In a new study published in the Proceedings for the National Academy of Sciences, climatologist Will Steffen from Australian National University warns that earth is on the cusp of entering a “hothouse” state—a point where runaway effects of climate change will continue to cumulate even after halting the emissions of greenhouse gasses. Crossing this threshold could result in higher global average temperatures and sea levels higher than those at any time in the Holocene era.
Environmentalists have long cautioned against the dangers of runaway effects of climate change. Small changes in the composition of the Earth’s atmosphere or oceans can have cascading large-scale effects. Like a giant set of dominos, one perturbation in the massively complex system that is the Earths climate can have far-reaching consequences.
The new study, co-authored by 15 other researchers from institutions around the world, warns that we are past the point where Earth will naturally cool on its own. Instead, we are now faced with the opposite problem. The accumulation of greenhouse gasses and the disturbing of natural systems such as ocean currents create positive feedback mechanisms that accelerate the rate of warming. The authors call this a “Hothouse” state.
In particular, the study states that the general trend of rising temperatures has disrupted numerous “Gaia” feedback loops; mechanisms that stabilize the Earth’s climate and make it conducive for human habitation. Permafrost thawing, forest and grassland death, and the upturning of soil are all processes by which carbon is released into the atmosphere and these processes are only accelerated by the general trend of warming. An accelerated rate of forest and plant death means fewer organisms to draw carbon from the atmosphere. Consequently, this could mean an exponential rate of carbon increase as more natural mechanisms to draw carbon out of the atmosphere are disturbed by human activity.
In the paper, Steffen and his co-authors outline 10 of the greatest potential feedbacks which could ultimately cascade into large-scale changes in climate. Poised as the most dangerous and immediate threats are the slow thawing of permafrost in arctic tundras, the production of methane by deep-sea ocean vents, and the loss of arctic ice sheets. Research indicates that by 2020, we could see an up to 60% reduction in the total area of permafrost of the earth. Permafrost acts naturally as a sink for atmospheric carbon, so the rapid loss of permafrost is detrimental on two fronts; (1) melting permafrost releases large amounts of atmospheric carbon and (2) the reduction of permafrost means less natural mechanisms to act as carbon sinks. Rising acidity levels of the world’s oceans can stimulate the release of methane in deep ocean vents.
Melting ice sheets contribute to rising sea levels. Considering that over 80% of the human population lives within 60 miles of the coast, rising sea levels could bring about the displacement of millions of people as homes are flooded and farming lands are destroyed. Melting ice also deposits freshwater into the world’s ocean, which can disrupt its finely defined currents. Ocean currents serve as conduits for weather patterns so a change in ocean currents can lead to unexpected changes in weather.
In general, the paper highlights what it calls “tipping points”, points where the behavior of an ecosystem will non-linearly and abruptly change behavior. Crossing these tipping points manifests in large-scale famines, droughts, flooding, and other bouts of extreme and unpredictable weather. Crucially, these process cannot be stopped once they start. They will form a positive feedback chain where each perturbation can resonate into big changes. The paper predicts that our current rate of greenhouse gas emissions could see a full degree increase in the average global temperature.
If anything, the new study puts focus on just how interconnected all the various ecosystems in the world are and how seemingly unrelated features of the environment are connected. The paper cites cutting down trees in the rain forests as something that can have unexpected effects. In addition to damaging wildlife habitat, cutting down rainforests increases the risk of dry season fires. Rainforests transpire large amounts of water and stimulate precipitation, less rainforest means less rain and so less protection against dry season fires.
With respect to current efforts to combat climate change, Steffen and the other researchers note in a public statement that current efforts by nations are “unlikely to help us avoid this very risky situation, where many parts of the planet could become uninhabitable for humans.” Steffen acknowledges that in order to effectively combat climate change, there must be a cultural shift in values; a change in lifestyle away from mass consumerism and exorbitant waste production. Studies show that the average American has a carbon footprint almost double the size of the global per capita average. Recent movements have sought to understand how to adapt this narrative of renewable energy into a sound ethos for policy decisions.
Public Views On Climate Change
Despite the repeatedly verified universal agreement in the scientific community regarding the existence of human-caused climate change, a Pew Research Poll from 2008 indicated that approximately 50% of Americans do not think that anthropogenic global warming is occurring. Notably, Americans were more likely than individuals from any other nation to disagree that anthropogenic climate change exists. There are a number of reasons for the disparity between scientists’ perception and public opinion of climate change. Climate change is an inherently complex topic so it can be difficult to understand. Non-scientists generally have different ways of assessing evidence than scientists, so it is harder for non-scientists to see patterns in data. Lastly, the vast majority of this non-convergence of opinions between scientists and the public is due to concerted efforts by well-funded institutions in the United States to recast the debate on climate change as a policy issue. These institutions have succeeded in establishing a frame that is completely at odds with scientific consensus and evidence.
There is room for optimism though, There is evidence that engaging in informal dialogue regarding climate change can help peoples’ understanding on the issue and researchers are working on methods to inoculate the public against misinformation about climate change.