Our planet is at risk and the past could hold the key to the future
by Dr. Dominique Dodge-Wan
Geologists often refer to the concept of uniformitarianism devised by geologists James Hutton and Charles Lyell in the 18th Century. Its principle is that “the present is the key to the past” since physical processes operating today would have also operated in the past. Those processes shaped the earth’s landforms in the past in the same way they do today.
It allows geologists to infer past environments (palaeoenvironments) from knowledge gained studying present environments and their geological products. For example, we observe that coral reef organisms thrive where there is sufficient light underwater for photosynthesis. Hence, we can expect that in the geological past, similar organisms lived at similar water depths.
I would like to turn the principle around and suggest that the past can, and should, be seen as a key to the future. What happened in the past is likely to happen again – unless conditions change. This is significant in the context of global climate change and environmental destruction.
Our planet Earth has witnessed a number of ‘mass extinction events’: a large number of plant and animal species all over the world become extinct over a relatively short period of time. The most dramatic mass extinction was the Permo-Triassic one about 251 million years ago, when 95% of all marine species became extinct. The causes then were entirely natural because humans did not exist yet.
Extensive volcanism in Siberia released vast quantities of greenhouse gases into the atmosphere. This caused rising global temperatures over a period of several million years, and with it, changing ocean chemistry and circulation.
Not all life was wiped out; a very small number of survivor species made it through the tough times and went on to recover, diversify and evolve in a process that took millions of years. Other mass extinctions and climate changes occurred eventually, leading to life as we know it today.
In view of the environmental challenges the world faces today, one wonders if we are heading on a similar catastrophic path – this time caused by our own actions. Are we on a path that is irreversible? Are we heading towards the next biodiversity crisis? Can we adapt to the changes fast enough? Can we ‘fix’ the damage already done?
The Intergovernmental Panel on Climate Change has proven that science is clear on the issues we face. Climate change could kill more than a third of the world’s biological diversity, both plant and animal.
Extreme weather events have changed in frequency and/or intensity over the last 50 years, including the incidence of extremely high sea levels. Evidence from all continents and most oceans indicate that many natural systems are being affected by regional climate changes, especially rising temperatures.
As a consequence, weather patterns are changing, with an increase in droughts, floods and severe storms. In turn, this is affecting hydrological systems and water supplies.
Human activities have led to an overall increase in greenhouse gas (GHG) emissions of 70% between 1970 and 2004; the largest growth in GHG emissions being from energy supply, transport and industry, and a lower rate of growth (but still growing!) from residential and commercial buildings, forestry and agriculture. The Panel found that it is very likely that these GHG concentrations are causing the increase in global average temperatures.
To sum it all up, anthropogenic activities are causing climate and environmental change. Geologists can compare what is happening now with what happened in the past. Some state that a new geological epoch, the Anthropocene, has started (Zalasiewicz et al. 2008). It is marked by an increase in erosion, rising carbon dioxide levels, rising temperatures and accelerated extinctions on land and in the seas.
World climates have changed, and very dramatically, at other key moments in the geological past. Planet Earth has gone through several ‘greenhouse’ and ‘icehouse’ states, and fossils in rocks show us that ‘life’ has survived. Using the past as an indicator for the future, we can expect some forms of ‘life’ to survive the damage humans are currently inflicting on Earth.
However, can we react fast enough to preserve a world in which we humans ourselves can survive, and more importantly, a world worth living in?
The world is today at a cusp. World leaders met at the Rio+20 Summit to discuss the fate of the planet. GHG emissions are still increasing. Biodiversity is still plummeting. If things do not change, the trend will continue. The geological record is a good place to look into to find evidence of the consequences.
Human beings have never lived in harmony with nature – they just caused fewer disturbances in earlier times because of smaller populations and less developed technology (Hallam, 2005). The geological record of fossil life shows that humanity has so far played the role of planetary killer, concerned only with its own short-term survival (E.O. Wilson 2002).
Humans brought about the extinction of large land animals way back in the Pleistocene (over a million years ago) and the trend has continued ever since. Biologists estimate that, if we continue ‘business as usual’, half of all animal and plant species will be gone by the end of the century. Furthermore, the global population is currently around 7 billion and is sharply rising.
Ban Ki Moon, Secretary-General of the United Nations, recently stated that time is not on our side. Are the Earth’s past climate ‘greenhouse’ states and mass extinctions to be an indicator of our fate in the future? It is certainly worth pondering.
Dr. Dominique Dodge-Wan is a senior lecturer in the Department of Applied Geology, School of Engineering and Science, Curtin Sarawak. She teaches sedimentary geology related units and geological mapping. Her professional experience includes groundwater resource studies in a number of countries and on different rock types. Her research interests centre on limestone, karsts and groundwater flow. She can be contacted at +60 85 443 939 or by e-mail to firstname.lastname@example.org.