Simply put, climate is the "average weather” defined over a certain time-period.
It represents the average state of variables such as temperature, precipitation and wind; their patterns and possible extremes, over a period of time.
The World Meteorological Organization (WMO) defines 30 years as the classical period for climate expression.
In a more wider sense, the climate system is the expression of the cumulative state of the five following sub-elements :
- atmosphere
- hydrosphere
- cryosphere
- land surface
- biosphere
Our planet’s climate has been constantly changing for a long time now ! Much before even humans came into the picture. In other words, it has been in a state of forever change.
In the last 800,000 years, it has experienced 8 cycles of chill-ice-ages-periods and warmer-periods.
The end of the last ice age was about 11,700 years ago, which also marked the beginning of the modern climate era in which the human civilisation has come to thrive.
This evolving nature is driven by various natural factors that shape our climate system. This includes,
- the solar radiation our planet receives from the sun,
- the amount of aerosol/particles in our planet's atmosphere,
- the ability to reflect heat off the surface of our planet &
- the concentration of greenhouse gases in our planet's atmosphere.
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It is important to note that each of these factors interact with each other and our planet’s climate system in their own unique ways.
While,
higher solar radiation received from the sun and atmospheric greenhouse gas concentration increases global average temperature;
higher reflectivity of its surface and atmospheric aerosol quantity decreases global average temperature.
All these moving factors cumulatively influence the average global surface temperature of our planet over a given time; and in doing so determine our planet's climate state.
It is their gradual fluctuation over a course of time, that it leads to natural cycles of climate change.
What has triggered the current state of climate change
Among the many factors affecting climate, the severe climate change we are witnessing today is primarily due to the extraordinarily high concentration of greenhouse gases in our atmosphere.
For context, It is important to note that the greenhouse gas concentration in our atmosphere has remained relatively stable for centuries until the last 250 years.
But this is no more the case.
In fact, in 2019 the atmospheric carbon dioxide concentration (a greenhouse gas) was higher than at any time in at least the last 2 million years !!
And concentrations of methane and nitrous oxide (other greenhouse gases) were higher than at any time in at least 800,000 years !!This extremely high level of greenhouse gases concentration has in-turn increased the ‘solar heat’ trapping ability of our atmosphere.'.
This has increased the average global surface temperature and in turn has triggered a series of planetary-level climate system change events such as those in precipitation patterns, extreme weather events, ice cover and sea levels – that define the climate crisis today.
The exponentially soaring global temperature in the recent decades on account of higher greenhouse gas concentrations, has been accompanied by a widespread rapid changes in other aspects of our climate system viz. atmosphere, ocean, cryosphere & biosphere as well.
Reducing Ice/Snow Cover
As our planet is warming up & our climate changing, there is (1) shrinking of Greenland and Antarctic ice sheets, (2) declining Arctic Sea Ice & (3) retreating glaciers (including those in the Himalayas).
For context, between 1993 and 2019 Greenland lost an average of 279 billion tons of ice, while Antarctica has lost about 148 billion tons !!
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Rising Sea Level
As we lose our ice cover to our water bodies (see above), the global sea level is rising. It has not only risen by about 20 cm between 1901 and 2018 but the speed at which the sea level is rising - is also increasing.
Consider this, the sea level rose by the same amount in the last two decades as it did in all last century. In fact, it's risen faster since 1900 than over any preceding centuries, in at least the last 3000 years.
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Oceans
The oceans naturally absorb heat & carbon dioxide (a greenhouse gas) from the atmosphere it comes in contact with. As atmospheric greenhouse gases concentration has increased along with global warming over the last decades – our oceans have also begun to absorb more heat and carbon dioxide from the atmosphere.
The oceans today are warmer with the top 100m of having warmed up by as much as 0.33°C since 1969.
Also, the continuous absorption of carbon dioxide emissions by our oceans have turned them acidic.
They have absorbed a quarter (20%-30%) of total anthropogenic carbon dioxide emissions, which has in-turn increased their surface waters acidity by about 30%, since the beginning of the Industrial Revolution.
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Extreme Weather Events
With the drastic collapsing of the climate system in recent decades, there has been an increase in frequency of extreme weather events.
The precipitation patterns have changed, the hurricanes, droughts and heatwaves have become more intense than ever before in modern human history.
This is particularly a problem when you realise that our agriculture as well as modern infrastructure ( incl cities ) are designed with a stable predictable climate in mind - whose very existence is not threatened.
What makes today's climate change event, a global threat?
While we are aware that our planet’s climate system has changed over large periods of time ( remember, the 8-cycles of chill-ice-ages-periods and warmer-periods in the last 800,000 years, for context) – it has never changed the way it is changing now.
The current period of climate change that we are living through is the first of its kind.
What makes it so different from our planet’s historic climate change periods is
the 'speed of change' & the 'reason behind it'.
Consider this:
Speed of Change:
The speed at which our planet is warming up (and the climate system changing) is unlike anything our planet has experienced in many recent millennia.
In fact, it has been changing so fast that it has left very little time for adaptation - both from a biological evolutionary standpoint (even including humans); and our everyday world order.
Not only is our flora and fauna unable to keep up pace with our changing climate; so is our state of agricultural practices, human settlements, and infrastructure – that has evolved to current states over several centuries.
Reason of Change:
Unlike past episodes of climate change which occured gradually, under natural circumstances, it is for the first time that our climate system is changing because of “human interference”.
Beginning with the mid-18th century industrialization, the human society became heavily reliant on energy—primarily from the burning of fossil fuels—to power modern life, from electricity production to large-scale manufacturing.
While fossil fuels have driven much of this progress, their combustion releases vast amounts of greenhouse gases into the atmosphere, a fact overlooked for much of history.
It is this continuous release of greenhouse gases since industrialization that has largely triggered global warming and then the severe climate change we are experiencing today.
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It is this speed of change and the unchecked human-interference - that has rendered the current state climate change into a global threat - that needs active work to avoid and manage.
It is important to note here that despite all that we know, we continue to release greenhouse gases into our atmosphere now (in fact more than ever before) - with little clarity on the solution pathway.
Future projections on the extent of climate change
To put it straight, we are no longer in a position to stop the on-going climate change that we have set off in the last few centuries.
Global warming (and sea level rise along with all other climate change manifestations) will continue for centuries, even if greenhouse gas concentrations were to be stabilized today. That is because of the the sustained global warming potential of greenhouse gases over many years.
It is in this context, that the extent/higher-cap of the 'likely warming extreme' has become important.
How high our global temperatures will rise and climate change manifestations will play out will depend on how well we do in controlling our global greenhouse gases emissions & find ways to draw back those we have release into our atmosphere the last few centuries.
The IPCC, which forms the foremost authority on climate science on climate change timely releases the most likely estimates. They make this scientific prediction based on several future socio-economic scenarios of our planet & the human society's social fabric.
We now know that by 2100 (end of this century), the temperatures of our planet will increase by 2.7°C relative to 1850–1900 - if we do nothing and stay at our current level of annual emissions until 2050.
The absurdity of this lies in the fact that the last time global surface temperature was sustained at or above 2.5°C higher than 1850–1900 was over 3 million years ago !!
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While all future likely socio-economic pathway that the human society is likely to follow, will result in the continuation of global warming, it has been projected to vary between the following extremes:
- 1.4°C, if we take care to hit net-zero emissions around mid-century (Year 2050)
- 4.4°C, if we completely ignore climate change and instead go on to roughly double our carbon dioxide emissions,
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Clearly, we are in full control of our planet’s future.
Our collective behavior in the next few decades will decide if we are able to delay a full-scale climate change, slow it down or even contain it with minimum damage.
We have come a long way since 1972’s First World Climate Conference – where governments were warned for the first time, to be mindful of activities that could lead to climate change and to evaluate the likelihood and magnitude of climatic effects.
Fast forward to today, the direction of the climate action movement today is led by a legally binding international treaty called the Paris Agreement.
It was adopted by 196 Parties at the UN Climate Change Conference (COP21) in Paris on 12 December 2015 and entered into force on 4 November 2016.
(UNFCCC is a convention focused on stabilizing atmospheric concentrations of "greenhouse gases" at a level that would prevent dangerous anthropogenic interference with the climate system)
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The Paris Agreement aims to strengthen the global response to the threat of climate change by:
(a) limiting the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C,
(b) increasing the ability to adapt to the adverse impacts of climate change and foster climate resilience and low greenhouse gas emissions development,
(c) making finance flows to support the above in order to limit the global average temperature it expect all participants (i) to peak global greenhouse gas emissions as soon as possible, and (ii) to undertake rapid reductions thereafter to net-zero emissions in the second half of this century.
All participants are expected to develop a nationally ‘climate action’ plan every five year, besides a pathway of how it will achieve a long-term low greenhouse gas emission development in the long run.
This has effectively lead to the surge in Net-Zero pledges across the world that we now see.
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While the Paris Agreement is not the first international effort to contain climate change; it is quite indispensable today.
It is not far-fetched to say that the success of the climate action movement today hinges on the success of the Paris Agreement. If we fail, we may not have the time to re-invent a whole new way of international climate action cooperation.
With each year we would lose to re-inventing the climate negotiations, we will risk higher emissions and that much closer to the worst-case climate scenario.
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