme weather events (Overpeck and Cole, 2006).

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Globally averaged combined land and ocean surface temperature (IPCC, 2014)

Humans are to blame.

Since the industrial revolution, burning of fossil fuels has increased emissions of carbon dioxide (CO2) and other greenhouse gases (GHGs) These GHGs act as a blanket, trapping energy in the atmosphere, causing Earth’s temperature to rise (IPCC, 2014).

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Global Human CO2 Emissions, IPCC, 2014

The good?

Higher CO2 levels increase plant photosynthesis (Pospisilova and Catsky, 1999). Photosynthesis depends on an enzyme called Rubisco, which evolved at higher prehistoric CO2 levels, therefore has higher activity when CO2 increases (Bowes, 1996). This increases plant growth, thereby increasing crop yield, in a phenomenon termed “CO2-fertlisation” (Allen, 1990).

This is particularly pronounced plants categorised at C3 , which includes major crops such as rice, wheat and soybean. Increasing CO2 to 550pm causes 10-20% increase in C3 crop yield, but only 0-10% increase plants categorised as C4, which includes the crops maize and sorghum (Schmidhuber and Tubiello, 2007).

CO2 enters plants through stomata (plant pores), therefore, at higher CO2 levels the stomata need not open as often, termed reduced stomatal conductance. This decreases the amount of water lost through the pores in the process of transpiration, thereby increasing the water efficiency of the plants (Drake et al., 2007).

The bad?

So, is climate change good for plants if it causes increased growth and higher water efficiency? Well no, it was never going to be that simple…

Extreme weather events negatively impact food security, both directly by reduced yields from damaged crops but also indirectly by increasing the chance of landslides and soil erosion, thereby reducing the land available for agriculture (Cerri et al., 2007).

This issue is becoming more urgent as global population increases at an unprecedented rate, increasing the demand for food (MA, 2005).

Food security issues are not only concerned with the quantity of food but also the quality, as globally many people suffer from malnutrition (MA, 2005). Elevated CO2 decreases the zinc, iron, and protein content in wheat, barley, and rice (Myers et al., 2014).

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The two-fold effect of increased CO2 form increased carbon emissions; most likely the negative effect will outweigh the positive effect. 

The ugly truth

Unfortunately, it is predicted the losses will outweigh any gains from CO2 fertilisation.

Ultimately, lack of food could see increased prices for consumers in the developed world whilst the developing world will suffer with food shortage and malnutrition.

Lack of courgettes may seem a trivial matter but is it just one more sign that we getting closer to the tipping point of our planet’s ability to cope with climate change.

Word count: 499

References

Allen, L.H. Jr. (1990). Plant responses to rising carbon dioxide and potential interactions with air pollutants. J. Environ. Qual, 19: 15-34.

Bowes G. (1996) Photosynthetic responses to changing atmospheric carbon dioxide. pp. 387-407. In: N.R. Baker (ed.). Photosynthesis and the Environment. Advances in Photosynthesis, Vol. 5, Kluwer, Dordrecht

Cerri, C. E.P., Sparovek, G., Bernoux, M., Easterling, W.E., Melillo, J. M., and Cerri C. C. (2007). Tropical Agriculture and Global Warming: Impacts and Mitigation Options. Sci. Agric., 64(1): 83-89.

Drake, B.G., Gonzàlez-Meler, M.A. and Long, S.P., 1997. More efficient plants: a consequence of rising atmospheric CO2? Annual review of plant biology, 48(1): 609-639.

IPCC. (2014) Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. R.K. Pachauri and L.A. Meyer (eds.). IPCC, Geneva, Switzerland, pp. 151.

Millennium Ecosystem Assessment (2005). Ecosystems and Human Well-being: Synthesis. Island Press, Washington, DC.

Myers SS, Zanobetti A, Kloog I, et al. (2014). Rising CO2 threatens human nutrition. Nature. 510(7503): 139-142.

Overpeck, J.T. and Cole, J.E. (2006). Abrupt change in Earth’s climate system. Annual Review of Environment and Resources, 31: 1-31.

Pospisilova, J. and Catsky, J. (1999). Development of water stress under increased atmospheric CO2 concentration. Biologia Plantarum, 42: 1-24.

Schmidhuber, J. and Tubiello, F.N. (2007). Global food security under climate change. Proc. Natl. Acad. Sci. USA, 104(50): 19703-8.



Popeye didn’t cause the spinach shortage: why the effects of global environmental change on plant function is a double-edge sword

Posted on by Anonymous

Climate change – a myth? We have all heard of it and its impending threat to our global environment. However, what we should ask ourselves is how are plants affected by our planet’s increasing temperatures, carbon dioxide (CO2) levels and the increasing frequency and intensity of severe weather changes?

Diagram illustrating some factors mentioned that are linked to climate change and their impact on several biological processes carried out in plants
Diagram illustrating some factors mentioned that are linked to climate change and their impact on several biological processes carried out in plants (Source: (Kallarackal and Roby, 2012))

Plants play a critical role in pulling CO2 out of the atmosphere. This uptake of CO2 during photosynthesis is a major pathway by which carbon can be stored (Tkemaladze and Makhashvili, 2016). Carbon dioxide is predicted to increase to approximately 1000 ppm by 2100. Since the beginning of the Industrial Revolution approximately 200 years ago average global temperatures have increased by 0.85°C and by the end of the century temperature is projected to rise by approximately another 4°C (IPCC, 2013).  Some would assume this to be beneficial to plants due to these warmer temperatures and increased levels of gas as it should, in theory, encourage growth. However, it is not as straight forward as this.

The enzyme rubisco is the key to this photosynthetic process by fixing CO2. Drake et al. (1997) states that the increased levels of CO2 will allow greater fixation by plants and, therefore, result in increased growth. However, Bisgrove and Hadley (2002) found that long-term exposure to elevated levels of CO2 caused an accumulation of carbohydrates in plant tissues, which in turn reduced the rate of photosynthesis. Furthermore, although plants initially respond positively to increasing temperature, this will eventually plateau or even decline after reaching the optimum range for some species. Plants may experience an increased rate of respiration leading to death; illustrating the world’s plants can easily lose their ability to act as a global carbon sink, becoming instead yet another carbon source (Mellilo et al., 1990; Hawkins et al., 2008).

Moreover, another consequence of global environmental change is a change to global weather patterns. Many do not connect climate change with uncharacteristic weather events, however, there is no doubt that climate change affects their intensity and frequency. Thus, in the future, we can expect to experience more frequent periods of drought, floods and storms (Frich et al., 2002). For example, during the past winter, there was snow escape in Spain as we witnessed a window to our future in the form of the courgette and spinach crisis, which caused havoc and rationing in British supermarkets. Yet these changing weather patterns will have a much larger impact than just a blow to spiralizer sales.

 

The heavy snowfall the province of Murcia in Spain experienced this winter ruining many crops.
The province of Murcia in Spain experienced heavy snowfall this winter ruining many crops (Source:http://edition.cnn.com/2017/02/03/europe/lettuce-shortage-europe/)

Stated above are only a few effects global climate change has on our planet’s plants. Plants have an essential regulatory role in the control of our planet’s climate: they did yesterday, they do today and they most certainly will in the future. If we continue to allow the CO2 level to increase at the rate it is currently we will suffer dramatic consequences. It not only will affect the Earth’s vegetation such as forests and plants, but will also have a knock-on effect on global food production, therefore, affecting our wellbeing.

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References

Bisgrove, R. and Hadley, P. (2002). Gardening in the global greenhouse: The impacts of future landuse and climate on the red list status of the Proteaceae in the cape floristic region, South Africa. Global Change Biology, 69, pp.79-91.

Drake, B., Gonzàlez-Meler, M. and Long, S. (1997). More efficient plants: A Consequence of Rising Atmospheric CO2?. Annual Review of Plant Physiology and Plant Molecular Biology, 48(1), pp.609-639.

Frich, P., Alexander, L., Della-Marta, P., Gleason, B., Haylock, M., Klein Tank, A. and Peterson, T. (2002). Observed coherent changes in climatic extremes during the second half of the twentieth century. Climate Research, 19, pp.193-212.

Hawkins, B., Sharrock, S. and Havens, K. (2008). Plants and climate change; which future? Richmond, UK: Botanic Gardens Conservation International, pp.98.

IPCC (2013) Climate Change 2013: The Physical Science Basis.Intergovernmental Panel on Climate Change, Cambridge, UK.

Kallarackal, J. and Roby, T. (2012). Responses of trees to elevated carbon dioxide and climate change. Biodiversity and Conservation, 21, pp.1327-1342.

Melillo, J., Callaghan, T., Woodward, F., Salati, E. and Sinha, S. (1990). Effects on Ecosystems, in Climate Change: The IPCC Scientific Assessment, edited by J. Houghton, G. Jenkins, J. Ephraums, Cambridge University Press, Cambridge, pp.283−310.

Tkemaladze, G. and Makhashvili, K. (2016). Climate changes and photosynthesis. Annals of Agrarian Science, 14, pp.119-126.



Believe it or not… CLIMATE CHANGE WILL TRUMP U.S.!

Posted on by Hannah Lesbirel

By Hannah Lesbirel student at University of Southampton

You’ve all seen images of famine and the effect of crop failure on families across the globe. Have you ever pictured that being you? No, me neither.

Surely that can’t happen in the USA- “The greatest country in the World”- people say?

Queues for food rations. This is happening somewhere in the world right now! Imagine, this could be you if nothing is done to reduce the impacts of climate change. Source: http://answersafrica.com/starvation-and-famine-in-africa.htm
Queues for food rations. This is happening somewhere in the world right now! Imagine, this could be you if nothing is done to reduce the impacts of climate change. Source: AnswerAfrica

Some experts argue the increase in CO2 levels, associated with climate change, may in fact contribute to gains in some crops, in some regions of the world. Surely more CO2 means more photosynthesis, right?

However, the negative impacts associated with climate change are expected to reverse the potential benefits (Nelson et al., 2009). Climate change indisputably impacts: global temperatures, frequency and intensity of extreme weather events, CO2 levels and water availability, and without availability of sufficient water and nutrients photosynthesis can’t thrive (Nelson et al., 2009; Hatfield et al., 2011).

The video below summarises the limiting factors of photosynthesis and how they could be influenced by the changing environment.

Temperature Variability

The rate of plant development is primarily influenced by temperature, impacting (Hatfield and Prueger, 2015);

  • Pollen viability
  • Fertilisation
  • Water requirements
  • Grain and fruit formation
  • Length of life cycle

All plants have an optimum temperature in which photosynthesis takes place, too high and enzymes are denatured and too low the catalytic efficiency of these enzymes are reduced. Additionally, higher temperatures are known to encourage weeds, pests and disease.  The figure below shows the predicted temperature due to climate change globally by 2050 (Nelson et al., 2009). If this rise in temperature is to continue, this will reduce crop yields across the globe.

Source: Nelson et al., 2009
Predicted increase in global temperatures by 2050. Source: Nelson et al., 2009
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Once luscious fields becoming barren due to decreased yields as a results of climate change. Source: Crated and Nature 

With warmer temperatures predicted along with the increased probability of extreme temperature events, plant productivity is at serious RISK! Estimations show a significant decline in yields, of between 80-90%, compared to ‘normal’ conditions (Hatfield and Prueger, 2015).

Changes in Precipitation

The concern of rising global temperatures, will be proliferated by changes in precipitation. Increasing the likelihood of crop failure and long term production decline (Nelson et al., 2009).

Despite uncertainty in precipitation change, under future climate change scenarios, the impact of excess and deficit amounts of soil water will be negative for crop production, either drowning or starving the crops of water (Hatfield et al., 2011).

It’s been said that “stronger interannual variability with more extreme year-to-year climate variations…[means] farmers are unable to tune their cropping systems to optimize resources (Bannayan et al., 2010).”

Not only will this have a major impact on human health and well-being. Agriculture contributes over $300 billion to the U.S. economy each year; think of the impact this may have on your health and livelihood.

Decline of Global Markets

On a more global scale, the potential decline in production will reach international levels, as U.S. farms supply 25% of all grain (soybean, wheat and maize) on the global markets (Nelson et al., 2009; USEPA, 2016).

screen-shot-2017-03-06-at-13-24-35
The cycle that could follow the decline in grain production (Nelson et al., 2009).

The ‘domino’ effect of a decline in grain productivity is incomprehensible. The cycle that could follow is shows to the right.

Could we be building a wall between us and future generations? Progress is needed to prevent this shocking reality.

Read more information about the impact of Climate Change on global agriculture from the FAO report on Climate change: Impact on Agriculture and Costs of Adaptation.

 

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Read More:

http://ecoethics.net/cyprus-institute.us/PDF/Rosensweig-Food-Supply.pdf

http://bioenv.gu.se/digitalAssets/1432/1432197_fantahun.pdf

http://www.pnas.org/content/106/37/15594.full