The University of Southampton

Tag: drought

Climate Change IS happening, and it’s set to starve the planet… (The opposite of FAKE NEWS!)

Posted on by Anonymous

With the large scale funding cuts of the Environmental Protection Agency in the USA, the current rapid rates of climate change and CO2 release show no hope of stopping.

But seeing as though plants breathe using CO2 (through the process of photosynthesis), and use carbon in their growth, surely the increased amounts of CO2 being pumped into our atmosphere is a good thing for plants?  As studies have shown; perhaps not…

Plants require very specific environmental conditions to function efficiently, and any changes in these conditions can be detrimental.  Although it has been shown that increased CO2 initially causes an increase in the rate of photosynthesis and growth of leaves and roots (Taylor et al 1994), generally, in the long-term, the stimulation of photosynthesis is actually suppressed!

This is mainly due to negative effects on the plants function, such as the build-up of excess starch (sugars) in leaves via increased photosynthesis, hindering breathing of CO2 via pores; called the stomata (Makino & Mae 1999), and increased CO2 also causes the stomata to partially close (Singh 2009), resulting in an inability to respire efficiently (Ryan 1991).

The mechanism for respiration in a plant leaf, through the stomata.
The mechanism for gas exchange in a plant leaf, through the stomata.  Source: Understanding Evolution

The failure to respire efficiently can cause the death of many food crops globally that are vital to feeding our populations!

Increased environmental CO2 also results in global warming due to increased reflection of the Sun’s radiation back to the Earth’s surface; and a temperature increase of 2-3⁰C over the next 30-50 years (IPCC 2007) is predicted to cause problems for our crops.  For example, warmer temperatures affect plants mainly when they are developing, and this has been shown to reduce the numbers of our food crop plants by 80%-90% (Hatfield & Prueger 2015), having dire consequences for our food supplies!

The global change in surface temperature from 1901-2012. A worrying trend that is set to worsen... Source: National Snow & Ice Data Center
The global change in surface temperature from 1901-2012. A worrying trend that is set to worsen… Source: National Snow & Ice Data Center

Climate change is also set to increase the frequency of extreme weather events (Rosenzweig et al 2001). With increased storms and flooding drowning plants in some areas, and in other areas increased drought, resulting in a lack of water for plants to function with, which they rely heavily on for processes such as photosynthesis, vital for growth and survival.  The equation for photosynthesis is shown below, in case you have forgotten…

 

The equation for photosynthesis, showing how carbon dioxide and water are transformed into oxygen and sugars through the light energy from the sun hitting the chlorophyll pigments in the plants cells.
The equation for photosynthesis, showing how carbon dioxide and water are transformed into oxygen and sugars through the light energy from the sun interacting with the chlorophyll pigments in the plants cells.

 

With increasing global temperatures, drought affected areas will increase from 15.4% to 44.0% by 2100 (Li et al 2009) – resulting in less land to grow crops, which will be disastrous for our food security, along with the fact that the number of suitable growing days per year for our crops will decrease by 11% by the year 2100 (Mora et al 2015)!

A sunny day on a Californian beach? Not exactly… This is Californian farmland suffering from a severe drought – completely unusable!
A sunny day on a Californian beach? Not exactly… This is Californian farmland suffering from a severe drought – completely unusable! Source:  New York Times

 

With the saying “Feed the World” becoming more and more poignant, our future looks bleak, as we are set to have less food security per person than ever before due to the detrimental effects that climate change will have on plant function. Also, plants not only provide food, but are also at the heart of our medicines and resources! So maybe Donald Trump ought to reconsider his views on climate change before threatening his new healthcare system before it has begun.

Word Count: 500

 

References:

Hatfield, J. and Prueger, J. (2015). Temperature extremes: Effect on plant growth and development. Weather and Climate Extremes, 10, pp.4-10.

IPCC, (2007). Climate Change 2007: Impacts, Adaptation and Vulnerability. New York: Cambridge University Press, p.17.

Li, Y., Ye, W., Wang, M. and Yan, X. (2009). Climate change and drought: a risk assessment of crop-yield impacts. Climate Research, 39, pp.31-46.

Makino, A. and Mae, T. (1999). Photosynthesis and Plant Growth at Elevated Levels of CO2. Plant and Cell Physiology, 40(10), pp.999-1006.

Mora, C., Caldwell, I., Caldwell, J., Fisher, M., Genco, B. and Running, S. (2015). Suitable Days for Plant Growth Disappear under Projected Climate Change: Potential Human and Biotic Vulnerability. PLOS Biology, 13(6), p.e1002167.

Rosenzweig, C., Iglesius, A., Yang, X., Epstein, P. and Chivian, E. (2001). Climate change and extreme weather events – Implications for food production, plant diseases, and pests. Global Change & Human Health, 2(2), pp.90-104.

Ryan, M. (1991). Effects of Climate Change on Plant Respiration. Ecological Applications, 1(2), pp.157-167.

Singh, S. (2009). Climate change and crops. 1st ed. Berlin: Springer, pp.5-6.

Taylor, G., Ranasinghe, S., Bosac, C., Gardner, S.D.L. and Ferris, R. (1994). Elevated CO2 and plant growth: cellular mechanisms and responses of whole plants. Journal of Experimental Botany, 45, pp.1761-1774.



DROUGHT: Destroying the Central Valley Wetlands, but what about all the Wild Life?

Posted on by Sophie Cox

Welcome to California, the place of sunny dreams, but this dream in the case of waterfowl has become a terrifying nightmare.  The state of wetlands in the Central Valley was described as “discouraging” back in 1949 by Day, but it’s safe to say it’s got a lot worse, with over 95% now gone or threatened,  something tells me we should have been paying more attention 65 years ago!

2014toon29
The ironic tourist welcome is not so welcoming to migatory birds. (http://www.startribune.com/summer-time-out-from-heat-humidity/268977201)

The ‘Pacific Flyaway’ is the migratory pathway millions of birds undertake every year from their northern breeding grounds in Canada and Alaska.  It’s believed up to 60% of migratory birds stop off in the Central Valley for the summer time (Dasman, 1966).

But surely people aren’t the problem ?

Drought is a massive problem throughout the world but just to add to the pressure of an already warm climate let’s add the stress of agriculture and urban growth. California is the leading agricultural state in the USA (Mills, 1997) and with this, demand for water is high and legislation has made this a priority over wildlife.

Smart or Stupid, well that’s a personal opinion… but with only 25% of central valley having an “adequate water supply” we then go and take 87% of this and use it for irrigation (Kahrl, 1979). Oh and don’t forget the pesticides sprayed all over the crops polluting the water.

No wetlands, what’s the problem ?

So, wetlands are disappearing, but they aren’t that critical to a community? Wrong!

The Central Valley is ‘Feeding Ground Central’ for over 5 million bird, but with the loss of wetlands. The question is where do all these birds find food?

The options

They can overcrowd in the remaining wetlands, however, food limitations occur as early as mid winter/ early spring (Petrie et al., 2016). Flies and insects struggle to have successful hatching due to lack of stagnant water, and those within the sediment and plants desiccate. Meaning food sources of the waterfowl are greatly effected by this fragmentation.  Oh and to top it off the rate of disease sky rockets with overcrowding. Cases have documented die offs of over quater of a million ducks as a result of avian diseases (Hunter et al., 1970).

111122_texas-drought-grid-8x2
Drought stricken wetland, no birds or food in sight! (Photo by Patrick Dove/ San Angelo Standard-Times via AP)

Or

They can settle on agricultural land, shifting their habitat and dietary requirements. So it’s all fine, right? 50% of these migratory birds now rely on waste rice/grain crops for their energy source instead of plants and insects previously found in wetlands, they have learnt to exploit a new niche. Great!

banner_trumpeterswan
Swans feeding on Agricultural Land (Photo by Markus Merkens)

 So the community has changed, they found food so it’s all fine?

This really would be the ideal situation, Sadly, despite over coming dispersal barriers by flight, drought has greatly restricted the habitat and has drastically changed the community composition by desiccation and lack of hatching success of insects and flowering plants. The adaptation of diet change to exploiting crops still posses great risk as everything is still water dependant.

The effects on the community are already drastic but how far could drought really push the wildlife all over the world?

References

Day, A.M. (1949) North American Waterfowl. The stack-pole Co., Harrisburg, Pennsylvania, pp.363

Dasmann R.F. (1966) The Destruction of California, Collier Books, New York City, 10tth pp.203-223

Hunter, B.F., Clark, W.E., Perkins, P.J., Coleman, P.R. (1970) Applied Botulism Research Including Management Recommendations- a progress reports. California Department of Fish and Game, Rancho Cordova, California, USA. pp.37

Kahrl, W.L. (1979) The California Water Atlas, Governor’s Office of Planning and Research in cooperation with the California Department of Water Resources, Sacramento, California

Mills, P.K. (1997) Correlation Analysis of Pesticide Use Data and Cancer Incidence Rates in California Counties. Archives of Environmental Health : an international Journal. 53(6), pp.410-413

Petrie, M., Fleskes, J., Wolder, M., Isola, C., Yarris, G. and Skalos, D. (2016). Potential Effects of Drought on Carrying Capacity for Wintering Waterfowl in the Central Valley of California. Journal of Fish and Wildlife Management, 7(2), pp.408-422.

Word count :495