As I visited the website of National Oceanic and Atmospheric Administration (NOAA) to check the latest daily average of carbon dioxide emissions in the atmosphere, I was startled to see that as of August 12, 2018, the level of carbon stood at 407.31 parts per million (PPM).

Another alarm was sounded in a research in the Proceedings of National Academy of Sciences of the United States of America (PNAS) on how surging temperatures can push the earth system towards its limits, if breached, could prevent the stabilisation of the climate and cause continued warming on a ‘Hothouse Earth’ trajectory even if emissions are reduced. The research titled Trajectories of the Earth System in the Anthropocene warned that if the planetary threshold is crossed, it would lead to higher temperatures never witnessed in the past 1.2 million years and sea levels never experienced before, indicating that it could even lead to the extinction of life on earth.

The current temperature of the earth is at over 1°C above pre-industrial levels and in the future, the earth system could potentially follow many pathways depending on the amount of greenhouse gas emissions (GHGs) in the atmosphere. The research paper encircles 2°C temperature as the planet’s ‘Thin Red Line’ as the danger of 2°C warming could activate important tipping elements, which could raise the temperature further to activate some other tipping elements in a domino-like cascade and increasing the earth temperatures unprecedentedly.

The scenario of increasing temperatures activating tipping elements implies that even if the Paris climate agreement’s target of 1.5°C to 2.0°C rise in temperature is met, the looming threat of a cascade of extreme weather events is ‘highly likely’ that could push the civilization irreversibly onto a Hothouse Earth pathway.

The research further revealed that some feedback processes are dependent on the rate of climate change. If the rate of climate change is small, the carbon emissions will rise gradually along with subsequent warming of the climate, however if the rate of climate change is fast, the thin red line can be crossed which can lead to major shifts in the ecosystem in the shape of extreme weather events such as wildfires, insect attacks, erratic rainfall patterns and droughts etc.

Tipping cascades

The research shows tipping elements that fall into three clusters based on their estimated threshold temperature. Cascades could be formed when a rise in global temperature reaches the level of the lower-temperature cluster, activating tipping elements, such as loss of the Greenland ice sheet or Arctic sea ice. These tipping elements, along with some of the non-tipping element feedbacks (e.g., gradual weakening of land and ocean carbon sinks), could push the global average temperature even higher, inducing tipping in mid- and higher-temperature clusters. For example, loss of the Greenland ice sheet could trigger a critical transition in the Atlantic Meridional Ocean Circulation (AMOC), which could altogether, by causing sea-level rise and southern ocean heat accumulation, increase ice loss from the East Antarctic ice sheet.

If a planetary threshold is crossed leading toward the Hothouse Earth trajectory, getting back to the course of stabilised trajectory would become very difficult no matter what actions human societies might take at that time. Hothouse Earth is likely to be uncontrollable and dangerous.

Although the research is authoritative in nature, Adil Najam, the inaugural dean of Frederick S. Pardee School of Global Studies, Boston University, clarified that the Hothouse Earth hypothesis posts a scenario rather than a prediction. He said, "Though the research paints a scary scenario, its key purpose is to galvanize climate action within major emitter countries by painting a picture of what the worst case scenarios might look like."

Hothouse impacts

A hothouse trajectory will substantially decrease agricultural production, flood coastal areas, increase coastal storms and eliminate coral reefs by the end of this century or earlier.

Tahir Rasheed, Chief Executive Officer of South Punjab Forest Company (SPFC) and a senior environmentalist, warned that in Pakistan hothouse earth will lead to massive forest fires, extreme drought, abrupt rainfall patterns, increasing flash floods and Glacial Lake Outburst Floods (GLOFs) and heatwaves in urban centres.

In an exclusive conversation with TNS Erik Solheim, Executive Director, United Nations Environment Programme (UNEP), warned that climate change entails more frequent and intense extreme weather events, and global warming is already playing out right in front of our eyes. "What we’re seeing now, however, is just a taster of what is likely to happen."

What to do next?

The research proposes to create a pathway where humans fundamentally change their role in the planet that can lead to a stabilised course. Stabilised earth is shown with a temperature rise no greater than 2°C above pre-industrial levels and would require deep cuts in greenhouse gas emissions (GHGs), increasing carbon sinks, removing CO₂ from the atmosphere, solar radiation management and adaptation to global warming.

Erik Solheim showed optimism when asked if climate change could be addressed. "Fortunately, we know what the solutions are. We need to get off our carbon addiction and make the shift to clean, renewable energy. Recent years have shown that this shift can be cheap and easy. We have to explore every avenue for energy efficiency - that means applying strict standards on vehicles, buildings and appliances. And if we make our economies more circular and shift to a reuse and recycle model that generates significantly less waste, that efficiency will also help us," added the UNEP head.

How can Pakistan prevent itself from Hothouse impacts?

Will Steffen, one of the main authors of this research and chair of Antarctic Science Advisory Committee, and associated with Australian National University (ANU), when contacted how the Hothouse Earth can affect the South Asian region, he categorically said that, "The large continental glaciers of the Himalayan range are likely to be eliminated in a Hothouse Earth phenomenon."

"Not only that but the South Asian summer monsoon system is vulnerable to fundamental shifts in behaviour at a 3-5°C temperature rise above pre-industrial levels," warned Steffen.

Regarding how the Hothouse Earth will exacerbate sea level rise in South Asia, Will Steffen informed that the region can witness rising seas of at least 10 metres and probably more. "This would have very significant impacts on the coastal regions of South Asia, including some very large coastal cities in the region."

Dr Adil Najam, on the other hand, said that in the light of this research, Pakistan should stay focused on the much more immediate climate crises that will pave way to a possible hothouse. He said, "Pakistan’s climate challenges are immediate and related to adaptation. Heatwaves, floods, glacial melt, droughts and sea-level rise are now in Pakistan’s near-term horizon and our focus must remain on this."

He went on to say, "While the scary metaphor of a hothouse is grabbing global headlines, I hope that those in Pakistan will remain focused on our real and immediate climate challenges. Importantly, Pakistan must not lose its own focus from adaptation, nor should we let that focus be distracted at the global level."

"Pakistan should stand up and make its voice heard on the global stage, because it is among the nations that will be hardest hit from climate change. From the fragile mountain ecosystems of Hunza and Nagar to the plains of Sindh and Balochistan, there is hardly anyone that will be untouched. Pakistan needs global action to reverse emissions and to help adapt to a changing climate," said Erik Solheim.

Tahir Rasheed expressed concern that the deadly phenomenon can make the achievement of Sustainable Development Goals (SDGs) further difficult. He said, "Humans as a society should collectively address this menace. Population control, emission reductions, geoengineering and climate smart agricultural practices are few areas that need attention to prevent the world from embarking upon the hothouse pathway.

The research ends with a final warning that even if the stabilised earth pathway is achieved, humanity will face a turbulent road of rapid changes and uncertainties that will challenge the resilience of human societies. The Hothouse Earth signals the end of civilisation and serves as a clarion call to every developed and under-developed country to adopt the sustainable course and most importantly join hands to implement the Paris climate agreement in letter and spirit, if mankind is to survive.