Predicting the Effects of Global Warming

James Orr 

Using geothermal heat and natural laboratories to predict what will happen to ecosystems as the Earth warms. 


The earth is warming at an alarming rate. 2014 and 2015 were both the hottest years ‘on record’ and 2016 looks like it is going to continue the trend [1]. The vast majority of climate scientists predict at least a 2°C increase in mean global temperature by the end of this century [2].


May have been stolen from one of caroline’s blogs. Image source

Dr. Eoin O’Gorman, an independent research fellow from Imperial College London, focuses much of his work on predicting the ecological impacts of global warming. His work is important because a rise in temperature is inevitable and understanding how ecosystems will react to this anthropogenic crisis will be critical in conserving the planet’s biodiversity.

Not Dr. O’Gorman, and not how he predicts the effects of global warming. Image source

Controlled experiments have been carried out in labs to determine what will happen to ecosystems as the earth warms. These experiments have demonstrated some interesting effects at the species level and below but are too short in duration and too small in scale to predict how entire ecosystems will react to this ominous temperature rise [3].

O’Gorman uses unique study sites with differential degrees of geothermal energy to predicts the impacts of global warming on an ecological level. The Polar Regions are expected to experience the greatest levels of warming in the coming decades and will be the first the show the biological effects. O’Gorman claims that these these ‘sentinel systems’ are the most important ones to understand so that we can predict what will happen elsewhere. So his natural warming experiments need to be Polar Regions with high levels of geothermal activity. Iceland was a perfect candidate.

Landmannalaug hot spring in Iceland. Image source

O’Gorman calculated ecological values such as species richness, trophic transfer efficiency and mass-abundance relationships in a number of different streams. What was interesting about these streams was that, although they were within the same valley system, there was a range in temperatures across the streams from 5°C to 25°C. The streams were similar in chemistry, size and structure. This natural laboratory had isolated temperature as the only explanatory variable.

The streams that O’Gorman uses in his research. Image source

O’Gorman hypothesized that the groups of organisms in the warmer streams would be small on average and that there would be a shift in the mass-abundance scale towards fewer large things and more smaller things. However, his results showed the opposite. There was a surprising pattern in the mass-abundance relationship in the assemblages of organisms as temperature increased in the streams.

The mass-abundance results from O’Gorman’s experiments – not what was expected. Image Source

These unexpected results indicate that the theoretical effects of global warming may not be universal. For example in this ecosystem the a rapid turnover of nutrients and of diatoms at higher temperature mean that smaller abundances of primary producers are required to support larger abundances of larger animals. For example the apex predator in this system, trout, was only found in the warmer streams. This goes against the hypothesized predictions of global warming that apex predators will be the first to go extinct.

O’Gorman’s experiment is a very specific example but it still shows that the predicted effects of global warming may not be ubiquitous and that some ecosystems may react unexpectedly. He and his colleagues hope to expand their research to other areas with suitable conditions, such as Alaska, Kamchatka and Svalbard. Hopefully this work provides even more insights into the effects of global warming to biological systems because we need to be prepared if we stand any chance in stopping the Anthropocene mass extinction that is going on around us.






3) O’Gorman EJ, Benstead JP, Cross WF, Friberg N, Hood JM, Johnson PW, Sigurdsson BD, and Woodward G (2014). Climate change and geothermal ecosystems: natural laboratories, sentinel systems, and future refugia. Global Change Biology, 20, 3291-3299.

Feature image source:




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