What happens post 1.5?

Martina Mifsud, Malta – 23 years old

According to the Climate Action Tracker (CAT) Warming Projections Global Update- December 2018, as presented by Prof. Richard Betts, Professor of Climate Impacts, University of Exeter & Met Office Hadley Centre, if we continue exercising our current policies and practices, we are on a steady trajectory heading towards a global temperature increase of between 2.5 ˚C and 4.4 ˚C by 2100. Climate-related risks for the earth’s inhabitants are higher with a 1.5 ˚C temperature increase when compared to the present situation, but carry lower risks when compared to the potential 2˚C increase. Such risks are dependent on the magnitude and rate of warming, the geographic location, the development and vulnerability situations of the considered area, and ability of adaptation. This begs the question, if the risks are high already with a 1.5 ˚C increase, what effects would a 3.5 ˚C (mean) increase have?

Wet Bulb Globe Temperature

This measures the amount of temperature, humidity, wind speed, and the effect of visible and infrared radiation on humans. With an increase in temperature, climate change has the potential to induce excess sweating. This can been as acceptable by some, but we must not forget to take into consideration that with increasing humidity, the effectiveness of sweat release is reduced, hence directly increasing the heat stress on humans.

With a 3 ˚C increase, we will also start seeing extremes such as forest fires happening in areas previously deemed safe, such as Spain, Portugal and Greece.

However, there is no way to predict which way the earth will go. We can experience droughts and precipitation deficits, as, according to the IPCC report, these are predicted to be higher at 2 °C compared to 1.5 °C of global warming in some regions. But we can also experience intensified precipitation, which risks are determined with medium confidence to be higher with a 2 ˚C.

Future Sea Level Rise

If emissions are limited to maintain an increase lower than 2 ˚C, global sea level rises are kept below 0.5m by the year 2100, as according to the IPCC-AR5 projections. Whilst this would be maintaining a positive attitude, the negative counterpart would effect a 1m global sea level rise by the same year. If at any point, the Antarctic marine ice sheet and/or the Greenland ice sheet are irreversibly lost, sea level is predicted to have a multi-meter increase over hundreds to thousands of years. This sea level rise increases the exposure of coastal areas, especially those which are low lying, and also increases the vulnerability of small islands. The risks involved affect many human and ecological systems- including higher saltwater intrusion and flooding, damaging of infrastructure. The rate of sea level rise is confirmed to be relatively slow at 1.5 ˚C when compared to 2 ˚C. This would allow a longer period of adaptation[1], with time given to learn how to best manage, litigate and mitigate on how to properly approach the climate changes.

The predicted amount of people affected by cyclones reimagined with higher sea levels affect more and more people. The Sidr cyclone in Bangladesh, 2007, affected 1.9 million people, but if the sea levels had been 0.5m higher than they were, as would be the case in a few years, more than double the amount of people would have been affected- roughly 4.1 million. With the highly possible 1m increase back in 2007, seven million people would have been affected. And with a 1.5m sea level increase, a staggering 9.1 million people. So it’s not ‘just a hundred centimetres which will have a negligible effect’- it’s real people’s lives and needed food and lands which will be affected all over the world- irreversibly.

Effects on Biodiversity and Ecosystems, and human-related risks

Species loss and extinction will be presented, although the risks related to these two effects are determined to be lower with a 1.5 ˚C increase compared to a 2 ˚C. If limited to 1.5 ˚C, impacts on terrestrial, freshwater and coastal ecosystems will be less drastic, and hence, such resources can serve better to their full extent. Not surpassing the same temperature increase will eventually reduce increases in ocean acidity, and fight the decrease of ocean oxygen levels. The security offered when limiting to 1.5 ˚C extends to marine biodiversity, fisheries and ecosystems.

Availability of food and water, and comfort of living conditions through factors such as security, economic growth, and so on, are projected to decrease with a global warming of 1.5 ˚C, and further diminish with a 2 ˚C increase.

These are some of the reasons why the nine quantitative planetary boundaries were proposed- which dictate the boundaries which humankind can continue to thrive within, using the earth’s resources to a safe extent. The challenges of the 21st century are described by Prof. Johan Rockström (Environmental Sciences) as two; the abuse, misuse and overuse of natural global resources, and the challenge to ensure public investment and expenditure- the people have to want it enough to act on it. Because “everybody is interested, but nobody is really taking care of it”.  The nine planetary boundaries should keep us on track, limiting the extents of our actions. The boundaries comprise of:

  • Biosphere integrity
    • Biodiversity will be reduced, species lost and extinction of the masses
    • Changes in ecosystems because of human activities have been very rapid in these last fifty years
  • Land-system change
    • Land converted to human use- needs to be controlled, give value for people, not for money, as in the end, people would need that same land for trees and crops.
    • Reductions in biodiverse species
    • Effects on water flows- cleanliness, availability and accessibility
    • Effects on the cycles of carbon, nitrogen and phosphorous in our environment and atmosphere
  • Freshwater use
    • Amended, for better or worse, hydrological systems. Effects can be reversible or irreversible
    • By 2050, approximately half a billion people are estimated to be suffering from water stress across the globe
  • Biochemical flows
    • Cycles of carbon, nitrogen and phosphorous have been changes because of detrimental human actions
    • Such cycles therefore accordingly alter the need for fertiliser use in growing crops
    • Human activities at the present moment convert the most nitrogen into reactive forms when comparing to all other Earth’s terrestrial processes combined.
  • Ocean acidification
    • Approximately a quarter of all carbon dioxide emissions as result of human activities is eventually dissolved in the oceans, therefore being converted to carbonic acid. This alters the ocean chemistry and the pH of the surface water
    • This same carbon dioxide reduces the amount of carbonate ions available in the water, which crustaceans need for their skeletons and shells
  • Atmospheric aerosol loading
    • Aerosols affect clouds through the interaction with the water vapour within, therefore potentially affecting the quality and quantity of precipitation
    • Affect the amount of solar radiation absorbed or reflected back into the atmosphere- therefore having a direct effect on climate and its change
    • Air pollution, aerosols being one of the pollutants, kills approximately 800 thousand people every year
  • Stratospheric ozone depletion
    • With the decrease in ozone thickness, comes the increase in incidence of skin cancer, and increase to damage to terrestrial and marine biological systems
  • Novel entities
    • Together with chemical pollution, these can have possibly irreversible effects on living organisms and their physical environment
  • Climate change
    • One effect amongst others is the loss of polar sea ice- something which is for sure irreversible and will have a very negative effect all around the world

As long as we live within these boundaries and not exploit any resources; as long as we do not cross the line, our planet will continue to provide an adequate and satisfactory living space for all its inhabitants. We need to use these resources wisely, as there is enough for everybody.  But everybody needs to be in on the fight for climate action, and it should be taken fast. If we wait until 2020 to start our fight against climate change, it may be impossible to hold global warming below 1.5 ˚C[2]. It already is a huge challenge now, and when sharing his opinion, Prof Hans Joachim Schellnhuber, the outgoing director of the Potsdam Institute for Climate Impacts, says that “we will miss the target, that’s very sure. The question is, by what margin?”

But we need to keep a positive albeit assertive attitude to the challenge. We can work for it, and we can make it happen. We can destroy the planet, at least for humanity, but in ten years we can completely change it. The decision is up to us.

[1] Interestingly, adaptation needs for global warming are lower for a 1.5 ˚C than for a 2 ˚C increase.


IPCC REPORT- IPCC, 2018: Summary for Policymakers. In: Global warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [V. Masson-Delmotte, P. Zhai, H. O. Pörtner, D. Roberts, J. Skea, P. R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J. B. R. Matthews, Y. Chen, X. Zhou, M. I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, T. Waterfield (eds.)]. World Meteorological Organization, Geneva, Switzerland, 32 pp.

Climate Action Tracker- Warming Projections Global Update, December 2018

Will Steffen, Johan Rockström, Robert Costanza, How Defining Planetary Boundaries Can Transform Our Approach to Growth, The Solutions Journal, Volume 2, Issue 3, May 2011, Pages 59-65

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