Currently, the Earth System is on a Hothouse Earth pathway driven by human emissions of greenhouse gases and biosphere degradation toward a planetary threshold at ∼2 °C (Image Credit: PNAS)
The entire world is currently discussing this much important
latest scientific paper published in the PNAS about the risk of Earth entering
into what the scientists call “Hothouse Earth” conditions. The paper, with lead authorship of Will
Steffen (and many co-authors) from the Stockholm Resilience Centre of the
Stockholm University. The paper, that
needs to gravely worry us all, basically tells that “Even if the carbon
emission reductions called for in the Paris Agreement are met, there is a risk
of Earth entering what the scientists call “Hothouse Earth” conditions.”
A “Hothouse Earth” climate will in the long term stabilize
at a global average of 4-5°C higher than pre-industrial temperatures with sea
level 10-60 m higher than today, says this study, suggesting, “maximizing the
chances of avoiding a “Hothouse Earth” requires not only reduction of carbon
dioxide and other greenhouse gas emissions but also enhancement and/or creation
of new biological carbon stores.”
Currently, global average temperatures are just over 1°C
above pre-industrial and rising at 0.17°C per decade and the Paris Agreement asks
to limit it between 1.5°C to 2.0°C. According to the lead author, "Human
emissions of greenhouse gas are not the sole determinant of temperature on
Earth. Our study suggests that human-induced global warming of 2°C may trigger
other Earth system processes, often called “feedbacks” that can drive further
warming - even if we stop emitting greenhouse gases."
Ten natural feedback processes have been considered by the
authors. These are: permafrost thaw,
loss of methane hydrates from the ocean floor, weakening land and ocean carbon
sinks, increasing bacterial respiration in the oceans, Amazon rainforest dieback,
boreal forest dieback, reduction of northern hemisphere snow cover, loss of
Arctic summer sea ice, and reduction of Antarctic sea ice and polar ice sheets. Some of these are “tipping elements” that
lead to abrupt change if a critical threshold is crossed. These feedbacks could
turn from being a “friend” that stores carbon to a “foe” that emits it uncontrollably
in a warmer world, warns the study.
The study confirms that cutting greenhouse gases are not
enough. “Maximizing the chances of
avoiding a “Hothouse Earth” requires not only reduction of carbon dioxide and
other greenhouse gas emissions but also enhancement and/or creation of new
biological carbon stores, for example, through improved forest, agricultural
and soil management; biodiversity conservation; and technologies that remove
carbon dioxide from the atmosphere and store it underground,” says the
paper.
(The above note is prepared from the story about this study that appeared in www.stockholmresilience.org)
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Our Note: As has been rightly emphasised by the paper,
humans need to redefine their relationship with Earth and Ecosystems. We need to chart new pathways of living in
harmony with nature and drastically rethink the way our economic growth models
are working at the moment. If necessary,
we need to slow down on such growth and promote forest and natural resources
conservation measures through complete involvement of local people and
indigenous communities, promote green communities and infrastructure in our
ever growing urban spaces, and many more efforts that can help us from saving from the ensuing disastrous scenarios. Paris Agreement is as
such not enough to save us from the “Hothouse Earth”, we need more actions than
promised there.
Ranjan Panda
Convenor, Combat Climate Change Network, India
Email: ranjanpanda@gmail.com
Skype: ranjan.climatecrusader
Tweet @ranjanpanda
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