Is It Hot in Here?
'unless humans change the way we behave, it is not going to slow down'
Charlotte Harrison | 3 March 2016

We all know what Global Warming is – the world is gradually warming up. We know that, unless humans change the way we behave, it is not going to slow down. The earth’s temperature fluctuates naturally, however, since 1900, the average global temperature has increased by 0.6 degrees Celsius, which is a very significant increase. The most widely-accepted theory to explain this is that an increase of greenhouse gases in the atmosphere has lead to an increase in the average temperature on earth. Research by CO2.Earth has shown that, from 2005 to 2014, the average rate of increase of CO2 annually was 2.11 ppm (parts per million). This is more than double the rate of increase in the 1960s!

Due to changes in temperature, CO2 concentration and the frequency of extreme weather across the globe, there have been significant changes to global food production. There has a been an increase of the world's average temperature which, despite increasing the rate of growth of crops, may well decrease the crop yield of plants, especially grains. This is because the faster the rate of growth, the less time given to seeds to mature, and therefore the higher frequency of failed crops. Enzymes within a type of crop will work more slowly, even though the plant is growing faster, and eventually plants will die. This happens much more frequently after even a small increase in temperature.

A recent Stanford University study found that the global production of wheat and maize since 1980 would have increased by 5% if it were not for Global Warming. However, an increase in temperature will have different effects on the growth of crops. In some areas it may increase the yield (if the temperature is not exceeding its optimum level) whereas it may decrease the yield in others, where the temperature is too high for the crop to grow successfully.

Furthermore, an increase of CO2 may actually have a positive impact on the crop yield. This is because carbon dioxide is a gas essential for the photosynthesis of plants and therefore respiration. The more carbon dioxide there is, the more photosynthesis a plant can do and therefore the more successful its growth. Plants find it easier to extract carbon dioxide from the air to make carbohydrates. However, the other factors are more limiting of the global crop yield, and therefore there has been a general decrease in crop yield globally despite the increase in carbon dioxide levels.

Additionally, the increase in extreme weather due to Global Warming has also had an effect on crop yields globally. Most importantly may be the greater frequency of droughts. For example, there have been multiple, extensive droughts in America, including the 2006–2011 drought in the state of California. As a result of these droughts there is a great reduction in the availability of water for crops, and therefore a greatly reduced yield and quality of the crops. This has been the case in many countries in Africa, and has been a real problem globally.

Lastly, the rise in sea levels due to the melting of the ice caps from Global Warming could have an impact on crop growth. This is because the oceans could flood into low-lying land, for example much of Bangladesh. This means that it could also flood much of the fertile land, and cultivation of crop plants would be difficult. This could happen, especially if the water travels down rivers further into these countries.

Furthermore, there have been considerable effects on the distribution and numbers of animals and pests from Global Warming. The geographic distributions of most animal and plant species are limited heavily by climatic factors, including rainfall, humidity, temperature, soil moisture and wind. As previously highlighted, there have been changes to these factors recently. Animals affected by heat may move to cooler locations, such as mountainous regions. This may not seem so bad in itself, however the movement of a species from an area will disrupt the ecosystem, and could well disorder the food chain. Winter adapted birds have begun to move further north. This is most likely due to the increase in temperature, so that the area is too warm and they then move to find a cooler environment. An example of this can be seen in the movement of bird species such as the Carolina Wren which have begun to move northwards, which many attribute to the effects of Global Warming. Of course, animals can react much faster, in terms of distribution, than plants can. It is predicted that there will also be changes in the ranges of vegetation, and models have been used to evaluate these changes. They have predicted the poleward shift of vegetation such as the boreal conifer.

So the real question is not if we can cope with some different weather here and there, but if we will actually be able to survive with the ever-changing ecosystem worldwide. Can you feel the heat? 

Original photo by Harriet Fisk

James Routledge 2016